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HYDROGEOCHEMICAL STUDIES AND THEIR ENVIRONMENTAL SIGNIFICANCE
UPON DAL LAKE
DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS
FOR THE AWARD OF THE DEGREE OF
iViuittv of $t)iloiB(oplip IN
BY
GUbZAR AHMAD MUKHTAR
Und*r Xhm Supervision of
Prof. Sajjad Husain Israili
DEPARTiy/IENT OF GEOLOGY ALIGARH MUSLIM UNIVERSITY
ALIGARH, (U. P.)
1990
*7*r /',
^ ^^^UviJ^Vi'''^'^'
DS2062
I R 5 - 1 A VIEW OF DAL LAKE ( J t K )
NAGIN LAK
^ SRIftJAiAR
,. jiii^a.
'% %^\ I -
LOATING / G-ARDEN
IRS-1A LISS II FCC MAY 24,1988
Ti
With best compdments from : iSRO/DOS
Dedicated To My
Parents
Dr. Sajjad Husain Israili M.Sc, Ph.D., D.Sc
I.A.S. (Netherland). L.A.G.C (Praha) PROFESSOR a CHAIRMAN
DEPARTMENT OF GEOLOGY ALIGARH MUSLIM UNIVERSITY ALIGARH—202 002 (INDIA) Phone . (0571 ) 25 G 1 D Telex : 564-230-AMiJ-liJ
Pol.No.:
Dated .
CERTIFICATE
This is to certify that the dissertat ion entit led
HYDROGEOCHEMICAL STUDIES AND THEIR ENVIRONMENTAL SIGNIFICANCE
UPON DAL LAKE i s an o r i g i n a l con t r ibu t ion of MR. GULZAR AHMAD
MUKHTAR in t h e f ie ld of Environmenta l Geology which was c a r r i e d
out unde r my s u p e r v i s i o n . I t h a s not been p u b l i s h e d in p a r t s or
full a n y w h e r e e l s e .
MR. MUKHTAR i s a l lowed to submi t t h i s work for the award
of M . P h i l , deg ree of Al iga rh Muslim U n i v e r s i t y , A l i g a r h .
( P/ S u p e r v i s o r
Residence: 2/43, LAXMI BAI ROAD. NEAR MARRIS ROAD CROSSING, ALIGARHZioJOoT
ACKNOWLEDGEMENTS
I take this opportunity to express my deep sense of
gratitude to my reverved teacher Professor SaJJad Husain
Israili* Supervisor and Chairman, Department of Geology,
Aligarh Muslim University, Aligarh. His erudite supervision,
guidance and high scholarship has immensely contributed
towards the formulation of this dissertation. His human
approach has even been more inspiring and encouraging.
Without his active cooperation the success of this programme
was impossible.
words fail to extend my deep sense of gratitude to
Mr. Noman Ghani, Reader, who has provided useful suggestions
and guidance; and Mr. Feroz Javed, senior Technical Assistant,
Geochemical Laboratory, Department of Geology, Aligarh Muslim
University, Aligarh, who has rendered assistance in analysing
major lot of the samples. I am thankful to Director, Instru
mentation Centre, University of Kashmir (J & K) Government,
Srinagar, and Sclentist-Incharge, Soil and Water Testing
Laboratory, Department of Agriculture (J & K) Government,
srinagar for their excellent facilities and all help made
available to roe during the analytical stage of this study.
Thanks are due to Mr. Sallmuddin Ahmad (Cartographer)
for his excellent cartographic work, and Mr. Zakir Husain
for providing library facilities during the completion of
this study. I am thankful to Mr. S.M. Hasan for his Impaceable
typing.
Mr, NUrul Hasan and Mr, Arif, K.A., Senior Research
Scholars of the Department of Geology, deserve my thanks
unreservedly for manuscript reading and mutual discussions.
I express my gratitude to the authorities of the Jammu
and Kashmir Government for their library facilities and for
providing the various primary and secondary data and maps
used in the compilation of this disseirtation. Dr. M.A. Kawosa
(Director); chief Engineer; Mr. Bashir Ahmad Qadri (Deputy
Director); and J,S. Bali (Geologist Engineering) of the
Departments of Ecology, Environment and Remote Sensing;
Urban Environment Engineering; Soil Conservation and Power
Development respectively deserve special mention.
Lastly, to all my friends and colleagues, and to whom
soever it is due, I extend my thanks for cooperating with me
in several capacities directly and indirectly in the conduct
of this study. Mr. M.F. Loan, Mr. A.R. Shah and Mr. M.R. Bhat
deserve special mention,
ALLAH ALONE IS BESOUGHT FOR HELP AND ON HIM WE ALL DEPE^D.
( Gulzar Ahmad Mukhtar )
CONTE Mrs
Page No,
LIST OF TABLES
LIST OF FIGURES
i
iii
CHAPTER-I INTRODUCTION
Location of the Study Area
Statement of the Problem
Aim, Objectives and Significance of the Present work
Review of the Earlier Work
1
4
5
CHAPTER-II METHODS AND TECHNIQUES
Field Methods
Laboratory Methods
13
13
16
CHAPTER-III MORPHOMETRY AND ENVIRONMENTAL HAZARDS OF THE DAL LAKE CATCHMENT
Morphometry
T e r r a i n
C l i m a t e
Hydrology
Dra inage
Environmenta l Hazards
Sedimentation
Urban Impact
Waste Disposal
Floral Growth and Development of Floating Gardens
21
22
28
41
43
43
50
50
53
55
55
-ii-
CHAPTER-IV LANDUSE OF THE DAL LAKE CATCHMENT
Existing Landuse
Suggested Landuse
Page No.
60
60
70
CHAPTER-V GEOLOGY OF THE DAL LAKE CATCHMENT
Palaeozoics
Mesozoics
Cenozoics
weathering Characteristics
74
78
83
85
88
CHAPTER-VI HYDROGEOCHEMISTRY OF THE DAL LAKE ... 95
Water Chemistry ... 95
Physico-chemical Characteristics... 108 of Water
Major Metals ... 109
Trace Metals ... 113
Water Quality Criteria in ... 120 relation to its Use.
Environmental Significance of ... 122 major and Trace Metals in Lake Waters
Sediment Chemistry ... 136
Physico-chemical Characteristics... 140 of sediments
Major Metals ... 144
Trace Metals ... 146
Environmental Significance of ... 154 major and Trace Metals in Lake Sediments
Probable Source and Derivation of ... 159 Metals in rhe Lake Environment
CHAPTER-VII CONCLUSIONS & RECOMMENDATIONS ... 175
REFERENCES 189
- 1 -
LIST OF TABLES
Ptige No.
Table-1
Table-II
Table-III
Table-IV
Table-V
Table-VI
Table-VII
Table-VIII
Table-IX
Table-X
Table-XI
Table-XII
Table-XIII
Table-XIV
Table-XV
Table-XVI
Morphometrical Data of t h e Dal Lake. 26
Area Estimation of Mi crow a t e r sheds of 34 the Dal Lake Catchment,
Sub-Catchments of Dal Lake Catchmoat, 32
Average Slope of the Subcatchments of 40 Dal Lake.
Relationship of Slope Categories with 42 other Physical Factors of t he Lake Catchment.
Dal Lake Drainage Basin Cha rac t e r i s t i c s . 47
Sectorwise Population aroiind Dal Lake, 54
Area Estimation of the Landcover Feature 62
around t h e Dal Lake,
Landuse Figures of Dal Lake Catchment, 65
Geological Succession of the Catchment. 76 Areal and Percentagewise Dis t r ibu t ion of 77
Li thouni ts in t h e Lake Catchment, Tentative Geochemical Background Levels 89 of Metals in Li thouni ts of T e r r e s t r i a l Environment,
Water Sample Locations and Sample Numbers 99
in Dal Lake Basin,
Water Sample S ta t ions in Dal Lake Sub-basins, 101
Metal concentration in Dal Lake Waters, 102 Average Metal Concentration in Waters of 104 Dal Lake Sub-basins,
- ± 1 -
Page No.
Table-XVII Metal C o n c e n t r a t i o n s i n Waters a t four 105 S t a t i o n s o£ Lake Sub -bas in s .
Table-XVIII Physico-Ghemical and B a c t e r i o l o g i c a l 106 C h a r a c t e r i s t i c s of t h e Dal Lake Waters,
Table-XIX Sediment Sample Loca t ions and Sample 138
Numbers i n Dal Lake Basin.
Table-XX Metal Concen t ra t ion i n Lake Sediments . 141
Table-XXl Average Metal Concent ra t ion i n Sediments 142 of Dal Lake S u b - b a s i n s .
- i i i -
LIST OF FIGURES
Pacje No.
E i g u r e - 1
F i g u r e - 2
F i g u r e - 3
F i g u r e - 4
F i g u r e - 5
F i g u r e - 6
F i g u r e - 7
F i g u r e - 8
E i g u r e - 9
F i g u r e - 1 0
E i g u r e - 1 1
F i g u r e - 1 2
F i g u r e - 1 3
F i g u r e - 1 4
F i g u r e - 1 5
L o c a t i o n Map of Dal Lake Ca tchment , 2 Jammu and Kashmir ( I n d i a ) ,
View o f Dal Lake from Su la iman H i l l o c k . 3
Map showing D a l Lake S u b - b a s i n s , 24
Map showing Morphome t r i c P a r a m e t e r s o f 27 Dal Lake .
C o d i f i c a t i o n Map of Da l Lake Catchment 33 (lEZ) .
Map showing D a l Lake S u b - C a t c h m e n t s . 36
Map showing g e n e r a l i z e d S l o p e C a t e g o r i e s 39
o f Dal Lake C a t c n m a i t .
D r a i n a g e P a t t e r n s o f Dal Lake Ca tchment . 46
Map showing Dugwel l , T u b e w e l l , i :acploratory 49 B o r e h o l e and S p r i n g L o c a t i o n s a round Dal Lake . Dal Lake Catchment H a z a r d s i n d i c a t i n g 51 l i i v i r o n m e n t a l D e g r a d a t i o n upon Lake Water Body.
S c h e m a t i c P l a n s showing E v o l u t i o n of Dail 59 Lake .
Landuse Map o f Dal Lake and i t s i m m e d i a t e 51 a i v i r o n s .
Landuse and Landcove r Map of Dal Lake 64
C a t d i m e n t .
G e o l o g i c a l Map of Dal Lake Ca t chmen t . 75
Map showing Water Sample L o c a t i o n s i n 97 D a l Lake B a s i n .
- i v -
Page No.
I l gu re -16 Map showing Water Sample S t a t i o n s i n 98 Lake S u b - b a s i n s .
Elgure-17 Average Concent ra t ion of Ca* Mg, Na and 123 K i n Waters of Dal Lake.
Elgure-18 Average Concent ra t ion of Pb, Mi, a i , Co, 123 Sr and Cu i n Waters of Dal Lake,
Figure-19 Average Concen t ra t ion of Ba, Cr, Rb and 124 Cd a t four S t a t i o n s of Dal Lake Sub-bas ins (During Summer Season) .
Figure-20 Average Concen t ra t ion of 00^, HCO,/ CI 124 and SO. a t four S t a t i o n s o r Dal Lake Sub-bas ins (During Summer Season ) .
i l g u r e - 2 1 D i s t r i b u t i o n of Ca, Mg, Na and K in Waters 129 of Dal Lake.
Figure-22 D i s t r i b u t i o n of Sr, Pb, Co and a i in 130 Waters of Dal Lake.
Figure-23 Var ia t ion i n Average Concen t ra t ion of 133 Calcium and Magnesium in Waters of Dal Lake S u b - b a s i n s .
Figure-24 Var ia t ion in Average Concen t ra t ion of 133 Sodium and Potassium in Waters of Dal Lake S u b - b a s i n s .
F lgure-25 Var ia t ion i n Average Concen t ra t ion of 133 Sr, Pb, Co, Zn, CU and lln i n Waters of Dal Lake Sub-bas ins .
Figure-26 Var ia t ion i n Rb, Cd, Cr and Ba a t four 135 S t a t i o n s of Dal Lake Sub^bas ins (During Summer Season) ,
Figure-27 Var ia t ion in CO,, HCO-, CI and SO a t 135 four S t s t i o n s o t Dal Lake Sub-bas ins (During Summer Seascn) .
Figure-28 Map showing Sediment Sample Loca t ions 137 in Dal Lake Basing
- V -
Page No.
Figure-29
I lgure-30
I l g u r e - 3 1
i l g u r e - 3 2
Figure-3 3
Figure-34
Figure-35
Figure-36
Figure-37
Figure-38
Figure-39
Figure-40
Average Concen t ra t ion of Ca, Fe, Mg, Na and K i n Dal Lake Sediments .
Average Concen t ra t ion of Sr# Mn, Zn cind Cr i n Dal Lake Sediments.
Average Concent ra t ion of Cu, Rb, Ni, Pb, Ba and Co i n Dal Lake Sediments .
Average Concent ra t ion of Cd and Li in Dal Lake Sediments .
D i s t r i b u t i o n o f Ca Mg, Na and K in Sediments of Dal Lake.
D i s t r i b u t i o n of Sr, Pb, Co and a i in Sediments of Dal Lake.
D i s t r i b u t i o n of Cu, Mi, Fe and Ni in Sediments of Dal Lake.
D i s t r i b u t i o n of Rb, Cr, H and Ba in Sediments of Dal Lake.
Var ia t ion in Average Concen t ra t ion of Ca, Mg, Na, K and Fe i n Sediments of Dal Lake S u b - b a s i n s .
Var i a t ion i n Average Concen t ra t ion of Sr, TUf Ka and Cr i n Sediments of Dal Lake S u b - b a s i n s .
Var ia t ion i n Average Concen t ra t ion of Pb, Co, Cu, Ni, Rb and Ba i n Sediments of Dal Lake Sub-bas in s .
Var ia t ion i n Average Concen t ra t ion of Cd and Li i n Sediments of Dal Lake Sub-basin s.
155
155
156
156
162
163
164
165
169
170
170
171
CHAPTER - I
INTRODUCTION
LOCATION OF THE STUDY AREA :
The Dal Lake body is located on the Pleistocene alluvium
in the Kashmir Himalayas. It is a high altitude (alt. 1580
meters approximately a.m.s.l.), fresh water drainage lake and
has a urban to suburban status. Geographically* the Dal Lake
(Lat. 34°05« - 34* 09• N,Long. 74°50* - 74°53' E) lies to the
northeast of the city of Srinagar (Kashmir, India) . It is a
lake body of Dachigam drainage basin. The lake catchment falls
within the latitudinal and longitudinal extent of 34* 04* -
34*^14' N and 74°49« - 75°09' E respectively (Fig. 1 ).
The lake is used both as a source of food and water.
It sustains agriculture and supplies water for drinking
purposes. Dal Lake being a tourist spot is a place for
recreational/ swimming and boating activities. The lake body
has an ideal physiographic location (Fig, 2 ). The aesthe
tics of the lake body adds beauty to the gardens and tourist
infrastructure within and around the Dal Lake. It also serves
as a flood basin (reservoir) at the time of spate and excess
of flood waters are discharged into the river Jhelum via a
gated structure 'Dal Gate* to save the lake body from inundation,
—r-;— 7 5°E
DAL LAKE AND ITS CATCHMENT ]
3«_
SRINA6AR
TSONT KHUL
JAMMU& KASHMIR
S R . N A G A R . ^ ^ ! ^ ^ CATCHMENT
JAMMO^ t, OJSOjOOKm
FIG. 1 LOCATION MAP OF DAL LAKE CATCHMENT JAMMU AND KASHMIR ( INDIA )
2}
ho
m
o
a >
>
m
o
to
>
>
O o
STATEMENT OF THE PROBLEM t
The Dal Lake is a vestige of major post-glacial lake.
The lake has been gradually yet continually reduced in size
by drainage, reclamation and natural sedimentation.
Besides, natural drainage and absence of proper sewerage
system prevailing in the catchment all discharge their efflu-t
ents into the lake thereby deteriorating its quality of water.
Domestic, urban, effluents from tourist based infrastructure
and agricultural (agricultural fields and orchard^) return
flows all contribute to the water quality deterioration.
These discharges have also resulted in the prolific weed
growth upon the lake bed and occur in the floating state
as well.
Increase in agricultural activity and the reduction of
plant cover on the hillsides surrounding the lake with the
consequential increase in surface erosion and deposition in
the lake basin and leaching of soil nutrients have added
increasing quantities of nutrient-rich run-off.
The gradual reclamation of the lake to provide building
and vegetable growing land and the increase in the area of
the floating gardens have combined with natural processes
to reduce the area of open water within the lake basin.
Human settlement on the lake, the reclaimed land within
the lake basin and around the peripheries of the lake has
also added nutrient rich seepage and effluents. More recently,
the direct discharge of sewage from tourist based infra
structure has added human waste to the point where health
hazards are serious. Furthermore, the lake weed, the interrup
tions to the flow of the lake water and the reduction in the
volume and surface area of the lake have reduced the capacity
of the lake to respond to the stresses placed on it. Poor
water quality and pockets of stagnant water are all too
apparent.
These environmental hazards have resulted in the nitrate
and phosphate pollution besides damaging the quality of the
lake waters. Hence the health and very life of the lake is
threatened.
AIM, OBJECTIVE & SIGNIFICANCE OF THE PRESENT WORK S
The aim and objective of the present study is to evaluate
the morphometry, establish landuse pattern and geology of the
catchment, to determine the water and sediment chemistry of
the lake body. This work is first of its kind which deals
with the physical features, geology and landuse of the whole
of the catchment, of which the Dal Lake constitutes a water
body. The determination of these parameters will help to
evaluate the environmental impact upon the lake body in
particular and lake catchment in general. The impact,
pollutional level and environmental significance of each
major, trace and plant nutrients upon the lake ecosystem
can be evaluated from the pre-determined hydrogeochemistry
of the lake body, which would in turn establish the quality
of lake waters and its hydrogeochemical regime. The geo-
chemical data will also help to establish the geochemical
background levels as no metal based industry exists in the
catchment.
The study is also significant in nature because it would
serve the base for all future water quality studies Including
the monitoring of the lake waters. Again the significance of
the present study will be to suggest the geo-environmental
measures that would save the lake from future deterioration
and to suggest the remedial measures of short term and long
term nature for the all time preservation of this geomorphic
feature which attaches considerable economic importance from
geoengineering, economic and aesthetic point of view.
REVIEW OF THE EARLIER WORK J
The Dal Lake and its catchment has been studied from
time to time for different aspects. Certain attempts have
been made regarding fresh water bodies of the Kashmir of which
Dal Lake constituted a part of these studies. During the last
two or three decades the lake body has mostly been studied
from biological point of view.
Ganju and Srivastava (1961) made a detailed petro-
graphic study of the agglomeratic slates of the lake catchment
in the neighbourhood of Srinagar near Bren (Nishat). The study
was aimed to throw light on the nature and origin of this
interesting and conspicuous formation.
Das and Subla (1963) have studied the Kashmir lakes as
faunal habitates, dealing with 'the Ichthyofauna of Kashmir*
their history, topography, origin, ecology and general
distribution.
Zutshi (19 68) worked on the ecology of some Kashmir
lakes whereas Zutshi and Koul (1968) made a Joint study on
the ecological problems associated with Kashmir lakes. Kant
and Kachroo (1971) worked on the phytoplankton population
dynamics and distribution in two adjoining lakes of Srinagar
viz., the Dal Lake and the Nagin Lake, Zutshi et al. (1972)
made limnological studies of high altitude Kashmir lakes.
Kant and Kachroo (1977) made limnological studies of
Kashmir lakes, wherein hydrological features, composition
and periodicity of phytoplankton in Dal and Nagin lakes were
dealt with. The authors made a detailed account of the macro-
flora, ecological variable, diurnal movements, distribution
8
and seasonal dynamics of phytoplankton in two adjoining lakes,
the Dal and the Nagin la'kes situated in Srinagar, Kashmir.
Zutshi and Khan (1978) worked on lake typology of
Kashmir. They classified the Kashmir lakes using multiple-
criteria approach. A system of classification based on multiple-
criteria approach has been introduced for Kashmir lakes. The
lakes are categorized into s (1) Valley, (2) Forest and (3)
Mountain types. The valley lakes are further separated into
(a) drainage (b) semi-drainage and (c) non-drainage sub-types.
The lake typology is correlated with various limnological
features. The classification would facilitate future limno
logical studies of the region.
Zutshi and Vass (1978) made an attempt on the
•Limnological studies on Dal Lake - chemical features".
The work pertained to the chemical characteristics of lake
waters. The various parameters studied are pH, dissolved
oxygen, conductivity, alkalinity, calcium, magnesium, sodium,
potassium, orthophosphate, especially with regard to their
seasonal fluctuations in three basins, viz., Nagin, Gagribal
(Lokut Dal) and Hazratbal. The work was aimed to monitor its
present trophic level in order to form a base line for future
conservation programme,
Enex consortium (1978) of New Zealand prepared a report
on the pollution of Dal Lake, Srinagar, Kashmir. The work is
a compilation of physical* chemical and biological features
wherein recommendations and plans have been proposed to
conserve the lake from future deterioration.
Agarwal (1981) made studies on water and surficial
sediments of Dal Lake. The mineralogical composition, physical,
chemical and engineering characteristics of the surficial
sediments was also investigated. Parameters, such as pH,
phosphates and silicates of waters and sediments of Dal Lake
have been carried out. Engineering characteristics included
determination of /^tterberg's limits, permeability, trlaxial,
unconfined compression test and one dimensional consolidation
tests. The distribution and compositional chatacteristics of
the lake surficial sediments have been evaluated.
Zutshi and Vass (1982) made an attempt on the limnolo-
gical studies on Dal Lake, wherein biological features were
dealt within detail. Data have been obtained on distribution,
production and dynamics of macrophytic vegetation, qualitative
and quantitative aspects of plankton population, colonization
of benthic fauna and the nature of fish population. The results
were used to evaluate the present trophic status of the lake
to develop baseline for future ecological surveillance.
Bhat (1982) studied the Karewa Lake in Kashmir valley,
its extent, genesis and modification. The object of the study
was to re-assess more comprehensively the extent of the Karewa
10
Lake that formed the sedimentary basin for the Hirpur
formation as well as the factors that may have contributed
to its origin, and to describe in relative detail the modi
fication that the lake underwent, in stages, in its areal
spread through the quaternary period, on the basis of the
field observation now gathered. Since the Dal Lake is
thought to be a vestige of great Karewian lake, hence it
threw some light on the origin of the Dal Lake basin as well.
Srivastava (1982) made an attempt on the siltation of
Dal Lake. The work revealed the geological considerations
responsible for the siltation in the Lake body. Hence certain
causes were unfolded and certain remedies were proposed to
save the lake body from future deterioration.
Ahmed (1982) studied the phosphorus dynamics in
Hazratbal basin of Dal Lake. It was intended to determine
the distribution and balance of this essential nutrient
(ortho-phosphate) in Hazratbal basin of the Dal Lake, Also
Kango and Zutshl (1986) made an attempt to study the dynamics
of phosphorus distribution in a shallow lake and presented
data on dynamics of three forms of phosphorus i.e. ortho-
phosphate (PO.-p), particulate phosphorus (PP) and total
phosphorus (TP) in Hazratbal basin of Dal Lake, Srinagar.
Pallaria and Kawosa (1987) mapped the Dal Lake and
Wular Lakes using aerial photographs and landsat frames for
their water quality. The objective of the study was to carry
11
out the qualitative and quantitative mapping of the water
pollutants like suspended sediments, algae, aquatic weeds,
etc. identification of pollution zones; and to develop a
methodology for the monitoring of water quality parameters.
Zutshi (1987) has presented the impact of human
activities on the evolution of Dal Lake environment. The
author made an attempt to record the ecological history of
the lake and its eutrophic gradient as a result of varied
anthropogenic perturbations.
Kango et al. (1987) studied the humic material in
Himalayan Lake sediments; interaction of lake humic acids
with certain heavy metals - Ca, Zn, Fe and Mn using their
isotopes; evaluated the stability constants of humic acids
with copper and zinc. Kango and Dubey (1987) worked on the
sediment chemistry of Kashmir Himalayan Lakes. The authors
determined the clay mineralogy viz., illite, calcite and
chlorite using XRD and DTA methods. The ionic activity
product (IAP) and equilibrium constant (K ) of calcium and
carbonate ions for the ambient lake waters was used to trace
the origin of calcite.
Koul and Zutshi (1987) studied pollution in Kashmir
lakes and determined average chemical composition of some
lake waters of Kashmir. The parameters included major and
some trace elements of the lake waters.
12
The environmental chemistry of zinc in Himalayan lake
sediments was investigated by Kango (1987). An attempt was
made to describe various aspects of environmental chemistry
of zinc in the sediment samples collected from six Himalayan
lakes having different morphometric features.
Environmental geochemistry of iron and manganese in
six Himalayan lakes was studied by Kango et al. (1987),
wherein the abundance and distribution of iron and manganese,
the two important mobile metals, in an aquatic environment have
been presented. Data on the selective extraction of Fe and Mn
and their accumulation in humus material was also reported.
Shah et al. (1988) worked on the metallic elements in
surface sediments of Dal Lake, Srinagar, The elements investi
gated include Ca^ Fe, Cu, Zn, Rb, Sr, Zr, Sn, Sb, Ba and
organic carbon. Each sample was then exposed to the radiation
source of an X-ray fluorescence spectrophotometer. The concen
tration of all metals except zirconium show a positive correla
tion with organic carbon In Dal Lake, Srinagar. Zirconium shows
an anomalous behaviour. The metal concentrations being very
low are strongly influenced by the channel characteristics
and time of the year and may be taken as geochemlcal background
levels as there is no metal based industrial activity in the
catchment area. The offshore zone surface sediments have a
higher organic carbon content and, therefore, a greater
accumulation of metals.
13
CHAPTER - II
METHODS AND TECHNIQUES
For every research study a set of methods and techniques
are required for accomplishing the plan formulated for the
successful completion of the work on the said topic or broad
theme, A research study without preconceived methodology to
attain the desired targets and to work on the sub-topics of
the main topic usually remains unacconplished. Keeping in view
the requirement to attain the desired results, the present
study has been broadly fulfilled by conducting the field and
laboratory work. Hence this chapter covers the field and
laboratory work or methods undertaken necessarily required for
completion of the task.
FIELD METHODS s
In the very first instance a base map was prepared
demarcating the Dal Lake catchment. This was done with the
help of available Survey of India Grand toposheets on
1 t 50,000 scale. Extensive and intensive field work was
carried out to prepare various relevant maps of the entire
catchment and individual maps of the Dal Lake body.
14
The maps prepared on the base map include location plan
and generalized slope categories map of the catchment with the
help of Wentworth (1930) method which involved quite an elabo
rate procedure. A square grid is superimposed on a contour map
of the area under study, and all contour crossings are tabula
ted. The procedure is repeated with an oblique grid being
spread over the same area. The results obtained from the two
exercises are then averaged and the slope characteristics are
estimated with the help of the formula i
Average number of contour crossings x contour interval
3361
(where denominator 3361 is a constant value in the formula).
A map showing morphometric parameters prepared with the
help of the procedure followed in the manual of Hakanson (1981)
Maximum length (L„_„) is determined by a line connecting the
two most remote points on the shorelines; Maximum Effective
Length (L^) is determined by a line connecting the two most
distant points on the shoreline over which wind and waves way
act without interruptions from land or islands; Maximum Width
^^max^ is determined by a straight line drawn perpendicular
to the maximum length connecting two most remote extremities
on the shoreline without crossing land; and Maximum Effective
15
Width (B ) is a straight line drawn perpendicular to maximum
effective length connecting the two most distant points on the
shoreline. Thus maximum effective width may not cross land or
islands. Mean width (B in km.) is determined by the formula -area
B = a/L (where 'a* is lake/in sq. km. and 'L * is maximum ' max i- max
length in km,). Maximum depth (D ) in mts. is the greatest rno3v
known depth of the lake. Relative depth ('D * in per cent)
is determined by the formula -
D - °max . / T T r " 20 JT"^
(where 'D • is the maximum known depth in meters and 'a* is max
area the lake^in sq. km.). Direction of major axis is the bearing
of maximum length of the Lake body.
Further, the geological and landuse data collected in
the field has been transferred on the base map of the catchment.
Geological map has been prepared with the help of extensive
reconnaissance geological studies conducted in the field
enabling to demarcate various lithounits and the succession
was established with the younger-older relationship criteria.
With regard to the landuse map the data of the toposheets has
been superimposed on the base map followed by thorough field
checks demarcating lands under various category uses. All
areal figures on lake catchment, landuse, lithounits have
been determined with the checkered transparent paper technique
16
(CTP technique) which usually involves a checkered transparent
graph paper. Besides, the maps indicating water and sediment
locations in the lake body and around its iimediate vicinity
has been prepared.
LABORATORY METHODS t
Water, sediments and rocks are the materials analysed
from diverse point of view. Physico-chemical analysis, bacte
riological and biological analyses of the water is made to
assess the pollution status of a river or lake body. Water
bodies are investigated for their hydrogeochemical regime
and are monitored for the environmental pollution as well
with the help of various methods. Even various parameters
are determined for the groundwater quality studies which
find an application in the drinking, irrigation and indus
trial water supplies. Besides the water as a medium for the
environmental analysis, the sediments are also investigated
from the pollution point of view. The chemical analysis of
the rocks and other geological materials are vital.
For establishing a hydrogeochemical regime of the Dal
Lake water body the materials investigated include water and
sediment samples. Water samples were collected at various
sampling stations together with surficial sediments at the
17
corresponding lake bottom. The material were collected to
determine the major (cations and anions) are trace metal
concentrations in the samples. These concentrations were
interpreted for the environmental analysis of the lake body.
The water samples for chemical analysis were collected
in well cleaned and treated 500 ml. capacity douDle stoppered
plastic bottles. The bottles after collection of samples were
capped with innerlid and then capped and sealed with wax on
the spot.
Another group of samples was simultaneously collected
from the same location in 500 ml. capacity plastic bottles
for trace metal studies. These samples were treated at site
with 10 ml. 1 s 1 HNO3 and then capped and sealed with wax.
Both the category of samples were transferred to
laboratory. The former group of samples was utilized for the
major metal studies and the later for trace metal studies.
For analysing the eight sanples collected at the four sampling
stations of the sub-basins of Dal Lake, similar procedure of
collection and preservation was followed.
The samples were later on filtered to remove the
suspended matter which could otherwise clog the capillary
of the instrument. The calibration curves of each metal were
prepared by using the various standard solutions of the known
concentrations of the metal, the absorbance values were read
therefrom and concentrations expressed in ppm.
18
The samples for metal studies were analysed by methods
recommended in standard text (Trivedy et al., 1984). Fifty
samples of water were analysed for major metals (only cations)
and trace metals, whereas eight representative samples were
analysed for major metals (both cations and anions) and trace
metals as well. Ca, Mg and trace metals in 50 samples were
determined at the Instrumentation Centre, University of Kashmir,
Srinagar (Jammu & Kashmir), Na and K in these 50 samples was
determined at the soil and water testing laboratory, Departnrent
of Agriculture, j & K Government, Srinagar. Major (both cations
and anions) and trace metals in the four representative water
samples were determined in the Geochemical Laboratory,
Department of Geology, Aligarh Muslim University, Aligarh. In
all such quantitative metal deductions, the Flame Photometer
(Elico-model) and Atomic Absorption Spectrophotometer (902 -
Double Beam) were used besides usual volumetric techniques.
In case of chloride determination, a 50 ml of water samples
was taken, the reagents used for this anion determination are
AgNOj and K2CrO^ on the titration apparatus. The results thus
obtained are expressed in ppm. Sulphates were determined by
the gravimetric method and the results are expressed in ppm.
In this case 100 ml of the water is taken from the sample
collected and the reagents utilized are NaCl, HCl, ethyl,
glycerol, BaCl2 and Na2S0^. The bicrabonate determination
19
has been done with the help of titration method wherein the
HC1# methyl orange and phenolpthalein indicators, sodium
carbonate are the reagents utilized. The results of this were
expressed in ppm.
The sediments of the bottom of the lake body were collec
ted from the same stations as for the water samples. One
thousand grams of sediment of the bottom were collected in
polythene bags and were properly sealed. These were transferred
to the laboratory for the metal detejrminatlon. The pH of the
sediment samples was determined on Digital pH meter usually
available in laboratories for routine analysis. The samples
were then oven dried and fine powdered. For major (Ca/ Mg, Na
and K) and trace metal determination, a fine powder of sediment
weighing 1 gm was taken. The same fine powdered quantity was
digested. Triple-acid digestion was performed upon the samples
which included nitric acid (HNO^), hydrofluoric acid (HF) and
perchloric acid (HCIO-). One gram of sample was digested in
teflon beakers on the hot plate. The fine digested residue
is mixed with 100 ml of distilled water and transferred to the
bottles for the metal detexrminatlon. A stock series of known
concentrations of each metal was prepared and the instrument
was standardized with the series. The values obtained in
absorbance were then read from the calibration curves prepared
from the stock series. Hence the concentration values obtained
20
are calculated and expressed in ppm. In case of sediments
both the major and other trace metals were determined by
the Atomic Absorption Spectroscopic technique.
21
CHAPTER - III
MORPHOMETRY AND ENVIRONMENTAL HAZARDS OF THE DAL LAKE CATCHMENT
The form of a lake basin and the shape of the lake will
depend partly on the forces that produced the basin and partly
on the events that occur in the lake and in its drainage basin
after it has been formed. This chapter does not discuss the
events that have produced the lake basin together with the
lake body, however, throws light upon physical features of
the lake body and area surrounding it. The chapter, therefore,
includes the morphometrical aspects of the lake and deals with
terrain, climate, surface water hydrology and drainage charac
teristics of the lake and its catchment. Further, paragraphs
on the environmental hazards facing the Dal Lake, prevailing
in the catchment have been added.
The significance of dealing morphometry and environ
mental hazards is that the morphometry provides the present
physical status of the lake body while as the environmental
hazards gives us an idea about the changes brought to the
lake morphometry and the damage bringing to the lake body
in particular and the catchment in general.
22
M0RPH0r4ETRY :
The Dal Lake constitutes a water body (loop in outline)
of the Dachigatn Drainage Basin (Fig. 1 ). The Lake has a
Catchment area of about 381,44 sq. km. The chief river feeding
the Lake is the Telbal Nallah (called upstream Dachigam Nallah)
which enters the Lake towards its north side (Fig. 2 ). A
drainage network also feeds the Lake from other shore-sides,
apart from certain springs emanating from the Lake bed. The
two outflows of the Dal Lake are Dal Gate and Nallah Amir Khan.
Therefore, the lake is connected with Tsont - Khul at the
southwest corner with the Gate popularly known as 'Dal Gate•;
and is connected to the Nagin Lake at the Ashai bagh with a
bridge known as Nagin bridge, the water of which eventually
flows into the Anchar Lake via a canal called Nallah Amir Khan.
The other inter-connection of the Dal Lake with the Nagin Lake
is at the Sadia Kadal called Sadia Kadal bridge and is also
connected to a Mar called 'Babadem* with the help of canal
passing underneath the Nawpora bridge. The Babadem (which is
an isolated water body or pond) and Anchar Lake fall outside
of this Lake Catchment.
Besides Dal Lake, the other water bodies of the Catchment
are the Marsar (glacial/snowfed Lake) and the Nagin Lake. Harwan
23
reservoir is artificially created mini water body situated
near Harwan and is meant for domestic water supplies. Marsar
lie in the extreme east and Nagin to the west of the Dal Lake
Catchment. The Dachigam Nallah originates from Marsar and the
Nallah has a flow length of 39 kms (approximately).
In addition to the natural drainage entering the Dal
Lake, various domestic, commercial establishment effluents
and urban sewerages are being discharged into the Lake basin
untreated through various drains or directly by population
clusters settled around the lake periphery or within the lake
body. The lake also serves as a flood compensating basin
(reservoir), the sluice gate at the Dal Gate functions as
spillway at the time of the spate.
Broadly, the Dal Lake is further divided into several
distinct parts (Fig. 3 ) s (1) Hazratbal Basin, (2) Bod Dal,
(3) Lokut Dal, and (4) Floating Garden Area. The north of the
lake is known as the Hazratbal Basin, the largest sheet of
water in the middle of which lies the island called Sona Lank.
The Bod Dal or large lake, on the east side contains the
little island of chinars called Rupa Lank or Char Chinari.
Lokut Dal (or Gagribal basin) the first and smallest division
lies to the southeast, is separated from the Bod Dal by a
narrow tongue of land. The west of the Bod Dal is Floating
Garden area which is the cluster of the landstrips separated
24
FIG. 3 MAP SHOWING DAL LAKE SUBBASINS
25
by narrow waterways. The Boulevard area which is a linear
strip of lake extending from Dal Gate up to Nehru park and
bounded between Boulevard road and Floating Garden area* is
in general treated as part of Lokut Dal.
The lake is crossed by a narrow path running along a
raised causeway called the Suttu or Sut-i-Chodri, This cause
way starts from near the end of the Naidyar bridge in
Kraliyar, and crosses the lake.in a northeasterly direction
terminating on the south side of the village of Isheberi,
close to the north end of the Nishat Bagh. It is about three
and a half miles long, and its average width is 3.65 meters;
there are nine bridges along its course. The average depth
of the lake is not more than 2.13 to 3.04 meters, though in
one place it reaches 7.92 meters. It extends from five to
six miles from north to south, and two to three miles from
east to west, forming its broadest point (Gazetteer of
Kashmir and Ladakh, 1974),
The morphemetrical data evaluated for the Dal Lake
is indicated in Table- I and Figure- 4 . The water depths,
however, reported for the Dal Lake sub-basins are j Maximum
water depth for Hazratbal Basin, Bod Dal, Lokut Dal and
Floating Garden Area are 3.5, 2,6, 2.6 and 2.0 meters
respectively, it is reported that the average o.f maximum
water depths is 2.54 meters whereas the average of minimum
26
Tab le - I t MORPHOMETRICAL DATA OF THE DAL LAKE,
1 . Maximum w a t e r D e p t h . (D ) . m t 3 . = 3 . 5 max
2 . Average o f Maximum w a t e r D e p t h ' s , m t s . . = 2 ,54 ,
3 . Average of Minimum w a t e r D e p t h ' s , m t a . = 1 .82\
4 . T o t a l Lake Area (A) , Km^ = 18 .43
5 . Maximum L e n g t h (L ) , Km, = 7 .75 in Q Js»
6 . Maximum E f f e c t i v e L a i g t h ( L ^ ) , Km. = 6 .00 7 . Maximum Width (B ) , Km. = 4 ,00
max
8. Maximum Effective Width (B^), Km. = 3.5
9. Mean WLdth (B), Km. = 2.37
1 0 . R e l a t i v e Depth (D^.), % = 0 . 0 2
1 1 , D i r e c t i o n of Major Axis = SW - NE
S o u r c e : P a r a m e t e r s from 5 t o 11 d e t e n r d n e d a s p ^ r p r o c e d u r e
adop t ed by L a r s Hakanson, A Manual of Lake
Morphometry, s p r i n g e r - V e r l a g , 1 9 8 1 .
27
7^ 50
H
Nag'in Lak
KOH-I-MARAN
1750
R a i n a w a r i o I
SRINAGAR
34 '
5'
otamar
h b e r i
i s h Q i b a g h
O N i s h Q t
B a g h H u s o i n
o D Q n p u r
L o r n
o o B r e n M o n s q a m
K a r a p u r Q
a z i Bogh
r a h b o g h
M t s . 5 0 0 0 5 0 0 Mts . \ \ -J
FIG. A MAP SHOWING MORPHOMETRIC PARAMETERS OF DAL LAKE
28
water depths Is 1^82 meters (Enex, 1978). Hence, it is
observed that the lake bottom represents a heterogeneous
topography.
Terrain :
The Dal Lake Catchment is fan shaped and broadens west
ward. The western watershed limit is by and large a flatter
area except for 4,5 kms. length along which the average eleva
tion is 2000 meters. The weatershed limits rise high towards
the north and east of the Catchment, The average elevation
along the northern, eastern and southern watershed is 3706
meters, 4200 meters and 3000 meters respectively. On the whole
the Dal Lake Catchment represents varied topographic fenturos
which have been affected by the various geomorphic processes
(glacial, alluvial «nd fluvioqlncial).
The general relief of the Catchment is a basin which
comprises the Dal Lake situated at an altitude of 1580 meters
approximately and a steep escarpment at an elevation of 4390
meters located along northern watershed limit between Bat Gul
(3858 meters) and HanQalmarg (4275 meters). Most of the
terrain of the Catchment with moderate and steep rises, in
general represent a precipitious topography. Out of the total
Catchment area very little portion is represented by flatter
29
and terraced topography, particularly exhibited by the south
western portion.
The southwestern portion of the Catchment possess mostly
low relief or is almost flatter terrain which accommodate the
Dal and the Nagin Lakes of this Catchment. The topography In
the immediate east and the north oi the Dni Lak« waterbody
is flatter and terraced. The west and southeast of Dal Lake is
a flat terrain, whereas its northern portion attains gradual
rise and the terraced topography which terminates above 1693
meters (approximately) gives rise to new topographic barrier
(a part of the northern watershed limit) comprising of steep
undulating ridges (NE-SW trend). A steep ridge having mostly
NW-SE trend start from Harwan reservoir and terminates at the
extreme south of the Dal Lake. This mountainous range whlcli
is an offshoot of the Zabarwan range has an arcuate form and
conform to the eastern and southern foreshores of the Lake,
thus, a long linear piedmont terrace is formed between this
arcuate mountain range and the eastern and southeastern for*»-
shores of the Dal Lake. The above mentioned ranges (trending
NE-SW and NW-SE) intersect roughly at the Ilarwan thus forming
a knot pattern structure. The southwestern portion of the
Catchment also contains two prominent mountain hillocks
(Sulalman hllock 1855 meters, and Kohl-Maran 1750 meters).
A spur is located in the immediate east of the Dal Lake near
30
Krai Sangri. This spur is geologically famous as the Bren
Spur (1694 meters).
The Koh-i-Maran occupies the most dominent position on
the northern outskirts of srinagar city. This hillock ll^n
between the Dal and Anchar Lake, and rises about 76 meters
above the surrounding area. The Sulaiman hillock which is a
rocky eminence eixsts at the south of Dal Lake, it forms the
end of a spur from the Zebarwan mountain, and is separated
from the mountain range by a very deep gully. It is evident
ttiat the Sulaiman hillock and the Kohi-Maran are only the
continuation of the west-north west spur of Zebarwan, and
appear as detached hillocks on account of the thickness of
the lacustrine deposit (Gazetter of Kashmir and Ladakh, 1974).
These hillock embrace the shores of the Dal Lake.
The east of the Catchment (area north and south of the
Dachigam nallah) and far north of the Dal Lake as mentioned
earlier is characterized by precipititious terrain. The
prominent locations in the eastern portion are Marsar (3800
meters), Gugiyar (3602 meters), Mahadeo (3979 meters), Mamnyat
(2535 meters), Barabal (2614 meters); and in the far north
portion is Takia Sangrish (2200 meters).
The terrain to the north and south of the Dachigam
nallah is complex. It flows mostly in the V-shaped valley
which starts narrowing from the Harwan reservoir up to the
31
nnllah jjourcf I.e., Marsar. Thin [inrt of th^ Cntchmr-nt in
characterized by the presence of numerous ridges, sub-ridges,
narrow V-shaped, minor and major valleys. Majority of these
sub-valleys abut with the major Dachigam valley. A major ridge
with the NW-SE trend is confined to the north of the Dachigam
nallah, which constitutes part of the Dachigam forest area.
This major ridge has numerous sub-ridges which radiate in
various directions giving rise to intervening minor valleys.
The topography confined to the extreme north of the Dal Lake
is separated from this ridge by the Dara N running approximately
in the E-W direction. The Dachigam forest area traced north of
the Dachigam nallah is traversed by a valley through which
flows the Dagwan nallah running approximately in the N-S
direction. Towards north of Mahadeo (3979 meters) the conical
hills with minor basins arc found. The topography north <)f the
Dachigam nallah possess numerous escarpments some of them are
visible along the northern watershed also. The ridges and
intervening valleys swing in their trend. The general trend
is NE-SW.
The topography confined to the south of the Dachigam
nallah consists of short ridges and valleys extending directly
from the southern watershed limit to this nallah. These topo
graphic features run approximately parallel to the Leyichnar
(3412 meters) ridge which has the general trend of NW-SE.
32
The ridges constituting part of the Dachigam forest
have north-south trend in general.
In the extreme east end of the Catchment the Dachigam
nallah flows parallel to a ridge existing along the left bank
of the Dachigam nallah. Few escarpments are also noticed.
Saddle-hillocks with tongue shaped hills and spoon shaped
depressions are noticed near Marsar. South of Nagaberan
Saddle-hillock feature is also noticed.
Strictly the lake Catchment has been divided into two
sub-catchments, four watersheds and thirty eight micro water
sheds (Fig. c and Table- jj ). From the broad
topographic point of view the lake Catchment has been divided
into six sub-catchments (Fig. 5 and Table- III ),
Table-Ill
Sub-Catchments of the Dal Lake Catchment,
_Sub-Catchment_Nomenclature Sj mbol
1. Dachigam Sub-Catchment A
2. Telbal Sub-Catchment B
3. Hillside Sub-Catchment C
4. Srinagar North D
5. Srinagar E
6. Dal Lake F
33
34
T a b l G - I H AREA ESTIMATION OF MICRO WATERSHEDS OF THE DAL
LAKE CATCHMENT,
Catchmen t
Name Code No.
(1 ) ( 2 )
Sub -ca t chme n t
(3)
Wa te r shed Micro-
Code No.
(4) (5 )
- w a t e r s h e d
Area
(6 )
DAL l E Z Z l Z l a
Z l b
Z l a .
Z l a ,
Z l a ,
Z l a
Z lac
Z l a ,
Z l a .
Z l a 8
Z l a .
Z l b .
Z l b ,
Z l b .
Z l b ,
Z l b ,
Z l b ,
Z l b .
Z l b 8
1 6 9 8 . 7 0
1 1 0 0 . 0 0
8 6 8 . 1 4
8 5 3 . 8 6
9 9 4 . 5 9
1 0 0 4 . 6 3
1 0 7 2 . 4 8
1 2 8 8 . 0 7
1 6 1 4 . 2 3
1049 4 .69
1 1 9 3 . 6 1
9 1 6 . 6 8
1 1 4 5 . 3 5
8 1 6 . 1 7
9 1 6 . 6 8
6 6 2 . 6 8
9 7 3 . 9 6
86 2^09
7 4 8 7 . 2 2
c o n t d . .
35
c o n t d , . .
(1) (2) (3) (4) (5 ) (6)
Z2 Z2a
Z2b
Z2a i
Z2a2
Z2a3
Z2a4
Z2a5
Z2a5
Z2a^
Z2ag
2 2 b i
Z2b2
Z2b3
Z 2 b . 4
Z2b3
Z2bg
Z2b^
Z2bQ
Z2bg
^ 2 ^ 0
1 0 6 9 . 9 7
9 6 6 . 9 4
1 2 0 4 . 6 2
8 9 4 . 0 7
1 0 9 2 . 5 8
1 0 6 4 . 9 4
8 4 0 . 7 8
6 6 4 . 40
7 7 9 8 . 3 0
7 9 3 . 5 5
9 1 7 . 20
1 1 0 5 . 6 6
9 1 4 . 6 S
8 0 2 . 6 8
8 6 6 . 4 2
8 5 6 . 3 7
8 28 .73
123 2 . 6 1
1 1 6 7 . 9 7
Z2bj j 7 0 5 . 6 0
Z2b^2 8 7 2 . 6 5 Z2b 2 2 4 3 6 . 0 5
1 3 4 9 9 . 8 7
4 38 • T o t a l a r e a ; Dai (lEZ) 3 9 2 8 0 . 2 8 ( H a )
S o u r c e s D i r e c t o r a t e o f S o i l C o n s e r v a t i o n , J and K Government, S r i n a g a r (Kashmir) .
36
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The present slope characteristics of the Catchment
have evolved through a sequence of events which may be of
endogenic and exogenic in nature including spectacular changes
in folding, faulting and the consequent rejuvenation of drain
age channels with pronounced effects on landforms in general
and on the patterns of slope in particular. This has imparted
the Catchment with topography varying from hills of steep
slope to regions of flatland.
The slope characteristics of the Catchment devised by
Wentworth's method (1930), reveal that the average slope
ranges from 0-4 0 degrees. The average slope around the
immediate vicinity of the Dal Lake varies from 0-10 degrees,
10-20 degrees in the foothills surrounding the three sides of
the lake and from 2 0-40 degrees in the surrounding hill regions
On the basis of slope analysis, the Catchment is divided
into the following five generalized slope categories (Fig. 7).
1. Region of Low Relief or Flatlands (below 5 degrees).
2. Region of gentle to moderate slope (5-10 degrees).
3. Region of gentle to undulating slopes of the foot
hills (10-20 degrees) .
4. Region of moderate to steep slope (20-30 degrees).
'' 5. Region of steep slope of the hills (30-40 degrees).
38
39
1. The region of low relief consisting of low-lying
plains and flatlands is around the Dal Lake where
the average slope remains within 5 degrees.
2. It is an area of gentle to moderate slope (5-10
degrees) mostly found along the Karewa lands. A
heavy sub-soil, coarse-textured surface soil, further
becoming heavier with depth are the characteristics
of this region.
3. The region with gentle to undulating slope (10-2 0
degrees) is a transition zone between the hills and
the lake floor. This region embraces the soils on the
slope of the mountains.
4. The region of moderate to steep slope (20-30 degrees)
extends over a vast area of the Catchment,
5. The region of the steep slope hills (30-40 degrees)
is too steep. With increasing altitude and gradient,
it remains covered with perennial snow. The main river
and some of the nallah of the Catchment are mostly fed
by this snow field.
Table- IV indicates the average slope of each
segment of the sub-catchments of the entire Dal Lake Catch
ment. The angle of slopes go on decreasing in magnitude
towards the Lake shores on all sides. Each sub-catchment
baring Dal Lake has more than one slope region. The Dal Lake
region is a flat sub-catchment and serves as a datum. The
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41
relationship of slope categories with other physical factors
of the lake Catchment has also been established (Table- V).
Climate :
The climate of the state of Jammu and Kashmir varies
from tropical to arctic. For Srinagar and Dal Lake, the
climate may be described as temperate for most of the year.
The Kashmir in particular is very less affected by the mon
soons, local rains in lake Catchment during summer is a
prominent feature. The annual rainfall per annum at Srinacjar
is 650 mm and at Dachigam 870 mm. An average of 600 nm of
snow falls in Srinagar during the winter but the snowfall on
the higher slopes is much heavier. In the upper end of the
Dachigam, snow lies on the ground for nine months of the year.
The temperature ranges from an average daily maximum of 3l°C
and minimum of 15 C in July to an average daily maximum of
4 C and minimum of -4 C in January. The maximum daily humi
dities range from 80 per cent to 90 per cent throughout the
year and drop to approximately 70 per cent at night during
the winter and 4 0 per cent during the sutmner. The tsvopottana-
piration from the Dal Lake is assumed as 815 mm, for open
water. Floating Garden and marsh areas. The strong winds are
very uncommon and at Srinagar the wind strength seldom exceeds
a 42
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43
5 km. per hour. In general* the breezes are north to north
west in direction (Enex, 1978).
Hydrology :
The Telbal nallah carries water discharge of 60 cumecs
whereas the peak flood discharge of the nallah has been
reported at 170 cumecs. The annual average water inflow is
estimated at 292 x 10 cubic meter of which 80 per cent is
contributed by the Dachigam nallah and the 2 0 per cent by
the lake side Catchment drainage and rainfall. The annual
average outflow at the two outlets (Nallah Amir Khan and Dal
Gate) has been estimated at 261 x 10 cubic meters. Hence the
water which could be retained within the lake body is 31 x 10
cubic meters.The water levels in the lake have varied over a
range of 1.5 meters during recent years with the deepest water
level recorded at 1580.69 meters and average water level
standing at 1583.43 meters (Enex, 1978).
Drainage s
The Dal Lake Cfitchment is bounded to the north and west
by the Sindh drainage basin, to the east by the Liddar basin,
to the south by the Arpal basin and the southwest portion is
44
connected to Dal Lake by the loop of the Jhelum river.
Dachigam nallah being the chief river In the Catchment have
a net flow length of 39.0 kms., originates from the Marsar
(snow and glacial fed lake) in the eastern sector of the
Catchment and enters the Dal Lake at Telbal on its northern
side in the western sector of th*» Catchment. This feeding
reservoir to the lake body occur at an elevation of 3781
5neters. All other drainage systems from the slopes of Harawar,
Burzakut, Mahadeo and Sarbal escapes into the Dal Lake through
the Harwan and a number of other mountain torrents.
The Dachigam nallah flows from east to west and the
streams which discharge into the nallah are both perennial
and intermittent. Besides intermittent streams some eighteen
perrenial streams drain into the Dachigam nallah; amongst
them the noteworthy are Dagawan nallah, Wagahat N, Manyu N,
Drog N, Mahadeo N, Mulnar, Dara Nar, Nambalan N, and the Grat
Nar. The terrain to the north of the Telbal sub-catchment
gives birth to Ruskhan Nar and Sod Nar which ultimately find
their way to the lake either by surface drainage or by sub
terranean flow. All these streams originate from an elevation
of above 3000 meters.
The arcuate ridge to the east of the Dal Lake serves
as a water divide in the Catchment. Most of the streams
originating from this ridge enter directly or indlr<rctly to
45
the Dal Lake whereas some of them discharge into the
Dachigam nallah. The streams which enter the Dal Lake
directly from its east side after draining lake hillside
sub-Catchment drain via vegetable gardens, Shirazi Bagh,
Naupura and Lam, The streams which enter the Dal Lake from
its northern shore drain via Dadu Mahal and Habak Hamhor.
The river channels of the lake Catchment have disparate
drainage patterns because the fluvial processes being depen
dent on the quantum of slope and the nature of the rock
material which differ from locality to locality within the
Catchment. The Catchment possess the drainage mostly of
consequent origin. The Catchment exhibits dendritic, parallel.
Trellis, Irregular and radial patterns. The drainage around
the Dal Lake and the Marsar display centripetal network.
(Fig. 8).
Like all other networks, the streams also have their
own peculiarities which are determined by a set of physical
factors, such as structure, altitude, gradient and climate.
They change in time and bring about a consequential change in
the form of landscape with far-reaching repercussions on the
hydrological processes. The intricacies of this relationship
between the form and the process can best be appreciated by
employing the tools of morphometric analysis. Such an exercise
may yield a good deal of useful data pertaining to the drainage
46
47
character and intrinsic relationship between the area of
the Catchment basins of each of the component streams and
the discharge of the trunk stream (Raza et al.» 1978),
The streams in the Catchment area are of 1st, 2nd, 3rd,
4th and 5 orders. Within the whole Catchment streams of the
1st and 2nd orders predominate. The drainage basin characet-
eristics of the Catchment (Raza et al., 1978) are indicated
in Table- vi Within the Catchment the bifurcation ratio
is the highest between 1st and 2nd order streams and the lowest
between 3rd and 4th order streams. The Catchment has average
3.00 stream bifurcation ratio. The values of drainage density
(•3:LK/AK) and texture (NU/AK) for the Dal Lake Catchment have
been found as 0.38 km. and 0.27 per square km. area respectively,
S t r e a m O r d e r
1
2
3
4
5
Dal Lake
NundDer of s t r e a m s e g m e n t s
73
19
6
3
1
T o t a l
- 102
T a b l e - V I
D r a i n a g e B a s i n
B i f u r c a t i o n R a t i o (Rb)
3 .84
3 .16
2 . 0 0
3 . 0 0
Average
« 3 . 0 0
C h a r a c t e r i s t i c s .
L e n g t h of s e g m e n t s i n e a c h o r d e r and a s % of cumu l e n g t h L e n g t h (km.)
8 9 . 0 0
2 4 . 0 0
9 . 0 0
1 2 . 0 0
1 0 . 0 0
C u m u l a t i v e l e n g t h
= 1 4 4 . 0 0
l a t i v e
%
6 1 . 8 1
1 6 . 6 6
6 . 2 5
8 . 3 3
6 . 9 5
Mean l e n g t h of s e g m e n t s (km.)
1.22
1.26
1 .50
4 . 0 0
1 0 . 0 0
(After Monis Raza and others, 1978).
48
From the Harwan reservoir and the Telbal nallah at
Harwan a network of the irrigation canals have been taken
for irrigation purposes to the Telbal sub-catchment and the
hillside sub-catchment. These waters after irrigating the
arable lands within these sub-catchments contribute to the
groundwater regime of the catchment through the processes of
infiltration and interception.
Apart from certain springs reported to emanate from
lake bed, the water tables cut the surface profiles within
the Catchment at numerous places resulting in the outflow of
groundwaters in the form of seepages and springs. The Dal Lake
Catchment is characterised by the presence of numerous springs
probably by virtue of its ideal hydrogeological conditions
prevalent in the various lithological units. Amongst them the
notable springs are located at Baba Gulamdin Sahib Shrine.
Ziarat, Pari Mahal, Cheshraashahi Garden, Isherberi shrine
(Gupt Ganga) and spring located near Shalimar. Others occur
either at the headwaters or tailwaters of various streams
(Wars), contributing to the Telbal nalla. In the whole
Catchment area outside lake body as many as nineteen springs
(Fig. 9 ) have been noticed and their position with
reference to the metric grid system is noted as under j-
91 3 12 3; 81 0 19 0; 80 4 20 3; 80 3 18 6? 79 7 11 9
(Baba Ghulamdin Sahib); 79 2 21 0; 79 5 21 8; 78 7 21 8
49
9 TUBEWELL
• 0 • EXPLORATORY B.H. 4 SPRING
' ' ~ - WATERSHED
FIG. 9 MAP SHOWING DUGWELL, TUBEWELL, EXPLORATORY BORE HOLE AND SPRING LOCATIONS AROUND DAL LAKE
50
(Ziarat Spring); 77 0 10 3 (Pari Mahal Spring); 78 0 10 7
(Cheshmashahi); 76 4 16 8 (Near Shallmar); 76 3 16 0
(Isherberi Shrine); 74 9 20 6; 75 0 21 4; 75 4 22 8;
74 8 22 7; 73 7 21 0; 74 0 23 3; and 72 9 22 5.
ENVIRONMENTAL HAZARDS J
The Dal Lake Catchment is faced with numerous environ
mental hazards. These include deforestation, erosion, intensive
agricultural practices,urban impact, waste disposal and deve
lopment of floating gardens. These hazards in the Catchment
have resulted in sedimentation, weed growth, water quality
deteoration and reduction in lake dimensions. This all
phenomena is illustrated in Figure- ig . The hazards
occurring are briefly discussed.
Sedimentation t
The sediment yield from the surrounding Catchment and
its subsequent deposition within the Dal Lake body is the
prime cause for its reduction in size and depth. The silta-
tion is governed by geology, topography, climate and vegeta
tion in the Catchment area.
51
FIG.10 DAL LAKE CATCHMENT H A Z A R D S INDICATING
E N V I R O N M E N T A L DEGREDATION UPON LAKE WATER BODY
52
The Catchment area of Dal Lake exposes granites,
quartzites, slates, phyllites, basalts, sandstones, clay-
shales and limestones. Compared to these harder rocks, soil
units, viz., sandy, silty and pebbly conglomerates, boulders,
pebbles, terraces, river borne sands and materials on slopes
are the other units susceptible to weathering and erosion.
It cannot be ruled out that the slates, phyllites, clay-
shales, limestones, basalts and its weathered residue and
sandstones may also contribute particles for bed load and
matter in solution and suspension. The softer units constitute
about 27 per cent of the total area whereas harder units
constitute about 73 per cent.
The soil developed on volcanic rocks is very shallow.
It is light sandy loam with enough clay, and their water
holding capacity is very poor. By constant scuffling of
cattle, the surfaces become dusty making the soil vulnerable
to easy transportation and sedimentation. Dagwan nallah is the
main cross drainage of Dachigam nallah within the interior of
the Catchment and flows through basalts, limestones, calc-
shales, sandstones and alluvium. The Catchment area experien
ces heavy snowfall which also helps to disintegrate the
country rocks. The rain coupled with strong winds and steep
gradient activate the erosion and subsequent deposition
(Srivastava, 1982).
53
Major carrier of sediments to Dal Lake Is Dachlgam/
Telbal nallah which drains almost the entire length of the
Catchment. The total volume of silt deposited in the Dal
Lake by the Telbal nallah is 36200 cubic meter per year
(Enex, 1978).
URBAN IMPACT :
The Dal Lake Catchment sustains a population of
137474 as per 1981 census data (District Census Handbook,
1982). Within the Catchment urban, rural and transition of
two i.e. semi-rural or semi-urban constitute the cbmplexion
of population. The majority of the people have settled on
the shores of the lake particularly in south and west of the
lake body. There has also been a tendency to' transform the
land lying to the east and north of the lake into the urban
built-up. The lake is surrounded by urban built-up with poor
facilities, therefore, the rural scene is generally v.'itnessed
far beyond the shores of the lake. The lake body itself sus
tains boat population, and a few dwellings on the Floating
Garden strips. Besides day to day thrust of native population,
there is an impact of international tourists as well upon the
lake body. Broadly the population of the Catchment can well
be categorized as under (District Census Handbook, 1982).
54
1. Urban population 121891
2. Rural population 9001
3. Boat population 6582
Total 1,37474
The areas in the immediate neighbourhood of the Dal
Lake both low lying (reclaimed in the recent past along the
lake peripheries) and high lying have been divided into
following population sectors (Table-VIl).
Table-VII
Sectorwise Population around Dal Lake.
Sector Population (year 1981)
1. Cheshmashahi 11750
2. Nishat-Shalimar 1866
3. Shalimar-Telbal 5171
4. Telbel-Naseem bagh 2904
5. Naseerabagh-Ashaibagh 5166
6. Ashaibagh-Dalgate 35771
7. Dalgate-Cheshmashahi Data not available
(Source : Project Report, 1982).
55
Waste Disposal :
The Dal Lake which is a recipient of every sort of
waste produced within the Catchment, receives domestic
effluents, sewerage and sullage from the urban and non-urban
sources from within and outside the lake body. The Dal Lake
has Infact become a dumping ground for the refuse of the
people surrounding It. Besides, various chemical substances,
fertilizers and pesticides from nearby agricultural fields,
orchards and forests together with the animal droppings from
the Dachigam sanctuary are carried to the lake body by various
surface, channels and sub-surface waters.
About 1800 houseboats in the lake provide boarding
and lodging to the tourists due to which about 95 tonnes of
sewage alone gets deposited in the lake bed every year
(Srivastava, 1982).
Population sectors in close proximity to the Dal Lake,
discharge directly all types of pollutants in various forms of
refuse into the lake body.
Floral Growth and Development of Floating Gardens :
Phytoplanktons (Diatoms, Blue-green and Green Algae),
Zooplanktons (copepods, rotifers and protozoans), and Macro-
phytea (mostly Salvinla nnd rooted weeds) ar>* th« plnntn which
56
grow on the Lake bed and have extensive distribution in the
lake body. Amongst them Macrophytes have high production,
dense and extensive growth.
These aqueous plants first develop in marshy and dirty
water, shift to clean water by winds and grow rapidly by
absorbing more and more water. These have been found to
contain about 95 per cent water by weight. They develop twice
within a week and 100 times in about six weeks thereby reducing
the volume of water body. These weeds decay and get deposited
on the lake bed. Floating Gardens have grown to about 200
hectares along the western and southwestern shores of Dal
Lake (Srivastava, 1982),
Extensive development of weed growth occur within the
lake body on account of refuse disposal and siltation besides
the release of nitrogen and phosphorus by the agricultural
practices on the Floating Gardens.
The Dal lake which has shrinked in dimension (size and
depth) attained various shapes from time to time by natural
and man induced causes. The size of the lake has been grossly
reduced by man made activities. Unplanned developmental acti
vities in and around the lake body coupled with malutilization
of the lake bed and Catchment tracts are the prime factors
responsible for the lake decay and water quality deterioration.
57
The palaeoenvironment of the Dal Lake and its environs
can be best understood by making a retrospective account of
the developmental activities that have occurred in and around
the lake body. Space does not permit to record the full account
here, yet it could be ascribed to the periodic attacks of
nature and man (Fig. 11 ) which gave rise the' present
configuration to the lake body.
To conclude with, the lake body has reduced in dimension,
its hydrology and hydrogeochemistry have been altered. Sedi
mentation, deposition of decayed weed and solid waste disposal
has left only 2.74 meters (on an average) deep water body
which was formerly six meters (on an average) deep. Extensive
encroachments, infrastructure and development of floating
gardens during the last thirty years have resulted in dimini
shing the Dal Lake area from thirty two sq. km. (in the year
1947) to eighteen sq. km. (presently), involving about half
the reduction in its area. Thus an area of 15.42 sq. km. h; s
been left as open water area within the Dal Lake body excluding
permanent land features (islands, roads and marshy areas).
About one hundred commercial establishments, two thousand
residential buildings, floating gardens on two hundred
hectares and cultivation on four hundred hectares have also
helped in reducing the size of the Dal Lake. Unplanned
infrastructure has imparted sub-basinal status to the Dal
58
Su la iman H i l l o c k
6 t h C e n t u r y I S t h C e n t u r y
19th Century Present Day
FIG. 11 SCHEMATIC PLANS SHOWING EVOLUTION OF DAL LAKE S O U R C E : MASTER PLAN SR IN AGAR CITY-1971
59
Lake body, thus restricting free flow of the water having
stagnant zones in the lake particularly in the west and
southwest. Population sector six and low lying areas around
lake periphery put maximum and alarming deterioration and
damage to the lake body. Domestic effluents (detergents and
solid Waste disposal), dyeing, fur dressing, laundary acti
vities, agricultural wastes (irrigation return flows, animal
wastes, application of fertilizers, soil amendments, pesti
cides and insecticides) and metals from natural sources all
contribute to the enhanced metal levels. The outflux of
nutrients (N, P and K) and other metals does not take place,
leading to the ageing or eutrophication, deterioration in
water quality and enhancement in metal levels in the lake
sediments.
60
CHAPTER - IV
LANDUSE OF THE DAL LAKE CATCHMENT
This chapter deals with both the existing landuse
pattern and the suggested landuse set-up of the catchment.
Various landuse practices often alter and affect the hydro-
geochemistry of natural waters in a drainage basin particu
larly of a closed or partially closed ecosystem such as a
lake. They too bring changes in the lake ecology and lake
morphology. The suggested landuse set-up have thus been
proposed to contain such changes that may further degrade
the lacustrine environment.
EXISTING LANDUSE I
The Dal Lake Catchment has an areal extent of 381.44
sq. km. Landuse map of Dal and its immediate environs
(Fig. 12 ) prepared from the satellite imageries and aerial
photographs, depict various categories of land under use
around the Dal Lake body. Estimation of the area of the
landcover feature around the Dal Lake, formulated with the
help of remote sensing data is indicated in Table- VIII.
The entire catchment has been studied and data plotted on
61
0 ^0-5 IKM 1 I J
i --11 II
II
J- I
FLOATING GARDENS
ORCHARDS
CULTIVATION ON HILL SLOPES
BARREN HILLY TERRAIN
I ^ I ROAD
CANAL
SETTLEMENTS
WATER BODIES o> FIG.12 LAND USE MAP OF DAL LAKE AND ITS IMMEDIATE ENVIRONS
(AFTER M.A.KAWOSA, Dr.Pallaria et,al,1987 Space application, centre, Ahmedcbad)
62
Table -VII I
Area E s t i m a t i o n of the Landcover F e a t u r e around the Dal Lake .
S.No. F e a t u r e s Area Remarks ( sq .km. )
2 .
3 .
4 .
5 .
6 .
7 .
8 .
9 .
10 .
1 1 .
1 2 .
To t a l a r ea mapped around 80 .00 t h e Dal Lake
Orchards
Crop fields
Crop (Paddy) land
Terrace cultivation
Marshy area
Garden
Floating Gardens
Nagin Lake
Water Body (western of Gagr:
Eroded area
Township/settlementi
side Lbal)
s
7.00
3.00
8.00
2.00
0.50
0.50
7.50
1.00
0.50
8.00
43.00
Apple
-
-
-
-
-
Vegetables
-
-
-
^
and i n f r a s t r u c t u r e
(Af ter Kawosa, Pa l la r ia e t a l . , 1987)
Source t D i r e c t o r a t e of Ecology, Environment and Remote Sens ing , Jammu and Kashmir Government, S r i n a g a r (Kashmir ) .
63
the toposheets on 1 « 50,000 scale. By this landuse and
landcover map of the Dal Lake Catchment has been prepared
(Pig. 13 ) delineating various classes of land presently
under use within the catchment area. Areawlse landuse
figures have been estimated for the entire catchment as
shown In Table-IX.
The catchment has been utilized and managed for variety
of purposes. Out of the total areal extent of 381.44 sq. km.,
the catchment has a vegetative cover over an area of 104.04
sq. km., barren with rocky exposures with an area of 190,55
sq. km., agricultural land 43.73 sq. km, and built-up land
25.08 sq. km. Besides this the water bodies occupy an area
of 19.40 sq. km. Out of which the Dal Lake alone constitutes
18.43 sq. km, and the other two water bodies Nagln and Marsar
lakes occupy an area of 0.60 sq. km. and 0.37 sq. km.
respectively. Broad spread of the various categories of land
under use within the lake catchment is briefly discussed.
Forest Land or Land under Vegetation s
Forest land is mainly represented by the Dachigam forest;
spread to the north and south of the Dachigam nallah in the
interior of the catchment right from Harwan upwardiS. It grows
mostly pine trees (kairu/kall) besides broad leaved and
64
V
65
Table-IX
Landuse Figures of Dal Lake Catchment,
Land Category Area Area (km^) (%age)
Remarks
1. Land under 103.04 Vegetation
2. Barren/Rocky 190.55 Land
3 . Agr icu l tura l 43.37 Land
4 . Bui l t -up Land
25.08
5. Water Bodies
a. Dal Lake 18,43
b. Nagin Lake
27.04 Mainly Dachigam Forest area.Fairly dense mixed Jungle. Broad leaved, conifers and pine trees (kairu),
49,95 Constituting Northern,Eastern watershed and arcuate ridge lying East of Dal Lake. The area is devoid of vegetation. The land is mostly rocky and covered with soils at some places.
11.37 Land occupied by paddy and maize fields, vegetable gardens, orchards,gardens and parks, and infrastructure (roads and hotels) lying to the North, East and Southeast of the Dal Lake body. This figure includes land which is exclusively outside the lake body and is other than the reclaimed in and around Dal Lake. On open agriculture land scattered population settlements has risen.
6,57 Occupied by townships, human settlements, and infrastructure developed outside the lake body. Encroached and reclaimed lands and floating gardens developed within the lake body. Outside inhabitated land stretches lie to the North, Northwest, West, Southwest, South and Southeast of the Dal Lake. Out of these stretches North, West and Southwest are intensively congested and populated.
4,83 Open lake water areas, permanent land features (islands and roads) and marshy areas within the lake body.
0.60 0.37
i81,44
0.15 0,09
100.00
Total Catchment
Open water a r e a s . Open water a r e a s .
Area * 381.44 km^ (38144.00 hec ta res )
66
conifers. Dachigam Is fairly dense mixed jungle having Cedrus
deodara in higher reaches. The forest area also grows bushes,
shrubs and open scrub. The world famous sanctuary called
Dachigam sanctu€iry lies within these forests.
Barren Land :
The barren land covers an area of 19 0,55 sq. km. which
account for half of the total catchment. The barren land is
represented by northern, eastern watersheds and arcuate ridge
lying towards east of the Dal Lake including spurs and hillocks
The land is mostly rocky but at places it is covered with thin
soil. Besides, the slopes are capped by debris.
Hence, in general the north facing slopes and watershed
limit in the catchment have a vegetal cover, while as the
slopes facing south are steep and the watershed limits are
devoid of vegetation and are barren. The rugged terrain
abounding the forests have a thin cover of soil layer at the
higher reaches and its thickness increases towards the lower
slopes of the Dachigam valley.
Agricultural Land s
Agricultural land is the one other than the reclaimed
land in and around the Dal Lake. This land is confined to the
67
north, east and southeast of the lake body. It also extends
into the Dachlgam valley and Dara Nar. To the north of the
lake, minor sub-valleys of the northern watershed limit are
occupied by these agricultural land patches. Few and far
between settlements have also risen on such lands which are
of tiny nature.
An area of 43.37 sq. km. has been utilized for agri
cultural purposes in the catchment area on the pedological-
cum->topographical considerations. The land under this category
consists mainly of agricultural, horticultural and florl-
cultural areas. The agricultural land produces paddy, maize
and vegetables; horticultural land produce fruits; and the
floricultural land consists of gardens (including famous Mughal
Gaxxlens), parks and hotels.
The horizontal and gently sloping terraces around the
Dal Lake are extensively utilized for paddy fields, vegetable
gardens, orchards, famous Mughal Gardens, parks and hotels.
But terraced cultivation is a prominent feature seen in the
neighbourhood of Dal Lake. Terraces yield wet and dry culti
vation crops including vegetables. Mostly lower terraces grow
paddy and higher mountain fringes produce maize.
68
Built-up Land :
The built-up land comprises townships, human settlements
and infrastructure outside the present lake water body. It
also includes reclaimed land along the lake peripheries, and
floating gardens within the lake body. Although urban and
rural settlements have taken place along and far off lake
shores simultaneously, however, human encroachments for
dwelling constructions along the lake shores is a very
prominent feature. Some 2000 residential buildings are
located in the close proximity of the lake water body.
This figure also includes Floating Gardens that have
been developed within the lake body. This has agricultural
utility for the people who inhabit near the lake. North of
the Dal Lake, the Floating Gardens have developed even up to
the low lying areas of Nishat. These Floating Gardens are
prominently seen towards the west and southwest of the lake
body. These land strips locally called Rudh, Dem and Daji are
separated from each other by narrow waterways. These floating
gardens have come up within the lake body in west of Dal Gate,
Nowpora, Karapur pain, Kotarkhan, Doladem, Malpur, Lati Mohalla,
Mir Behri, Mantimahal, Takia Lai Shah, Ashai Bagh and Nandapur.
A few human dwellings and tourist resorts have developed on
these land strips. Such type of gardens are also seen to the
east and southeast of the Nagin Lake.
69
The area lying between the floating gardens and older
terrace towards the northern and northeast portion of the
lake has been converted for habitation purposes. The habita
tion which have thereby grown outside the lake body are to
the north of Nishat, Isherberi, Dadu Mahal, Shalimar Ghat
area, Gaomarg, Batpur, Gand Telbal, Habbak Hamhor and Habak.
The congested population settlements which have come up in
northwest and west of the lake basin are Nasim Bagh, Hazrat-
bal, Nagin, Rainawari, Khaniyar and Daulatabad, Isolated and
congested population settlements which have come up in south
east of the Dal Lake are Gupkar and Buchwara. Bren, Mansgam,
Lam, Banigam, Pazwalpur, Harwan and Mutbagh are some of the
examples of similar type of congested habitations,built-up
outside the lake body representing both urban and rural
settlements.
Water Bodies :
Dal, Nagin and the Marsar Lakes are the water bodies
of the catchment, besides Dachigam nallah with its numerous
streams (perennial, intermittent and ephemeral) also drain
the catchment. These three lakes occupy an area of 19,40
sq. km., out of which Dal, Nagin and Marsar lakes represent
18.43, 0,60 and 0.37 sq. km. area respectively. They constitute
about 5.07 per cent of the total area of the catchment; of which
70
the Dal and Nagin lake bodies together form about 5 per cent
of the total catchment area. The open water of 18.43 sq. km.
is being represented by Dal Lake excluding floating gardens
but including permanent land features such as roads, islands
and marshy areas within the lake body. Amongst isolated
features the noteworthy are Nehru Park, Sonalank, Rupa Lank
islands and Sut-i-Chodri causeway etc. within the lake body.
Marshy areas have willow plantation. These permanent land
features have an approximate area of 4 sq. km. The lake body
also sustains 1800 house boats and 100 establishments.
SUGGESTED LANDUSE s
Keeping in view the drawbacks/defects with the existing
landuse, and the issues of environmental concern associated
with the present landuse set-up, it is appropriate and perti
nent to plan the existing landuse as described below. The use
of land within the catchment has been suggested with a view
to minimize the future environmental degradation/hazards.
This is also based on natural potential or suitability of
the particular land class.
71
Forest Land or Land under Vegetation j
The deforestation and grazing activities enhances the
chances of getting new sites or localities exposed to the
phenomena of the geological processes, namely, weathering
and erosion. These activities be stopped and deforestated
patches be afforestated.
Barren Land t
Enormous portion of the catchment is barren and rocky
amounting to about 50 per cent of the total area of the
catchment. The barren areas are currently subjected to
weathering processes. The diurnal variations in temperature
accounts for the physical disintegration of the naked rocks
at the higher altitutde and the chemical weathering takes
away material in solution. Finer material is taken away in
suspension as well as carried as bed load.
The soil covers which often get removed by the processes
of mass-wasting and erosion, should be so protected and the
land under this category should not be allowed to increase
in area. The method of afforestation be employed so as to
bring more areas of this category under vegetal cover.
72
Agricultural Land :
The land occupied by the vegetable gardens discussed in
the agricultural land earlier, be planned for gardens, parks
and city forest. Limited type of agriculture be practised in
the immediate proximity of the lake particularly where the
water tables are shallow. Scattered habitations be disallowed
on the agricultural land.
Built-Up Land s
Lake shores be demarcated by way of metalled roads and
stone bunds as existing from Dai-Gate to Nishat. This road
be continued from Nishat to Nasim Bagh defining its northern
foreshore. The western foreshore be defined by similar type
of structures from Khonakhan to Ashai Bagh. Beyond these fore-
shores the open lands be developed as gardens and parks, land-
scapically well architectured that would serve, as future
viewing spots of the Dal Lake for enjoying its aesthetics
and would be to avert bank erosion of the lake body.
Area for desilting tank near the northern foreshore of
the lake at Telbal be reserved for its construction to check
the silt within the lake body.
73
The population built-ups be provided with the proper
sewerage arrangements finally connected with the sewerage
plant outside the lake catchment in order to preserve the
soils around the lake which serve as good water bearing
horizons.
The floating gardens and population settlements within
the lake body including at the south of the lake near the
Dalgate be totally removed, to ensure the natural flush out
(outflux) of pollutants from the lake body.
Lake Water Body s
The physical barriers in the form of roads and tiny
settlements including hotels should also be removed from the
lake body so as to enable the free flow of lake waters. House
boats within the lake be aligned near the newly defined
western foreshore connected with sewage arrangements. This
would restore at least the lakes'one body status and abolish
sub-basins.
74
CHAPTER - V
GEOLOGY OF THE DAL LAKE CATCHMENT
In the present chapter, an attempt has been made to
establish the stratigraphical succession, geological charac
teristics and areal distribution of the various lithounits
in the catchment. Besides, generalized weathering character
istics of the lithounits and mobility of the metals in the
catchment has been dealt with. The mapped geology is based
on the previous geological mapping of Srivastava (1982).
The Dal Lake catchment encompasses granites, slates,
quartzites, phyllites, basalts, sandstones, shales, lime
stones, conglomerates, boulders, pebbles, cobbles and river
borne sands ranging in age from Cambrian to Recent (Fig. 14 ).
These are lithounits and deposits of Palaeozoics, Mesozolcs
and Cenozoics (Quaternary only). The Catchment is
devoid of the Archaeans, Precambrians, Cretaceous, Volcanics,
Tertiary deposits but the granites are believed to be of
Tertiary age and occur as intrusives. Terraces, Alluvial Fans,
Talus Cones are the landforms resultant of Geomorphic processes
developed during the Quaternary period whereas the debris and
scree of Recent to Sub-recent origin rest on the parent rocks
in the Catchment.
I l . l 1 1 1 1 1 1 mmm
.'iV,i I I I /
S'l'i'l
. > > ^^,->- > - , " , " ' - < ; - < > - V > =-
t:
111 «I 1/1 O
^
76
The geological map (Fig. 14 ) prepared, depicts the
lithounits which characterize the catchment. The geological
mapping has been conducted on 1 j 50,000 scale and is of
reconnaissance nature. Table- X indicates the Geological
Succession of the Catchment.
Table-X
Geological Succession of the Catchment
CENOZOIC ( QUATERNARY)
MESOZOIC
PALAEOZOIC
Recent to Sub-Recent
Pleistocene
Jurassic
Triassics
Permo-Carboniferous
Upper Carboni ferous to Peirmian
Upper Carboniferous
Cambro-Silurian
(?)
Scree and Alluvium
Karewas
Panjal Traps
Agglomera-tic Slates
Slate Series
Granites
(Boulders, Pebbles, Terraces and river borne sands)
(Sandy, silty and Pebbly conglomerates)
(Limestones with Shales)
(Mainly Limestones)
(Sandstone, Clayshale and Limestone)
(Quartz Basalts)
(Mainly Slates)
(Quartzites, Slates and Phyllites)
(Unclassified, probably Intrusives).
(After S.K. Srivastava, 1982)
77
Areal extent and percentage-wise distribution of the
various lithounits in the Dal Lake Catchment has been evaluated
and is given in Table- XI From the analysis it is stated that
the Panjal volcanics occupies vast tract of the Catchment to
the extent of about 62 per cent of thp total area, followed by
alluvium (both old and modern) which is of the order of about
22 per cent of the total area. Limestones, shales and sandstones
of Palaeozoic and Mesozoics form about 10 per cent, whereas
Cambro-silurian slate series and unclassified jEfcrrm -fe&g together
form about 2 per cent of the Catchment. vV '' ^^
in / Acc No. >
Areal and Percentagewise D i s t r i b u t i o n o|f|^Nt^>lJftlts i n the Lake Catchment '^ .
y Areal Ex ten t j 'Pe rcen tage L i t h o u n i t s Jf ( s q . km.) X
1. Granites
2. Slates, Quartzites and Phyliites
3. Agglomeratic Slates including Ash beds
4. Panjal Traps (Quartz-basalts)
5. Permo-carboniferous (sandstone, clayshale and limestones)
6. Triassic Limestones
7. Jurassics (Limestones with shales)
8. Karewas (Sandy, silty and pebbly conglomerates)
9. Scree and alluvium (Boulders, 50.003 13.10 Pebbles, terraces and river borne sands)
381.44 99.86
2 . 6 7 2 6 . 8 3 6
4 . 5 6 3
2 3 9 . 8 6
5 . 0 2 3
2 3 . 5 8 0
1 2 . 2 3 7
3 6 . 3 1 2
0 . 7 0 1 .79
1.19
6 2 . 8 8
1 .31
6 . 1 8
3 . 2 0
9 . 5 1
78
The various lithounits occurring within the Catchment
have been grouped era-wise and are described with their chief
characteristics in the paragraphs that follow.
PALAEOZOICS :
The palaeozoics which are exposed in the lake Catchment
are the slate - series, Panjal volcanics and sedimentaries
(sandstone, clayshales and limestones) of the permo-carboni
ferous age.
The slate - series which belong to the cambro-silurian
age lies in Juxtaposition to the granites and Panjal volcanics
These comprise slates, phyllites and quartzites. They extend
from Faqir Gujri to Darwain mostly lying to the Dara-Nar.
Some exposures of this formation are also found near Alastung.
The slates are light green and earthy coloured. They are fine
grained and have developed slaty characteristics due to
processes of metamorphism. Due to weathering the surface
colour of these rocks has turned iron-brownish. The phyllites
are green and light greenish coloured. The rock is fine to
medium grained. Iron staining is prominent on the surfaces
of the phyllites. The quartzites are milky coloured, hard and
coarse grained. This series is associated with some sandstone
beds. These sandstones are coarse grained, grey coloured and
79
contain quartz, feldspar and heavy minerals. The rock is
weathered and iron brownish spots are seen on the surface
of these rocks.
The Panjal volcanics constitutes vast expanse of the
lake catchment. They contain obscure exposures of Ash-beds,
Agglomeratic slates and basalts. These volcanics have spread
in geological time span from upper carboniferous to late
Permian/Lower Triassic. The Panjal traps lie at the top of
the agglomeratic slates whereas ash beds underlie the
agglomeratic plates. The traps form the predominent unit
of the volcanics.
The Ash beds are typically seen near the Mansgam,
Bren, and Sodinar. These beds are earthy coloured, nodular
and having spongy characteristics. The agglomeratic slates
occur on the northern and eastern fringes of the Sulalman-
Hillock. They outcrop along the base of the hill bordering
the Dal Lake from Gupkar to the Shalimar Garden. The out
crops of slates at Bren and on the Spur about midway between
Nishat and Isherberi hills are specially well exposed. The
outcrops of Cheshmashahi to Shalimar village are thin to
thick and are linearly displayed. They also occur to the
north of village Bakra along the irrigation canal and near
village Darawain along the Dara Nar. The agglomeratic slates
are grey, black and greyish black in colour. These are fine
80
to coarse grained, feebly metamorphosed, weathered and iron
staining is prominently seen. The agglomeratic slates yield
rapidly to weathering and often the outcrop is seen as a
crumbling mass of debris.
Ganju and Srivastava (1961) reports that the agglomera
tic slate series is a thick sequence of pyroclastic debris,
several thousand feet in vertical thickness and extending
over a large tract of the country. It builds up many of the
high peaks in the hilly terrains of Kashmir and has played
an important role in the physiographic evolution of the area.
This formation consists of greywackes and slates with angular
fragments of quartz - porphyry, slate, etc.; dispersed through
it irregularly. Two types of agglomeratic slates have been
observed. One is massive and coarse grained variety in which
the constituents of the framework make up as much as 50 per cent
of the rock; the other is a fine-grained, cleavable type with
abundant micaceous and clay like matrix which often exceeds
65 per cent. These two types are clearly distinguishable even
in the hand specimen.
The upper member of the Panjal volcanics famously known
as the Panjal traps are Quartz - basalts, found within the
Catchment. It is well exposed in the Kohi-Maran and Sulaiman
Hillocks, and in ridge east of the Dal Lake. The northern and
eastern watershed mountains of the Catchment are represented
by this lithounit. These traps have non-intrusive character
81
within the Catchment and are thus bedded type. They are
highly jointed and hexagonal pattern of jointing is well
displayed in the Kohi-Maran hillock. The flows vary in
thickness up to six to nine meters.
Varadan (1977) describes the general chnracteristics
of the Panjal traps. They are both massive as well as amyqda-
loidal/ glomeroporphyritic variety is quite common. The
primary constituents are plagioclase and augite dispersed
in a fine grained, semi-crystalline groundmass with mngnetite
and ilmenite as important primary accessories. The ferro-
magnesian minerals have been chloritised or epidotised to
give the traps a green colour, Plagioclase has suffered
widespread alteration to zoisite, epidote and calcite and
augite is replaced by epidote or by chlorite. The original
zeolite infillings of the amygdales, if any existed, have
been replaced by jasper, epidote and chlorite.
Within the Catchment the traps are light green to
green and grey to dark grey in colour and are fine to medium
grained. Coarse grained outcrops have also been observed.
They have porphyritic texture and are silicifled. Glassy
varieties are also found. Traps possess vesicular structure
and the vesicles are filled with the siliceous matter. Due
to weathering, brownish to reddish tints or stains are found
on the rock. The uppermost part of the rock has been weathered
resulting in the development of brownish or reddish layers.
82
The Permo-carboniferous sedimentarles Include the
Gangamopteris bed belonging to upper carboniferous and
Zewan beds belonging to the Permian age. The Gangamopteris
bed is well exposed at the Bren, and Zewans occur in asso
ciation with the Gangamopteris sandwiched between the Panjal
traps and the Triassics along the southern watershed limit.
Near Bren the Panjal traps lie over the Gangamopteris
beds (Gondwana) containing lower Gondwana plants. At Bren,
near Srinagar, a Eurydesma bearing horizon is just below
the Gangamopteris bed. The age of the bed is upper carboni
ferous to lower Permian (Krishnan, 1968), The Gangamopteris
beds are composed of a variable thickness of cherts, siliceous
shales, carbonaceous shales and flaggy beds of quartzite, which
in their constitution are largely pyroclastic (Wadia, 1975).
Within the Catchment the Gangamopteris beds are composed of
sandstones exposed in Bren spur overlain by the agglomeratic
slates and Panjal traps. The sandstones are fine to medium
grained. It contains white to light green coloured- sand
particles. The other accessory minerals are muscovlte and
ferromagnesians. The outcrops are mostly weathered.
The Permian strata popularly known as the Zewan beds
occur in association with the other Permo-carboniferous rock
unit - the Gangamopteris bed. They together exist as a thick
but continuous band having southward continuation up to the
83
Khunmu, a locality of the Vihl district which lies to the
south of the Lake Catchment. This Permo-carboniferous asso
ciation has a northward continuation to the north of the
Dachigam Nallah.These sedimentnrleg fringe around the
prominent Triassic outcrops* and comprise sandstones, clay-
shales and limestones. The base of the Zewan series is
argillaceous and the upper part is calcareous in composition,
the limestone strata preponderating.
MESOZOICS i
Of the Mesozoics, the Triassics and Jurassics found
within the Catchment are represented by limestones and
shales. Jurassics are intimately associated with the
Triassics, often difficult to differentiate the lithologies
of the two periods. They form synclinal core lying conformably
over the upper carboniferous-Permian sedimentaries and the
Panjal volcanics. They occupy about 9 per cent of the geog
raphical compass of the Catchment and are prominently exposed
in the interior of the Catchment on either side of the Dachigam
valley, in the Dachigam forest area and along the southern
watershed of the Catchment. They have northsouth extension
between Mahadeo peak and Burzawas and have eastwest extension
from Waskar and Draphom.
04
Limestones are the principal components of the Triassics.
The rocks are of light blue or grey coloured, compact and
homogeneous and sometimes dolomitic in composition. They are
thin-bedded in the lower part of the system, with frequent
inter-stratifications of black sandy and calcareous shales,
but towards the top they become one monotonously uniform
group of thickly bedded limestones. They bring out strong
relief against the dark coloured, craggy lavas and shales
of the underlying Panjals (Wadia, 1975).
Within the Catchment, the Triassics are main limestones
with intercalations of shales and sandstones. The shales are
greyish and black in colour. These are fine grained with thin
laminations and are associated with the sandstones. The sand
stones are grey coloured, fine grained, hard and superimposed
by the limestone beds. The limestones are fine grained and
the effect of weathering is prominently seen on these outcrops
in the form of white calcic-layers. The limestones are seen
traversed by the quartz-veins.
The Jurassics are represented by the snndnton^-qunrtzito
sequence and the sandstones are associated with thin bands of
limestones. The sandstone unit of the sequence is grey coloured,
fine grained, weathered and containing quartz, feldspar and
heavy minerals. The associated limestones are grey to greyish
black in colour and are fine grained. The quartzites on the
contrary are coarse grained.
85
CENOZOICS X
Tertiary Granites :
The granites occupy a little portion of the Catchment
and are found in the vicinity of Karewa-Faqir. These are
surrounded by the cambro-sllurian formation and are medium
to coarse grained, almost white to grey coloured, containing
quartz, feldspar and biotite. The granites have porphyritic
texture and the phenocrysts of feldspar are prominently seen.
These granites of the Catchment are probably of intru
sive nature which have intruded the cambro-silurian formation.
They have remained unclassified and are regarded to be of
Tertiary aUe. These granites are thought to be an extension
of Kangan granites, found in the Sindh valley which have
banded character.
The Quarternary sequence is represented by the Karewnin
deposits (Pleistocene), Recent to Sub-recent modern alluvium,
talus-scree, slope debris and river borne sediments. These
lacustrine or glacial, fluviatile and gravity deposits togsLher
occupy a wide superficial extent of the Catchment, forming
about 22 per cent of total geographic compass of the Catchment.
86
The present view regards the Karewos as tho surviving
remnants of deposits of a Lake or series of Lakes which once
filled the whole valley-basin from end to end. Lithologically,
the Karewa series consists of blue, grey and buff silts, sands,
partly compacted conglomerates and embeded moraines. The series
is divisible into two stages. Moraines of all periods are
found interstratifled with the finer lake scliments of thf
Karewas at different levels. The Karewas are mostly horizon
tally stratified deposits formed of beds of fine-grained sand,
loam, and blue sandy clay with lenticular bands of gravelly
conglomerates. At some localities the finer sands and clays
show laminations of the nature of 'Varving' — alternating
laminae of different colours and grains indicating periods
of summer melting of ice and of winter freezing (Wadia, 1975).
Upper Karewas are mostly found within the Catchment.
They form uplands and are displayed as Terraces also. These
Karewas abut upon Panjal volcanics and are overlain by the
modern alluvium and other Sub-recent to Recent soil covers.
They are mostly sands, silts and pebbly conglomerates. Thick
deposits of alternating layers of silt and clay are found near
Burzohoma, Inderhoma, Danihoma and Hodura. In the Dara-Nar
they extend upstream up to Chak-i-Dara as glacial terracpf^.
Within the Dachigam valley these deposits extend up to Draphom.
These fluvioglacial deposits are also occurring along and on
R7
the flanks of side valleys which at places join the main
Dachigam valley with a steep cut. They contain fairly greater
amount of clayey matrix embeded with faceted boulders and
pebbles mostly of resistant trap rock. It is not uncommon
to notice larger boulders of the nature of eratics still
available near these deposits.
Slope debris is the soil mantle formed or resting upon
the pre-existing lithounits within the Catchment. Such deposit:
are also found at the foot of hill slopes occurring as scree/
talus composed of angular to subangular rock blocks and
fragments available with clay. The material has loose
disposition.
The modern alluvium is precisely found around the Dal
Lake, in the Dachigam Nallah and Dara Nallahi as the river
terraces and the river borne sediments. The nallah course
associates sediments in the river channels and where the
nallah course broadens river terraces are found. They
constitute rounded to subrounded rock boulders, pebbles
and shingles of trap and subordinate quartzite, limestone,
slates, sand, silt and clayey matrix. The lat^r is rest
ricted to lower reaches. These deposits are also found in
the other tributary valleys of the Catchment.
80
WEATHERING CHARACTERISTICS :
The geochemistry of the lithounits have not been
evaluated, however, metal concentration in the lithology
has been proposed on the tentative basis. The rock units
have been assigned the metal values on the basis of the
metal content in the rocks occurring elsewhere in the
terrestrial environment. Table-Xil have been, therefore,
computed and compiled indicating the tentative geochemical
background levels of the various metal in the lithounits
occurring elsewhere in nature but having almost similar
characteristics as Catchment rocks possess. The Table has
been compiled for correlation purposes only.
Wedephol (1969, 1970, 1972, 1974, 1978) and Todd (1980)
describe the trace and major metal constituents occurring in
various rock forming minerals. The chief mineral con3titur>nty
of the Catchment lithounits are quartz, feldspars, biotlto,
hornblende, magnetite, chlorite, labradoritc, augitc, gypsum
and barytes (as cementing material), calcite and argonite,
and clay minerals. The chemical composition of these mineral
constituents are silicon dioxide; potassium, aluminium
silicates; magnesium, iron, aluminium silicates; hydrated
silicates of aluminium; hydrated iron oxide; iron oxides;
calcium magnesium carbonates; argillaceous, calcareous or
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l i m I) (1. t i 1 ) .. 1 Ki 11 IJ W . (I. . > in lu r. i! . o !•• (0 ri .S <J H a) o
ij n o i : CM .H •,, 4J 8 m II) U > £1 O £ (£ O O • , . -r4 C O E'-4 . i 2 O
0 > i O i n O Q . u i O 10 0) a 4J Q > . 0 w o (.) "< (1-. f. rn J-. rl * 11 •O HI M o 11 Vt •. \-y Vi
O JJ T4 0) O ro ll 10 in m 4-1 rH >. (0 111 0) y w U « >..ri V W O E P E I D d c " " • r ) - y ( ) t l t ) f .V; - .1 111 C 10 ill i: ii "; t) U 'n
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on
magnesium impurities. Besides this clays contaJn alumina-
silicate minerals.
Basalts (Panjal traps) form the bulk proportion
(about 62 per cent) of the lithology, Karewas, alluvium
and scree together form about 22.21 per cent,limestones
constitute 9,38 per cent, sandstones and shales 1.31 per cent,
slates and phyllites 2.98 per cent, quartzites and granites
form only about 1 per cent of the Catchment lithology respec
tively. Hence igneous Terrain is 64.77 per cent, sedimentary
33.30 per cent and the rest accounts the metamorphic terrain.
Karewas, alluvium and scree are softer lithounltn, sVinlor.,
slates and phyllites come next in the soft rock category,
limestones,sandstones and basalts are relatively hard, whereas
granites and quartzites are the hardest. Ferromagneslan
minerals, feldspars, quartz and carbonates form the great
percentage of parental mineral association of the Catchment
rocks.
Prolonged weathering action of the above described
lithounits result in the release of metals in solution,
suspension and alongwith the sediments in the form of bed
load. Physical disintegration yield materials which subse
quently are transported in the form of sediments.These sedim
ents may later on interact with.other phases in lake body
environment. The carbonic acids (H2CO3) created within the
91
weathering environment of Catchment play a vital role in
chemical weathering. Siegel (1974) describes various
inorganic acids (H2CO-, HNO^, HjSO.) of which carbonic acid
is the most important in the majority of weathering environ
ments and organic (humic acids), with solution, other chemical
processes such as hydration, inonization and reduction, and
chelation by organic compounds may contribute to weathering
processes. Theoretical studies which in general show clearly
that intensity of weathering depends on the minerals that
comprise a rock, the rock texture (shape and arrangement of
mineral grains), the climate, the drainage, and the time during
which weathering proceeds, there is an order of elemental
release and, hence, mineral and rock decomposition takes
place. The elements, Ca, Mg, and Na, for example respond most
rapidly to decomposition, followed in rate of loss of K and
Si, all these major elements can be solubilized and carried
from the site of leaching to the immediate hydrologic system.
The exact order of mobility of metals differ, however. In
general the order followed is Ca, Mg, P, Na, K, Fe, Mn and
Al. Fe and Al are least mobile while the alkali ions are most
mobile.
Wedepohl (1969, 1970, 1972, 1974, 1978) describes the
behaviour and mobility of various metals during"weathering
and rock alteration.
92
Chemical weathering of Ca-carbonates and Ca-sulphates
simply dissolve under the influence of rainwater, however,
Ca-silicates are complex to weather. Clay minerals are most
effective in adsorption process of Mg-ions in an exchange
reaction of solutions and solids. Ca is relatively more
mobile than Mg, and Na is more mobile than K, Na and K in
lake waters is dependent upon input and evaporation.
Lead primarily occurs in the structure of K-feldspars
and micas of magmatic and metamorphic rocks, former being
fairly resistant against weathering than later. Minor quan
tities of Pb are contributed to surface water by chemical
weathering. The low lead concentration of lake waters is
probably controlled by lead adsorption on clay minerals
and organic residues, as well as by precipitation of lead
hydroxide, phosphate and/or carbonate under reducing condi
tions, lead sulphide can be the least soluble compound.
The low concentration of Zn and Cu indicates a restric
ted mobility of the metals from places of weathering under
chemical action. Zn occurs primarily in the structure of
silicates and oxides, goes into solution during the chemical
weathering of these minerals. The concentration in weathering
solutions and the distance of transport is controlled by
adsorption, more than by solubility of zinc carbonates,
hydroxides and phosphate. Zn adsorption is strongly dependent
on pH.
93
The geochemical behaviour of iron at the earth's
surface is intimately linked to the chemistries of oxygen,
sulphur and carbon. Primary igneous rock undergo weathering
and disappear in the order such as olivine first, followed
by pyroxene, amphibole and biotite. Carbonic and sulphuric
acids attack, aluminosilicate minerals (clays) are fornned
and dissolved cations, silica and bicarbonates in solution
are released.
In weathering Rb is closely linked to K. Adsorption
may play an important role in the concentration of Rb relative
to K in the late stages of weathering. Rb is usually held in
adsoiTption positions more firmly than K.
During weathering cadmium goes into solution containing
sulphate and chloride under conditions of strong oxidation.
Cadmium forms oxidized minerals, such as CdO and CdCO^.
Cr closely resembles Al and Fe in its chemical
properties and ionic size. It will behave similarly to these
ions during weathering processes, and will be finally concen
trated in clays.
Li during weathering is released from the primary
minerals to the soil solution. It is then removed with tho
soil solution or incorporated in precipitation clay minerals.
Parent rock mineralogy, degree of weathering, time, rainfall,
temperature, topography and run-off are factors which control
94
the concontrntlon of LI metnl in tho wcnthor i-l renlfiun.
In this complex dynamic system it is impossible to predict
tho amount and mobility of Ll other than in a qonernl way.
During the process of weathering the behaviour of Da
is influenced by climate, type of clay minerals (formed by
decomposition of parent rock), amount and kind of organic
material present, sulphur or sulphate content. Ba is adsorbed
from solutions by clays, hydroxides, and organic matter. In
addition to BaSO^ solubility, these processes control tho
amount of Ba present in natural waters. During precipitation
of lake water, Ba is precipitated as barite which usually
occurs disseminated in the calcium carbonate. Ba is used by
lake plants.
95
CHAPTER - VI
HYDROGEOCHEMISTRY OF THE DAL LAKE
This chapter deals with the water and sediment chemistry
of the Lake body. The analytical data of both the water samples
and bottom sediments is presented for evaluating the hydro-
geochemistry of the Dal Lake water body. The major and trace
metal concentration in water and sediment samples have been
determined. Their variation, environmental significance,
probable source and derivation from the Catchment and anthro
pogenic activities, have been studied. The lake water have been
interpreted as a resource for drinking wnt^r supplie.i nn'l
correlation between the water and sediment chemistry was made.
Further, an attempt was made to correlate the metal concentra
tion in waters and sediments with the tentative metal levels
of the parent lithounits.
WATER CHEMISTRY :
Water is a natural solvent which contains numerous
metals both major and trace. The metal concentration in
natural water is governed by several factors like the nnture
of rock types over which it is draining, soil characteristics.
96
contamination due to activities of man etc. Briefly, the
chemical quality of the water is an index of its complex
flow history. In order to study the qualitative and quanti
tative aspects of Dal Lake waters and their spatial variation,
fifty eight surface water samples were collected in and around
the lake body (Pigs. 15 and 16) (Tables-XIII and XIV). Fifty
were collected during the summer season alongwith sediments,
and eight at the four stations established in the four siib-
basins of the lake body for variational studies (four each
during summer and autumn). In all the metals which have been
analysed for the surface waters include Ca / Mg , Na » K ,
COT"* HCOZ* Cl~, SOT, Sr, Pb, Co, Zn, Cu, Mn, Fe, Ni, Hg, Rb,
Cd, Cr, Li, and Ba.
The analytical results of the water thus obtained from
the chemical analysis conducted by the author are given in
Tables-XV, XVI and XVII. Apart from this some physico-chemical
and bacteriological data on the lake is also Incorporated
(Table-XVIIl) from the previous works conducted on the lake
body which is found quite useful and suitable for the
descriptive and interpretational purposes. Paucity of
facilities made it impossible to determine some of the data
and has thus been reproduced from the earlier workers. The
analytical results are discussed below in detail.
9 7
• Sample locations
o Localities
FIG.15MAP SHOWING WATER SAMPLE LOCATIONS IN DAL LAKE BASIN
on
I"
KOH-I MARANI
0750
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• Surnple slalion'j
FIG.16 MAP SHOWING WATER SAMPLE STATIONS IN L A K E SUBBASINS
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106
TABLE^Xy-III 7 PHYSICO-CHEMICAL AND BACTERIOLOGICAL CHARACTERISTICS OF THE DAL LAKE WATERS.
S .No . PARAMETER CONCENTRATION REMARKS
1 . T e n p e r a t u r e
2 . D i s s o l v e d Oxygen
3 .
4 .
5 .
6 .
7 .
T r a n s p a r e n c y ( S e c h i D i s c . )
pH
C o n d u c t i v i t y
A l k a l i n i t y ( a s Ca(
S o l i d s
(as CaCoo )
8 . N u t r i e n t s
Range from 5*C ( i n vd .n te r ) t o S l ^ C ( i n summer)
Range from 1 9 . 0 m g / 1 ( i n summer) t o 7 , 0 m g / 1 ( i n w i n t e r )
Mean r a n g e 0,97m t o t o 2,5m
Range from 7 . 4 t o 9 . 5
136 in icromhos/cm ( a v e r a g e v a l u e ) a t 25 C
Range from 30mg/ l t o 140 m g / 1 .
Total solids, lOOmg/1 (mean)
D i s s o l v e d s o l i d s 9 3 mg/1 (mean)
Suspended s o l i d s 7 . 0 0 mg/1 (mean)
P h o s p h o r o u s
S h a l l o w warm L a k e
W e l l - o x y g o n a t o d
Reasonably clear
Alkaline
Low S p e c i f i c C o n d u c t i v i t y
M o d e r a t e t o Hard
G e n e r a l l y low
H i g h e r n e a r T e l b a i n a i i a h and Dal G a t e
T o t a l p - R a n g e s from 0 , 0 3 1 t o 0 , 1 8 mg P / 1
A v a i l a b l e - R a n g e s P from 0 . 0 0 1
t o 0 . 0 7 5 mg P / 1
N i t r o g e n
A m m o n i a c a l - C o n c e n -NLt rogen t r a t i o n
r a n g e s from 0 . 0 0 5 t o 1.0 mg/1
G e n e r a l l y low
Low
High in Parts of Lake
contd..
c o n t d .
107 •
9 . B a c t e r i a
N i t r i t e - C o n c e n t r a t i o n s N i t r o g e n r a n g e from t r a c e
c o n c e n t r a t i o n s t o 0 . 0 2 mg/1
N i t r a t e - C o n c e n t r a t i o n s N i t r o g e n r a n g e from t r a c e
c o n c e n t r a t i o n s t o 0 . 0 8 mg/1
a ) T o t a l c o l i f o r m b a c t e r i a ^ r a n g e from 640 t o 2 , 4 0 0 MPN/100 ml f o r t h e f o u r s u b b a s i n s o f t h e Lake
b ) T o t a l F a e c a i s t r e p t o c o c c i r a n g e from 0 t o 2 ,400 ' ' ' MPN/100 ml f o r t h e f o u r s u b b a s i n s of t h e Lake
Low
Low
T o t a l c o l i f o r m numbers a r e h i g h e r i n b o u l e v a r d a r e a w h e r e h o u s e b o a t s a r e h i g h e r i n numbe r .
Some f a e c a l c o n t a m i n a t i o n .
C a us e o f c o l i f o r m and s t r e p t o c o c c i a r e human s o u r c e s and u n t r e a t e d raw s e w e r a g e .
S o u r c e } Enex R e p o r t s Compiled from t l ie s t u d y o f t h e p o l l u t i o n o f
Dal L a k e , S r i n a g a r K a s h m i r ( I n d i a ) .
108
physico-chemical Characteristics of Water :
Temperature j
The Dal Lake is a shallow and warm water body, the
temperature ranges from 5 C (in winter) to 31 C (in summer)
(Table- XVIIl).
Dissolved Oxygen :
The Dal Lake body is well oxygenated and the dissolved
oxygen ranges from 19.0 mg/1 (in summer) to 7.0 mg/1 (in
winter)(Table-XVIII) ,
Transparency :
The lake waters are reasonably clear and transparency
(Sechi Disc) has the mean range value from 0.97 meter to
2.6 meters (Table-xvill).
Hydrogen-Ion Concentration :
In general the surface waters of the lake are mildly
alkaline to highly alkaline in nature. Generally, pH varies
from 7.4 to 9.5 (Table-XVIII).
109
Electrical Conductivity j
Electrical conductivity is a measure of the mineraliza
tion and is indicative of the salinity of the surface waters.
The lake waters have low specific conductivity with an average
value of 136 micromhos/cm at 25 C (Table-XVIIl) .
Alkalinity (as CaCO^) t
The Dal Lake waters are moderate to hard in alkalinity
which ranges from 30 mg/1 to 140 mg/1 (Table-XVIII).
Solids :
The Lake waters are generally low in solids. The solids
are high near Telbal Nallah and the Dal Gate. The total solids
present in one litre of lake water is 100 mg (mean) of which
dissolved and suspended constitute 93 and 7 mg/1 respectively
(Table-XVIII).
Major Metals s
Calcium J
It is most common constituent present in the lake waters
110
The data presented in Table-XV reveals that the concentration
of Ca in the lake waters range from 3.43 to 44,06 ppm. The
average value of Ca is 25.76 ppm. The highest (44.06) concen
tration was recorded near Oberoi Palace Hotel (sample no. 1)
and loweat (3.43) near Kush Mohalla Telbal (sample no. IG).
Further, the Table-xvirepresents that the Floating Garden Area
contain maximum content of calcium of the order of 24,91 ppm,
whereas it is lowest in the Bod Dal sub-basin (18,30 ppm).
Magnesium :
Magnesium is responsible for the hardness of water and
low concentrations are not harmful. Table-XV reveals magnesium
range in the lake waters from 2.62 to 28.01 ppm. The lowest
value (2,62 ppm) of magnesium has been recorded near Dugpora
Telbal (sample no. 17) and highest value (28.01 ppm) near the
Nowpora bridge (sample no. 21). The average value of magnesium
is 8.12 ppm. Table-XVIalso reveal that the Hazratbal basin and
Bod Dal have almost identical values for magnesium of the order
of 5 ppm, whereas Lokut Dal and Floating Garden Area possess
average magnesium content 6.97 and 9,21 ppm respectively.
Ill
Sodium 3
The sodium value in the lake waters range from 0,06 to 3,60
ppm (Table-XV). The lowest values were recorded in the samples
taken near Cheshma^aHL, Nishat Mohalla and Nagin bridge (sample
nos. 4, 11/ 19). The highest values was recorded near Rupa Lank
(sample no. 28). The average Na value for the lake water Is G.44
ppm. Hazratbal basin. Bod Dal, Lokut Dal and Floating Garden Area
have average sodium concentration 0.21, 0.75, 0,29 and 0,42 ppm
respectively (Table-XVI).
Potassium
The average value of potassium in the lake waters is recorded
as 0,28 ppm. The potassium values range from 0,02 to 1.50 ppm. The
sample from Nowpora (sample no. 21) represent the highest potassium
content (1,23 ppm). The average potassium content for the four sub-
basins of lake is 0,16, 0.76, 0.29 and 0.42 ppm respectively
(Table-XVI).
Table-XVII shows seasonal variation in case of Ca and Mg at
four stations of the sub-basins, whereas little or no variation
exist in case of Na and K. Ca and Mg at four stations of the sub-
basin waters are high during autumn than in summer. The findings
are in compatible with the work of Agarwal (1981).
On the basis of present investigation the ionic composition
of the Dal Lake water for cations could be arranged as C3'*"^^Mg^^ + s +
. Na ^ K . Further, the observation made on the four major metals
is in agreement with the observation made by Zutshi et al. (1978)
and Agarwal (1981).
117
Carbonate j
The carbonates are absent in water samples at Rupa Lank
and Nehru Park stations whereas it was recorded 7 ppm (9 ppm
in autumn) and 9 ppm (12 ppm in autumn) at Sona Lank and
Karapura pain stations respectively (Table-XVII) .
Bicarbonate ;
Maximum content of bicarbonate ions is recorded at
station Karapura pain which is of the order of 167.50 ppm
(189,10 ppm in autumn) whereas Nehru park records 85 ppm
(122 ppm in autumn) which is lowest during summer at this
station. During summer bicarbonates have been recorded at
Sona Lank and Rupa Lank of the order of 125.37 ppm and 95.31
ppm respectively (Table-XVII).
Sulphate :
Station Karapura pain records 172.81 ppm (195.87 ppm
in autumn) of sulphate content which is the highest and at
Nehru park station the value recorded is 105.31 ppm (136.61
ppm in autumn) which is the lowest; Sona Lank and Rupa Lank
recorded 145.35 and 121.43 ppm respectively during summer
(higher values observed during autumn)(Table-XVII).
113
Chloride :
The value of chloride at the four stations of the sub-
basins range from 37.05 ppm to 72.21 ppm. It is lowest at
Nehru park (37.05 ppm), and highest at Karapura pain station
(72.21 ppm), whereas the concentration is almost uniform for
the Sona Lank and Rupa Lank stations (Table- XVII).
The values determined for chlorides are higher than
reported in Enex (1978). The enhancement in the chloride
content is ascribed to the increase in the raw sewage over
the years. Sulphate content recorded has been higher than
the chloride content whereas reciprocal has been reported by
Zutshi and Vass (1978). Table-XVII also indicates seasonal
variation in case of carbonates, bicarbonates, chlorides and
sulphates. Autumn season indicates high concentration in case
of anions.
On the basis of present investigation the ionic compo
sition of the Dal Lake water in case of anions could be
arranged as S0~ "^ HC0~'^C1''.
Trace Metals s
Apart from useful functions, although in very small
amount, trace metals play a very important role in the chemical
114
reactions in an aquatic environment and for the healthy growth
of plants. These are known as minor or trace metals.
Trace metals like Sr, Pb, Co, Zn, Cu, Mn, Fe, Ni, and
Hg were determined in the samples of lake waters. Further,
the metals namely sr, Pb, Co, Zn, Cu, Mn, Fe, Ni, Rb, Cd,
Cr, Li and Ba were determined in the samples at the four
stations of sub-basins. The results of chemical analysis ore
given in Tables-XV & XVII.
Strontium :
The strontium concentration ranges from 0,01 to 0,12
ppm, and the average value for the lake waters is 0.034 ppm.
Sada Kadal and Nowpora bridges (sample nos. 2 0 and 21), are
the two localities which represent the highest value that is
0.12 ppm (Table- XV).
However, Table-xvi indicates average strontium values
0.04, 0,03, 0.02, 0.05 ppm in Hazratbal basin. Bod Dal, Lokut
Dal and Floating Garden Area respectively.
Lead J
The lead concentration in the lake waters range from
0.03 to 0.42 ppm. The average lead concentration is 0.122 ppm
115
whereas the highest value was recorded mid of Nehru park anri
Dal Gate area (sample no. 23) which is 0.42 ppm. In some of
the water samples the lead was not detectable (Table- XV).
Table-XVI indicate average lead values 0.07, 0.06, 0.19 and
0.30 ppm in the Hazratbal basin. Bod Dal, Lokut Dal and
Floating Garden Area respectively.
Cobalt :
The average value of concentration of cobalt in the
lake waters was found as 0.052 ppm.. It ranges from 0.02 to
0,10 ppm (Table-xv ). However, Table-XVI indicates almost
uniform concentration of cobalt in the three sub-basins of
the lake, namely in Hazratbal basin. Bod Dal and Floating
Garden Area.
Zinc i
The concentration of zinc in the lake waters range
from 0.02 to 0.12 ppm with an average value of 0.056 ppm. Highest
concentration of the order of 0.12 ppm is recorded near the
locality Bren (between Bren and Lam) in sample no. 8. It can
be said th^t in a few samples concentration of zinc has been
observed in the water samples in others it was found undetectable
116
(Table- XV, Table-xVI indicates average zinc values or, 0.04,
0.06, 0.04 and 0.06 ppm in the Hazratbal basin. Bod Dal,
Lokut Dal and Floating Garden Area respectively which depicts
on an average a uniform concentration of zinc.
Copper s
Most of the Lake water samples do not reveal any copper
concentration within detectable limits. In few samples, it
ranges from 0,01, to 0.04 ppm. The highest value of 0,04 ppm
has been observed near Hazratbal shrine (sample no. 35)? the
lake waters have an average copper concentration of 0.024 ppm
(Table-XV).Table-XVI reveals average concentrations in the
three sub-basins namely, Hazratbal basin. Bod Dal and Floating
Garden Area as 0,03, 0,03 and 0.01 ppm. respectively. This is
indicative of uniform concentration in the three sub-basins.
Manganese :
The manganese concentration in the lake has been detected
in a few samples only. It ranges from 0,02 to 0.31 ppm. The
average value calculated for the lake waters is 0,075 ppm.
The highest concentration is recorded near Kush Mohalla -
Telbel (sample no. 16) which is found to be 0.40 ppm (Table-XV)
117
Table-XVI indicates that the Hazratbal basin and Floating
Garden Area have Mn concentration of 0.01 and 0.07 ppm
respectively.
Iron, Nickel and Mercury :
Tables- XV indicate that these three trace metals
could not be found in the lake waters as these existed below
the detectable limits.
Rubidium, Cadmium and Chromium :
Table-vnrepresents that three metals are under one
ppm in the samples of stations at Sona Lank, Rupa Lank, Nehru
park and Karapura pain. In case of rubidium, cadmium and
chromium, it ranged from 0.02 to 0.12 ppm (higher in autumn),
0,02 to 0.05 ppm (higher in autumn), and 0.16 to 0.62 ppm
(higher in autumn) respectively.
Lithium and Barium :
Table-xVIIindicates the lithium is probably absent in
the lake waters at the four stations of sub-basins, whereas
barium ranges from 0,67 to 1.93 ppm (higher in autumn). It is
118
highest at the Nehru park and lowest at the Rupa Lank of
lake sub-basins.
Phosphorus s
In water, phosphorus is usually present as phosphate,
polyphosphate and organically-bound phosphorus. The total and
available phosphorus is reported generally low in the lake
waters. Total phosphorus ranges from 0,031 to 0,18 mg/1 whereas
available phosphorus ranges from 0,001 to 0.075 mg/1 (Table-Xvni)
Nitrogen :
Nitrogen may be present in water as ammonia* nitrite,
nitrate and organically bound nitrogen. The concentration of
ammoniacal nitrogen levels in Dal Lake water ranges from 0.005
to 1.0 mg/1; nitrite nitrogen levels in Lake waters are between
trace concentrations and 0.02 mg/1; and nitrate nitrogen range
from trace concentrations to 0.08 mg/1 in the lake waters
(Table- XVIII).
Data presented in Table-XV reveal that the trace metals
are either undetectable or are under 1 ppm. The metals which
are undetectable are Fe, Ni and Hg. Mn, Cu and Zn, are either
undetectable or extremely in low concentrations and have been
119
detected in a few Samples only. Agarwal (1981) reports that
Fe, Mn, Cu and Zn were undetectable in surface water samples.
However, incidence of these metals in the results may be
ascribed to the weathering effects upon rocks, sedimentation
in lake body, and anthropogenic impact over the years.
Data presented in Table-XVH for four stations namely,
Sona Lank, Rupa Lank, Nehru Park and Karapura Pain (of Floating
Garden Area), reveal that Ca, Mg, CO,* HCO^* CI, SO- and trace
metals depict seasonal variation in their concentration, less
concentration in summer than in autumn. Na and K do not depict
major seasonal variation in their concentrations. Sr, Pb, Co,
Zn, Rb, Cd and Cr are under one ppm during both the seasons
at the four stations. Mn and Cu either undetectable or under
one ppm. Fe and Ni undetectable. Li was not detected. Ba is
under one ppm in summer and near or above one ppm during
autumn. The correlation of summer with autumn metal concen
trations in lake waters of sub-basins at four sample stations,
reveals that the concentration in general during autumn is
higher than during summer. The low concentrations in lake
waters during summer is due to the adequate influx of snowmelt
waters in the lake and probably occurrence of evening rains
during summer season over the lake body.
120
Water Quality Criteria In relation to Its Use s
The term 'quality' as applied to water embraces the
combined physical, chemical and bacteriologlcal-cum-blological
characteristics and is a dominant factor in determining the
adequacy of any supply to satisfy the requirements of various
water uses. The interpretation of a chemical analysis Is
highly subjective matter and is not possible to have a single
criteria that can have universal application. A certain
accepted standard is, therefore, adopted while doing the
interpretation of chemical results of water in relation to
its use. The main classes of uses are : domestic, agriculture
and industrial.
Water Quality For Domestic Uses s
Various organisations all over the world viz., USPHs
(1962), Water Resource Coirunission, Canada (1968), -Indian
Council of Medical Research (1975), USEPA (1976) and World
Health Organization (1984-1985) have laid down certain guide
lines for evaluation of water quality for domestic supplies.
The primary aim of these guidelines is the protection of
public health and well being of mankind.
121
Tables-XV, XVII show the background levels of major
and trace metals In the waters of Dal Lake. These tables
Indicate that by and large the metal ion concentration except
Sr, Pb, Mn, Cd and Cr are within the permissible limits
recommended by the World Health Organisation, for drinking
water, Infact, it was only in a few samples that the metal
concentration of Sr and Mn was found beyond the permissible
limits, whereas all the samples contain Pb, Cd, and Cr beyond
the permissible limits set by World Health Organis?ition(w.H,0.).
The W.H.O. maximum permissible limits for Pb, Mn, Cd, and Cr is
0.05, 0,1, 0.005, and 0,05 ppm respectively. It has been reported
(Enex, 1978) that the lake waters are moderate to hard, contain
ing moderate concentrations of carbonate, bicarbonate and hydro
xide ions. The concentration of metals detected in thp surface
waters of the lake have been compared with the work of Koul
and Zutshi (1987). This correlation revealed metal enrlchmf^nt
in lake waters over the years.
Table-xVIH contains physico-chemical and bacteriological
characteristics of the lake waters, pH, total solids, alkalinity
are within the permissible limits of W.H.O. (1984). The total
coliform bacteria range from 640 to 2,400 MPM/100 ml for the
four sub-basins of the lake, and total faceal streptococci
range from 0 to 2,400"*" MPN/100 ml for the sub-basins of the
122
lake. Zutshi (1987) reports at some places the total collform
count exceeds 2,400 (MPN/IOQ ml) which clearly Is nn indicntion
of bad water* The total collform bacteria seem withii the permi
ssible limit. The coliform MPN should be less than 5000/100 ml.
(Dasgupta, 1980-81).
Environmental Significance of Major and Trace Metals in Lake Waters «
The average concentration of metals in the lake waters
have been represented by the histograms (Figs. 17, 18, 19 & 20)
In the decreasing order of their concentrations, the metals
in the lake waters are Ca, Mg, Na and K? and Pb, Mn, Zn, Co,
Sr and Cu. Further, the average concentrations of trace metals
and anions recorded at the four sampling stations in the lake
basins (during summer season) in order of their decreasing
concentrations are Ba, Cr, Rb and Cd; and SO., HCO^, CI and
CO3.
Depending upon physical parameters and physico-chemical
environment of the lake body and its waters the fate and
chemical behaviour of the metals in the lake waters is not
fully understood and worked out, however, it can be said that
some metals remain in the soluble state, some are precipitated
as insolubles and some are taken up by the plants for their
growth.
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125
Table - XV show the background levels of major
and trace metals in the lake waters of DaL Lake. The lake
waters have as expected high calcium and low magnesium
content. Mg/Ca ratios were in general found to be in the
range of 1 s 3. This ratio is compatible with the findings
of Zutshi and Vass (1978). However, Agarwal (1981) reports
Mg/Ca ratios to be in the range of 1 : 4. It is well known
that Mg/Ca ratios in the water appears to control the carbonate
phase precipitated in a lake, and most fresh water lakes have
Mg/Ca molar ratios well below 3.
It may thus be inferred that for Dal Lake the Mg/Ca
ratios point to the presence of calcite in sediments of the
lake. The following generalized empirical relationships have
been proposed by Muller et al. (1972) on the basis of Mg/C^
ratios.
Mg/Ca Primary precipitate Sediment
< 2 Calcite Calcite
2-12 Mg-Calcite Dolomite Aragonite
> 12 Aragonite Aragonite
126
Zutshi and Vass (1978) reported formation of marl on
leaves and stems of macrophytes in the Dal Lake and according
to Wetzel (1975), in hard water lakes, calcium carbonate
precipitation can function not only as a scavanger of some
inorganic nutrients by co-precipitation but also act as a
a removal agent of dissolved organic matter by adsorption.
This might be one of the reasons for low plankton population.
The incidence of low Na and K in lake waters could be ascribed
to relatively low derivation of these cations from the catchment
,lithology and probable uptake of K by plants. CO^. CI and SO.
can precipitate within the lacustrine environment. HCO- ion is
probably derived from lithounits.
In general/ it can be said that the oxidising environment
favours the trace metals to combine with the oxygen thus forming In lake
oxides and hydroxides./Sr remains in the diluted state. Local
precipitation of sulphides is a possible control mechanism for
five of the metals Pb, Zn, Cu, Hg and Cd, but is probably not
the chief controlling factor because of the shallow nature of
the lake body. Adsorption is a possible mechanism for all metals
except Co, Ni and Cr, if Cr is assumed to be removed by local
reduction and precipitation of the hydroxide, and the other
two metals by organic reactions, the existing concentrations
can be fairly accounted for. Fe was not detected in lake waters
probably because of its affinity for oxygen to attain molecular
127
stability or precipitate as oxide or hydroxide in the lake
environment, Ni and Hg were also found at undetectable levels.
Elemental mercury has a low solubility and the levels in surface
water will probably be highly insignificant irrespective of the
mercury input. Zn and Cu can combine with the sulphates thus
producing Zn and Cu sulphates. The fate of Rb and Cr remain
unobvious and probably remain in the diluted state, because
they are highly in trace concentrations. Lithium was not
detectable at the four sampling stations of the Dal Lake, as
the metal is typically related to mineral weathering and is
not derived from fertilizers, show no significant relation to
landuse.
The phosphorus concentration in lake waters (Table-XVIII)
is very low as compared to very high concentration in lake
sediments (Agarwal, 1981). The distribution of phosphate
between sediments and overlying water is of considerable
Importance for the productivity of the lake.
In the presence of oxygen, a considerable part of
ammonia so formed is nitrified, apparently in two stages,
firstly to nitrite and then to nitrate. All these forms act
as plant nutrients. The low levels may be due to two factors
which together are known to remove phosphorus from water and
bind it up in the sediment. One of these is the suspended
128
solids which occur in the water. Sorption of phosphorus by
this particulate matter reduces soluble concentrations and the
subsequent settling and deposition of this particulate material
will reduce the total quantity of phosphorus in the water mass.
Soluble phosphate ions may also combine chemically with metallic
Cations to form precipitates. Precipitation of calcium carbonate
(marl) is accompanied by phosphorus precipitation as calcium
phosphate. As Dal Lake waters are medium to rich in calcium,
some phosphate is considered to be precipitated as calcium
phosphate and bound up In the sediments (Enex, 1978),
It is added that N, P, K, Ca, Fe and Mg and Mn, Zn, Cu,
and Co are the major and trace metals probably required by the
plants particularly by algae for their growth in the Dal Lake
environment/ that may be the reason that N, P, K, Fe, Mg, Zn,
Cu and Co are found in low concentrations in lake waters.
Perusal of Table-XV supported by isocon diagrams
(Fig. 21 St 22 ) indicates that in general the peripheral part
of the lake waters including southwest waters of the lake have
high Ca and Mg contents compared to central parts of open
waters of Hazratbal basin. Bod Dal and Lokut Dal. The reason
being, that the peripheral parts are the iimiediate recipients
of these metals from human and natural sources. Regarding Na
it can be stated that no systematic zonation is established
except in a few water samples of the southwest area and Bod Dal
129
4- Mg
4.N Na iN
K
r m < 0,2b
EIDo.25-0 60
• I >O.SC
Km! 1/2 0 IKr
FIG.21 DISTRIBUTION OF Ca,Mg,Na,&K IN WATERS OF DAL LAKE
1 3 0
Sr I N I N
Pb
PPm r m < 0.05
0.05-0.10
I )0.10-0.15
• • > 0.15
Co
PPm
rm <o.o3 0,03-0.06
I I 0.06-0.09
• i >0.09
Ktnl 1/2 0 IKm
FIG. 22 DISTRIBUTION OF Sr ,Pb ,Co & Zn IN WATERS OF DAL LAKE
131
of the lake which contain high concentration of this
metal, where the concentration is found high that may be due
to local evaporation in that zone. Western, southwestern of
the lake waters have high K concentration, however, a few
samples from central part of Bod Dal and Lokut Dal also contain
appreciable concentration of K. Probably either K is not
consumed by plants or vegetation is not abundant, western
and southwestern area hold Floating Gardens, therefore,
release K from agricultural practices. Na and K is high in
Nowpora canal (underneath bridge, sample no. 21), whereas
Telbal Nallah also carries a high concentration of Ca and Mg.
In Nowpora Canal the waters remain stagnant, probably showing
high concentrations of these metals Na and K. Sr concentration
is high in west and middle and low in the northeast, east and
southwest of the Dal Lake. High in west is due to release of
detergents alongwith domestic waste. Pb is low in the central
parts of these basins namely, Hazratbal basin. Bod Dal and
Lokut Dal, whereas a few samples from Floating Garden Area,
Hazratbal basin and near the human settlements, it is still
having more concentration in water samples. It is still higher
in a few samples of Lokut Dal and Floating Garden Area but in
general very low around the peripheries. Co Is seen to decrease
towards central parts of Hazratbal basin. Bod Dal and Lokut Dal,
however, southwest of the lake body including Floating Garden
Area and sample no. 2 have fairly a high concentration of cobalt.
132
The reason of being less in Pb and Co concentration towards
the central parts of sub-basin is because of immobility of
two metals to move towards central parts of the basins. Samples
from western Dal revealed zinc not in detectable limits whereas
east of Dal (including drainage samples), south and southwestern
samples contain zinc probably derived in low concentrations
from natural sources despite its restricted mobility. There is
a tendency to increase Zn towards the central parts of Bod Dal
and Lokut Dal. Cu and Mn were not detectable in most of the
samples, whereas samples from southwestern portion of the lake
body again showed zinc concentrations probably derived from
domestic detergents and fur dressing.
Variations in average concentration of metals in waters
of Dal Lake sub-basins are shown in Table-XVI, Fig. 23,24 & 25.
This reveals trough in Bod Dal in case of Ca as the sub-basin
is little affected by the domestic effluents; increasing trend
in case of Mg increase in case of Floating Garden Area because
of proximity to population clusters; Na and K depict peak in
Bod Dal and trough in Lokut Dal. Peaks are because of dispersion
of these metals into Bod Dal from Floating Garden Area and
subsequent evaporation of Na; Sr show a trough, Pb follows
increasing trend; Co shows peak in Lokut Dal, Zn do not depict
a prominent peak and trough; Cu shows only decreasing trend
indicating natural source; Mn shows a trough, probably having
1
1 3
V
^i 1 v
:: o w - «i a >»
t \ < 1 -J o u.
-J
u
• p
1 3 3
t r. a. u\ <3 m
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O
-(uj<.(l)r(OUVal(l33llOL) 1 O
>- o i"i l o t c. . , .1
o
134
no impact of Mn from anthropogenic sources on Dod Dal and
Lokut Dal. Hence, it can be stated that in the Floating
Garden Area Ca, Mg, Sr, Pb, Mn and Zn are increased because
of anthropogenic impact whereas Cu gets decreased explaining
probably natural source of this metal; Na and K is maximum in
the Bod Dal probably because of evaporation of Na whereas Co
is maximum in the Lokut Dal probably because of domestic
detergent effluent from the house boats.
Variation in average concentrations of anions and trace
metals at four stations of Dal Lake sub-basins (during summer)
are shown in Table-xvn Fig.26,27. This indicates enhancement in
concentration of Rb and Cd at Karapura Pain station because of
anthropogenic impact, Cr follows uniformally an increasing
trend, Ba shows peak at Nehru Park station because of human
impact from house boat population. C0~, HCO, and SO. depict
troughs at Nehru Park station whereas they are high at the
Karapura Pain station, HCO^ and SO. are due to agriculture
practices upon the Floating Garden whereas CO^ associated with
natural drainage entering into the Karapura Pain area, increase
in trend of CI ^t Karapura Pain is because of the raw sewage.
It is apparent from the distributional pattern of the
graphical plots and isocon diagrams that the western and south
western part of the lake body including Floating Garden area
will emerge a potential zone of Inorganic pollutants in the
135
S gz a a. <
a
_ o a I
2 3
3 b i t i/> vs r4
( ^ d d ) NOllvyiN3DNO0
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136
lake water surface in near future. This enhancement is
because of the fact, thnt the sub-basin that is Floating
Garden Area is getting isolated from the open water areas,
because of human encroachments and developmental activities.
SEDIMENT CHEMISTRY J
For evaluating the hydrogeochemistry of the Dal Lake
sediments, about thirty six surficial sediments of the Dal
Lake basin were collected from a variety of environmental
and geographical locations. During sampling only 36 sediment
samples could be collected from the fifty locations where the
water samples were collected (Fig. 28 )(Table- XIX ). As
mentioned earlier the Dal Lake is a shallow lake with differing
compositional characteristics of the sediments. Sediments of
the lacustrine environment generally are the accumulator for
various metals received from the natural and man induced
processes. Hence it is well known that major and trace metal
contents of waters and sediments are normally controlled by
the abundance of metals in rock and soil of the catchment area
and by their geochemical mobility. The catchm<= nt area containing
mineralized rocks will usually have elevated metal levels
(Abdullah et al., 1972 and Jackson, 1978). Human activity also
contributes to the enhanced metal levels in lakes.
1 37
FIG.28 MAP SHOWING SEDIMENT SAMPLE LOCATIONS
IN DAL LAKE BASIN
1 3 8
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140
The major and trace metals detected in the surficial
sediments of the Dal Lake basin include Ca, Mg, Na, K, Sr,
Pb, Co, Zn, Cu, Mn, Fe, Ni/ Rb, Cd, Cr, Li and Ba. Besides,
pH of the bottom sediments was also investigated. Data on
nutrients viz., phosphorus and nitrogen have been adopted
from the earlier workers (Enex, 1978).
The analytical results of sediments are shown* in Table-
XX., The mean metal values in the sediments of sub-basins of the
Dal Lake are shown in Table- XXI. The analytical results are
thus discussed below in detail.
Physico-chemical Characteristics of Sediments :
pH :
The pH of each sample of the surficial sediments was
measured. The pH ranged from 7.1 - 8.8, the average for the
Dal Lake sediment is 7.5 (Table- XX ). However, Table-XXI
indicates average pH value 9.33, 7.33, 7.65 and 7.41 for
the Hazratbal basin (which has the highest), B9d Dal (which
has the lowest), Lokut Dal, and Floating Garden Area respec
tively. Hazratbal basin shows more alkaline tendency.
141
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142
1
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143
Sediment Texture :
The Various size fractions which compose the
bottom sediments of the various sub-basins of the lake body
are that the peripheral zone (or near shore) contain sandy-
silt/ central (or offshore) zones have silty clay composition,
whereas the intermediate zone of the basins have sand-silt-
clay fractions. Sand accumulation takes place at the main
input to the lake namely, Telbal nallah. The distribution of
the lake sediments clearly indicates coarse sediment along
the lake peripheries whereas the offshore (or central basins)
zone deposits are composed predominantly of fine grained
sediments (Agarwal, 1981).
Organic Carbon :
Higher organic carbon values occur for central basins
whereas low values occur in association with sands. The
organic carbon distribution parallels the grain size distri
bution for the sediments of Dal Lake with increasing values
from the coarse peripheral sediments to the finer central
basin sediments (Agarwal/ 1981).
144
Inorganic Carbon t
Carbonate minerals are conunon constitutent of lacustrine
sediments. In contrast to an oceanic environment the bulk of
primary lacustrine carbonates are inorganic chemical precipi
tates. Inorganic carbon shows a positive correlation with
clay and organic matter content. As the clay content increases
towards the basins, the inorganic carbon also increases, whereas
it decreases towards the peripheral zone. Hence it is stated
that the inorganic carbon distribution parallels the grain
size distribution of sediments (Agarwal, 1981).
Major Metals :
Calcium :
The average calcium content of the lake sediment is
about 494.2 ppm. It ranges from 242.75 to 970.30 ppm
(Table- XX ). The mean calcium content in Hazratbal basin.
Bod Dal, Lokut Dal and Floating Garden Area is recorded
622,61, 446.41, 442.12 and 676.27 ppm. It is highest for
the Floating Garden Area (Table- XXI ).
145
Magnesium s
The average magnesium content of the lake sediments
is 146.03 ppm. It ranges from 20.40 to 389,75 ppm (Table-xx).
The mean magnesium content in Hazratbal Basin, Bod Dal,
Lokut Dal and Floating Garden Area is recorded 177.86, 68.53,
233.32 and 138.75 ppm respectively. It is highest for the
Lokut Dal while lowest for the Bod Dal (Table-xxi).
Sodium s
The average sodium content of the lake sediments is
75.43 ppm. It ranges from 13.20 to 138.95 ppm (Table-XX).
The mean sodium content in Hazratbal Basin, Bod Dal, Lokut
Dal and Floating Garden Area is recorded as 60.54, 76,9 3,
76,09 and 83.04 ppm respectively, it is highest in case of
Floating Garden Area and lowest for the Hazratbal basin
(Table-XXl).
Potassium :
The average potassium content of the lake sediments is
57,75 ppm. It ranges from 8.90 - 99.72 ppm (Table-XX).
The mean potassium content in Hazratbal basin. Bod Dal,
146
Lokut Dal, and Floating Garden Area is recorded 50.00,
66.71, 35.95 and 58,04 ppm respectively. It is highest
in case of Bod Dal (66.71) and ; owest in case of Lokut
Dal (35.95) (Table-xXl).
The Dal Lake sub-basins do not depict any great
variation with regard to sodium and potassium.
Trace Metals s
Strontium :
The strontium concentrat ion range from 3.20 to 18,20
ppm, and the average value for the lake sediments i s 7.89
ppm. The lowest value i s recorded at Aabi-Karapur (Rainawari
sample no. 42) and highest value i s recorded around Sona Lank
area (sample no. 33) (Table- XX).
However, Table-XXI ind ica te mean strontium values 11,85,
7 .7 , 9,35 and 5,82 ppm in Hazratbal basin. Bod Dal, Lokut Dal
and Float ing Garden area r e s p e c t i v e l y .
Lead s
The lead concentration in lake sediments range from
0.267 to 1.115 ppm. The average content of lead is 0.642 ppm.
147
The lowest value is recorded Mid of Oberoi Palace and Centaur
Hotel (sanple no, 2) and highest value is recorded for Zoji
Lankar brdige (sample no. 40) (Table-XX),
However, Table-XXI indicates mean lead values 0.64, 0.66,
0,47 and 0,69 ppm in Hazratbal basin. Bod Dal, Lokut Dal and
Floating Garden Area respectively.
Cobalt t
The average concentration of cobalt in lake sediments
was found as 0,31 ppm. It ranges from 0.17 - 0,38 ppm
(Table-XX), However, Table-XXI indicates almost uniform
concentration of cobalt in the four sub-basins of the lake.
Zinc t
The concentration of zinc in lake sediments range from
0,649 - 13,00 ppm with an average value of 3.65 ppm. Highest
zinc concentration of the order of 13.00 ppm is recorded in
the sample no. 41 (Zoji-Lanker Panditpura) (Table-XX).
However, Table-XXI indicates mean zinc value 0.84, 2.33,
3,47 and 7,53 ppm in the Hazratbal basin. Bod Dal, Lokut
Dal and Floating Garden Area respectively.
148
Copper :
The concentretion of copper in the lake sediments range
from 0,24 to 4.40 ppm with an average value of 0.90 ppm.
Highest copper concentration of the order of 4.40 ppm is
recorded in the sample no. 39 (Hasanabad - Rainawari near
Naidyar bridge) (Table- XX ). Table-XXI reveals mean
concentrations in the four sub-basins nanvely, Hazratbal
basin. Bod Dal, Lokut Dal and Floating Garden Are?i recorded
at 0.46, 0.71, 0,48 and 1.71 ppm respectively.
Manganese :
The average manganese content in the lake sediments is
recorded as 4.42 ppm, and it ranges from 1.38 - 6.98 ppm.
The highest value is observed in the sample no. 17 (Dugpura-
Telbal)(Table- XX ). Table-XXI reveal mean manganese concen
tration in the four sub-basins Hazratbal basin. Bod Dal, Lokut
Dal and Floating Garden Area recorded at 4.10, 3.39, 3.36 and
4.60 ppm respectively. No substantial variation is observed in
the mean values of manganese for the four sub-basins of the
Dal Lake.
149
Iron t
The average iron concentration in the lake sediments
is recorded as 186.64 ppm; ranging from 89,60 to 266.90 ppm
in the sediment samples. Highest value which is of the order
of 266.90 ppm is recorded in the sample no. 32 (Hazratbal
basin (Table-XX).
Table-XXI indicates the mean value of iron in the
Hazratbal basin. Bod Dal, Lokut Dal and Floating Garden Aren
as 176.75, 170.60, 172.00 and 212.81 ppm.
Nickel 2
The average nickel concentration in the lake sediments
is recorded as 0,72 ppm; ranging from 0.46 - 0,91 ppm in the
sediment samples. Highest value which is of the order of 0.91
ppm is recorded in the sample no. 14 (Shalimar Mohalla)(Table-xx)
However, Table-xxi indicates the mean value of nickel in the
Hazratbal basin. Bod Dal, Lokut Dal, and Floating Garden Area
as 0.68, 1.17, 0,73 and 0.73 ppm respectively.
Iron and nickel do not show any great variation in the
mean values of the four sub-basins of the Dal Lake.
150
Rubxdium :
The average rubidium content in the lake sediments is
recorded 0.74 ppm, and it ranges from 0.31 - 1.10 ppm. The
highest value is observed in the sample no. 14 (Shalimar
Mohalla)(Table-XX ). Table-XXI reveals mean rubidium concen
tration in the four sub-basins Hazratbal basin. Bod Dal,
Lokut Dal and Floating Garden Area recorded as 0,57, 0.75,
0,67 and 0.88 ppm respectively. Very little variation exists
in the mean rubidium values of the sub-basins.
Cadmium s
The average cadmium conten t in the lake sediments i s
recorded 0.05 ppm, and i t ranges from 0,03 - 0.08 ppm. The
h ighes t values i s observed in the sample no. 33 (Sona Lank)
(Table-XX ) • Table-XXI revea l s mean cadmium concen t r a t i on
in the four sub-bas ins Hazratbal b a s i n . Bod Dal, Lokut Dal
and Float ing Garden Area recorded as 0.06, 0 .05, 0.04 and
0.05 ppm r e s p e c t i v e l y . Very l i t t l e v a r i a t i o n e x i s t s in the
mean cadmium values of the s u b - b a s i n s .
151
Chromium t
The average chromium content in the lake sediments is
recorded 1,62 ppm, and it ranges from 0.94 - 3.76 ppm. The
highest value is observed in the sample no. 5 (Naupura-near
mosque)(Table- XX ). Table- XXI reveals mean chromium concen-
tations in the four sub-basins namely, Hazratbal basin. Bod
Dal, Lokut Dal and Floating Garden Area recorded as 1.33, 1.56,
2.24 and 1.64 ppm respectively. No major variation exists in
the mean value of sub-basins.
Lithium :
The average lithium content in the lake sediments is
recorded 0.02 ppm, and lithium ranges from 0.00 - 0.05 ppm.
It varies between vary narrow limits (Table-XX ), Table-XXI
reveals mean chromium concentration in the four sub-basins
Hazratbal basin. Bod Dal, Lokut Dal and Floating Garden Area
as 0.02, 0.03, 0.02 and 0.03 ppm. The mean lithium values are
almost uniform for the four sub-basins.
Barium t
The average barium content in the lake sediments i s
recorded 0.042 ppm, and i t ranges from 0,18 - 0.98 ppm. The
152
highest value is observed in the sample no. 4 (Cheshmnr?hnhi)
(Table- XX ). Table-XXI reveals mean Barium concentrations in
the four sub-rbasins. Hazratbal Basin, Bod Dal, Lokut Dal and
Floating Garden Area as 0,48, 0.42, 0.53 and 0.26 ppm. No
major variation exists in the mean Barium values of the sub-
basins .
Phosphorus and Nitrogen s
Phosphorus and nitrogen (nutrients) are available in the
lake sediments in the insoluble state. The sediments in the Dal
Lake contain a substantial amount of organic material in asso
ciation with lacustrine and marl deposits. It is reported that
the sediments contain 0.16% phosphorus and 0.33% nitrogen and
it is considered that these nutrients are mainly located in
the upper 20 cm of the sediment. Estimates put the quantities
of phosphorus and nitrogen in this volume of sediment at 3,744
tonnes and 7,722 tonnes respectively. About 5,5 tonnes of
phosphorus and 88,9 tonnes of nitrogen are accumulated annually
into the lake body. This represents d substantial reservoir of
nutrients that are potentially available to plants in the lake
(Enex, 1978).
Tables-XX & XXI show the background levels of major and
trace metals in the surficial sediments of the lake basin and
153
sub-basins of the Dal Lake. Data presented In Table-XX
reveals that the concentration of calcium is higher than
magnesium. The lake sediments contain an abundance of calcium,
iron and magnesium. In case of calcium and magnesium the values
are above 242 and 20 ppm respectively. Most of the sediment
samples show closeness in values in case of sodium and potassium.
The values of these metals are above 8 and 2 ppm respectively.
Strontium values are above 3 ppm. Lead values are below 1.5
ppm whereas cobalt is below 1 ppm; both of t>iem do not depict
any wide range. Zinc concentration recorded in the sediment
samples is above 0.6 ppm but decipher a wide range in values.
Copper values are above 0,24 ppm whereas manganese values are
above 1 ppm. These too do not depict any wide range in their
dispersal pattern. The lake sediments contain an abundance of
iron and values recorded in the samples start almost nearly
from 90 ppm. Nickel, cadmium and lithium values do not depict
any wide range in values and their values are under 1 ppm. The
rubidium values are above 0.31 ppm, whereas chromium values
are above 0.9 ppm and depict a wide range. The Barium values
are below one ppm with a wide range.
Average metal concentration in surflcial lake sedim^ntn
of Dal lake sub-basins have been presented in Table- XXI
(computed from Table-XX ). Table-XX reveals elevated metal
levels of calcium, magnesium, iron, sodium, and potassium.
154
The average strontium concentration is above 5 ppm and the
average manganese below 5 ppm in the sub-basins of the Dal
Lake body. Average zinc values show wide variation in the
lake sub-basins whereas nickel shows almost a uniform concen
tration in the lake sediment and are around 1 ppm (+ 1 ppm).
Concentrations of seven metals viz., lead, cobalt, copper,
rubidium, cadmium, lithium, and barium are below 1 ppm
whereas Cr is above 1 ppm in the sub-basins of the Dal Lake.
Environmental Significance of major and trace metals in Xake Sediments :
The average concentration of metals in the ]ake
sediments have been represented by the histograms(Fig.29,50,31 ,32
Ca/ Fe, Mg, Na and K have been recorded in appreciable concen-
tation in the lake sediments. Sr, Mn, Zn and Cr rank second
in order of their concentration, whereas Cu, Rb, Ni, Pb, Ba,
Co, Cd and Li are in insignificant levels in the lake sediments.
Kango (1987) reported lake sediments are rich in Fe. Agarwal
(1981) reports Ca and Fe in appreciable concentrations, whereas
P and N are higher in sediment phase than in water column.
The lake sediments act as a reservoir of the metals.
The factors which influence the behaviour and accumulation
of the metals within the sediments of the lacustrine environment
155
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157
are pH, Eh, depth, temperature, photosynthesis, sediment
texture (gr<ilri nJze), orgnnic mntter, cnrbon rnntPnt (org.Trjlr of
and inorganic), metal oxides and precipitation/metals, etc.
Adsorption and complexing are processes for mobilizing or
immobilizing metals in the lake sediments. Another process
is the precipitation of insoluble snlts, for example phosphates,
sulphates, and carbonates. Tvie concentration of metals in an
acidic environment is lesser than in the alkaline environment.
The mobility of metals in an acid sediment environment with a
pH of 4 is about twice that of a neutral sediment (pH « 7) and
that mobility of metals in a sandy soil containing no clay is
about 10 per cent greater than a clayey sediment.
The lake sediments are rich in Ca and Mg contents. This
may be due to the precipitation and sedimentation of these
metals within the lake body. Fe may form metal oxide coating
around the sediment particles. These may grow by precipitation
of iron hydroxide from saturated suspension in the lake. During
this process, metal ions adsorbed on the surface of metal cxlde
particles are immobilized. Kango (1987) proposes interaction
of humic acids with various metals to form stable complex of
Pe chelates. Occurrence of increased contents of Fe and Mn in
bottom sediments against background of extremely low content
in the lake water has been reported in lake Baikal (Granina,
1987). Agarwal (1981) reports abundance of Fe in the DaL Lake
158
because of the decay of plants during the winters and subse
quent incorporation in the lake sediments. Kango et al. (1987)
reports co-precipitation of Cu and Pb with hydrous oxides of
Fe and Mn. Agarwal (1981) reports that the insoluble nutrients
(P and N) are bound up in the sediments. The most striking
feature of phosphorus is its immobility due to strong adsorp
tion of finely divided mineral soil particles. There may fee
chemlsorptlon Of phosphate accompanied by heterogeneous
formation of nuclei like formation of Ca or FePO.. Enex (1978) 4
also reports that the progressive depletion results in the
release into overlying water of nutrients previously locked
up in the sediments.
In general, it can be stated that in the lacustrin*'
environment, the major metals viz., Ca, Mg, Na and K get
associated with other ions and form complexes. Such as Cpt,
Mg and Na combine with CO^/ SO. and HCO- and make CaCO^,
MgC03, CaSO^, NaSO^ and CaHCO^ combinations. Barium can also
be bound up with the sulphates. The chief insoluble compounds
with regard to metals titat may exist In th<» lacustrine environ
ment are ZnCO^* CuCO^r PbCO^, Cd(OH), Cl, N K O H ) , / COCO»,
Co(0H)3, HgO, CaCrO^, MgCO^HjO, CaCO^, SrCO^* BaSO^, ZnSO^
and CuSO.,
The geochemlcal cycle of element released into water by
weathering or pollution is further modified by sediment water
159
interaction which indicates that the clay# carbonate and
organic fractions in sediments strongly influence adsorption
desportion reactions (Siegel, 1974). A recent review of
'experimental work also confirms that clay minerals can
effectively attenuate the dispersion of metals and pollu
tants like toxic metals, detergents and organic dyes.
Probable Source and Derivation of Metals in the Lake Environment i
The Dal Lake is a recipient of major and trace metals
from the catchment. It receives metals from point and non-
point diffuse sources. The metals which are likely to be
introduced into the Dal Lake water body, are diverse in
nature. The lake body receives metals both probably from
natural and anthropogenic sources. Todd (1980) outlined
Various sources of anthropogenic inputs which damage the
water resource bodies.
The anthropogenic input of metals into the lake body
are from various sources. The irrigation return flows Intro
duce metals viz., Ca, Mg, Na, K, HCO^, CI, SO^, NO-, Sr and
Cr. Within the catchment compound of N, P and K are applied
as fertilizers. There is the recycling of nitrogen and phos
phorus in the lake body near Floating GanJens. In addition to
160
this, pesticides applied in the orchards, may release Hg.
As far as municipal sources are concerned solid waste disposal
produces CI, SO-, Mn and Fe besides other trace metals. Deter
gents produce elements viz., Sr, Co, Zn, Mn, Fe, Ni, Cr and
Ba. Domestic sewerage adds Ca, Mg, Na# K, CI, SO. and NO .
Textile dyeing, fur dressing and laundary produce Zn, Cu,
Ni, Cd, and Cr, As far as recreational activities are concerned,
auto and boat fuel and vehicular emission (automobile activi
ties) produce Pb, Ni and Cr, they are also released from painted
sources like house-boats and small boats.
Wedephol (1967, 1970, 1972, 1974, 1978) outlined metal
content in rock forming minerals and Todd (1980) describes tVie
major natural sources of each metal from the various rock
forming minerals. The metals introduced from natural sources
are released from the lithounits of catchment due to prolonged
physical and chemical weathering action. Major and trace metals
are introduced in the lake body in solution, suspension and
carried with the sediments. From the catchment. Basalts and
Granites introduce Ca/ Mg, Fe, Na and K, Again basic and
metamorphic rocks release Sr, Pb, Co, Zn, Cu, Nl and Cr.
Mn, Cd and Ba are likely to be released from metamorphic
and sedimentary rock units. Rb and Li are probably derived
exclusively from the catchment lithology. CO^, HCO and PO.
161
to some extent are released from the chemical weathering of
limestones.
Lake sediments show spatial variations in their metal
concentration and it is rather difficult to draw generaliza
tion in each and every metal and establish zonation within
the lake body. Perusal of Table-XX supported by isocon 35, & 36)
diagrams(Fig.33,34,/_ provides a distributional picture of
each metal in the sediments of lake body. The observation
made are that Ca is high in the western foreshore area
particularly in the sample of canals (typically represented
by a high value of 970 ppm in sample no. 36). The concentration
of Ca is also high in the southwestern area. In general the
metal concentration decreases from west to east of the lake
body. High values of Mg are observed in the canals of Floating
Garden Area (two localities show the maximum concentration
near Nowpora bridge sample no.21 and Hotel Lake isle Resort
no. 36), In this case also in general the concentration decreases
from west to east. The reason being that the western and south
west area of the lake body containing numerous canal network
is infested with human sewerage menance. High concentration of
Na is found in the southwest, in the central parts of Hazratbal
Basin, Bod Dal and Lokut Dal. High concentration of K is found
in the central parts of sub-basins. This may be due to the
162
Km 1 1/2 0 IKm
FIG.33 DISTRIBUTION OF CQ,Mg.Na& K IN SEDIMENTS
OF DAL LAKE
163
Pb
l Co
P P m
DI]<0.20
0.20-0.30
0.30-0.40
Km I 1/2 0 I K m
FIG. 3A DISTRIBUTION OF Sr. Pb . Co & Zn IN SEDIMENTS OF DAL LAKE
164
4.N Cu
4.N Ni
\TD< 0.70
> 0.70
Km1 1/2 0 'Km
FIG. 35 DISTRIBUTION OFCu.Mn.Fe & Ni IN SEDIMENTS OF DAL LAKE
4! Rb
4.N
PPm
a n <o.7o • • > 0.70
165
Cr
rm < i.so > 1.50
a.N Li i"*
Ba
UZi 0 .30-0 .6C
5.CO
Km 1 1/2 0 IKm
FIG. 36 DISTRIBUTION OFRb,Cr ,L i 8. Ba IN SEDIMENTS OF DAL LAKE
166
association of K with fine grained sediments and organic
matter. High concentration of Sr is found near Rupa Lank
and Sona Lank (sample nos. 28 and 33) and other localities,
however, the concentration increase towards the peripheries.
This represents an anomaly. Probably Sr gets thoroughly fixed
with the lake sediments confined to the peripheral zone,
become immobile to move towards the central parts. Within the
lake body no defined distribution of Pb occurs, hoN;ever, a few
samples of Floating Gardens, Hazratbal Basin and Bod Dal
contain high concentration of lead. In case of Co a clear
distribution picture emerges i.e., central parts of the sub-
basin sediments contain high concentration of this metal than
peripheral part, probably, association of Co with fine grained
sediments and organic matter. High concentration of Zn and Cu
is found in the Floating Garden Area and in samples taken in
central parts of Bod Dal and Lokut Dal. Mn is high in the west
of lake, parts of other three basins and Floating Garden Area,
because of proximity to population clusters and fairly high
to low in open water areas. In case of Fe, high concentration
is found in the Floating Garden Area samples and in a few
samples of Bod Dal, Lokut Dal and Hazratbal Basin. Northern
parts of Hazratbal basin and eastern parts of Bod Dal and
Lokut Dal are having relatively less concentration. Ni is
167
high in the central parts of sub-basins and Floating Garden
Area than in the peripheral part of the lake body. Fairly
high concentration is recorded near population clusters. Rb
almost follows the same pattern as Ni. The reason is because
of fine grained sediments and organic matter in the central
parts with which both Rb and Ni are adsorbed. Cd depicts
almost uniform concentration in lake sediment9< however,
slight decrease in concentration is observed from west to
east of the lake body. Relatively a few samples of Hazratbal
Basin and Floating Garden Area contain fairly a high concen
tration of Cd. Cr is high in floating Garden sediments, in
sanples of Bod Dal and Lokut Dal the reason being proximity
to population clusters. Li concentration in sediments is
fairly high in the central parts of lake sub-basins and near
population clusters. It is seen to decrease towards the peri
pheral part. This is because of the mobility of the metal to
move with the sediment towards the central part of the sub-
basins. In case of Ba on the general basis, a loop of low
concentration is depicted within the Dal Lake. The reason
being that the lake sediments have less concentration than
lake waters.
In general, Ca, Mg, Na, K,Pb,Co,Zn,Cu,Mn,Fe,Ni,Rb,Cr,Li & Ba
are all found in the Floating Garden Area and in the southwest
of the lake sediments (which also holds Floating Garden strip?).
168
Central parts of lake sub-basins have sediments with enhanced
metal levels in case of K, Co, Mn, Ni, Rb, and Li, whereas Sr
and Ba are low in the central part of the lake and Ba more in
lake water than in lake sediments. Fe, Li and Rb are probably
carried with the fine textured sediments from the catchment
and deposited in the central basins aa they are either undetec
table or low in the lake waters.
Variations in average concentrations of metals in sediments
of Dal Lake sub-basins are shown in Table-XXI, Figs. 37, 38, 39
and 40, This reveals a trough in case of Ca because Bod Dal and
Lokut Dal are less affected by the domestic effluents compared
to western Hazratbal Basin and Floating Garden Area; these
metals are also brought with the incoming fine textured sedi
ments and high level in the Floating Garden Area is due to
excessive anthropogenic impact. Troughs are noticed in case of
Pb and Cd in Lokut Dal, lead is very high in Floating Garden
Area as it is affected by domestic effluents. Mg, Sr, Ba and
Li depict troughs in Bod Dal and peak in Lokut Dal. Lokut Dal
seems probably more affected by effluents from the House-boats
than Bod Dal which is free from human dwellings. Na and Zn
display gradually increasing trend, the rise in graph depends
upon the quantum of anthropogenic thrust. K, Cu and Rb form
peak in Bod Dal and trough in Lokut Dal, probably these metals
are contributed from the Floating Garden Area which lies to
169
700-1
675-
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550
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100-
75-
5 0 -
25-
0 I HAZRAT BAL
BASIN
1
BOO OAL 1
LOKUT OAL 1
FL0A1IN6 GAROEN AREA
FIG-3 7 VARIATION IN AVERAGE CONCENTRATION OF C o .M g^No.K 1 F t IN SEDIMENTS OF DAL LAKE SUBBASINS.
Seal* '. I cm: 25 ppm
1 7 0
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171
172
the west of Bod Dal. Fe and Mn show gradually increasing
trend towards Floating Garden Area as these metals get
enriched in concentration in this sub-basin because of
anthropogenic impact from solid waste disposal. Fe seems
to be carried with the sediments from the catchment rocks
as this metal was not detected in the lake water. Cr displays
a minor peak in Lokut Dal, Cr is adsorbed by sediments, the
source of which is painted boats, vehicular emission and
house-boat effluents. Co follows almost a uniform pattern.
Ni shows a peak in Bod Dal. This is probably due to flow of
nickel rich domestic effluents from the Floating Garden Area
into Bod Dal, since Bod Dal is adjacent to the Floating Garden
Area.
It is apparent from these graphical plots that the
western and southwestern part of the lake body including
Floating Garden Area and central parts of lake sub-basins
will emerge a potential zone of inorganic metal pollution
in lake sediments in near future. Also most of the metal
concentration have been found high in the sediments of the
central parts of the lake sub-basins, because of the fine
texture of the lake sediments, abundance of organic matter
and mobility of certain metals to move from peripheral part
to the lake central parts. High concentration of trace
metal Rb occurring in sediments of the centre of the lake
173
sub-basins has been found in agreement with the work of
Agarwal (1981). In addition to this, high concentration of
metals have been noticed in the sediments occurring close to
human settlements.
Tables-XV & XX depict the metal concentration in the
surficial water and sediments of the Dal Lake. Table-XII
shows the tentative metal concentration assigned to the litho-
units of the catchment. On observation it was found that the
concentration of major metals (Ca, Mg, Na and K) and trace
metals (Sr, Pb, Co, Zn, Cu, Mn, Fe, Ni, Rb, Cd, Cr, Li and
Ba> in sediments is greater than in water except in case of
Co (greater in water than in sediments in Lokut Dal), Cd
(equal concentration in water of Karapura Pain and sediments
in Floating Garden Area) and Ba (higher in water samples at
four stations than in sediments in all sub-basins). Hence in
general positive correlation is established, except in case
of trace metals Co, Cd and Ba. This means higher levels are
found in the sediment phase than in the water phase. Again
comparing concentration of metals (trace and major) in
sediments with the tentative concentration levels in the
lithounits, the lithology have high metal concentrations than
in sediments except in case of Co, Ni and Cd. Low levels of
Co is in limestones, Ni in granites, and Cd in sands and clays.
Their concentration levels are low in these formations than in
lake sediments. By and large a positive correlation is, there
fore, seen. In general the metal concentration arrangement is
expressed as - lithounits sediments^^ waters.
174
Co remains in soluble state in Lokut Dal, Cd maintains
an equilibrium in sediment-water phases in Floating Garden
Area and at Karapura Pain station of the same sub-basin,
Ba is recorded high at the four sampling stations of Dal
Lake sub-basins compared to low in the sediments of Dal
Lake sub-basins; it is indicative of the fact that the barium
probably have more solubility in the lake waters and is used
by lake plants and is less precipitated. Low levels of Co
in limestones, Ni in granite, and Cd in sands and clays are
indicative of enrichment of the metals Co, Ni and Cd in
sediments from sources other than from limestones, grflnites,
sands and clays of the catchment lithounits.
175
CHAPTER - VII
CONCLUSIONS & RECOMMENDATIONS
The Dal Lake is a high altitude (1580 meters approx.
Himalayan Lake, forming a water body of Dachigam Drainage
Basin« situated on the Pleistocene alluvium, is a vestige
of major post-glacial lake. It is being reduced in dimensions
by drainage, reclamation and natural sedimentation thus attain
ing a loop shape over the past years. Catchment area of about
381*44 sq. km. accommodates Dal Lake (18.41 sq. km.) which
constitutes about 5 per cent of the total Catchment area.
The lake is multibasined consisting of Hazratbal Basin,
Bod Dal, Lokut Dal and Floating Garden Area. The maximum depth
of the lake body is 3.5 meters, the average of maximum water
depths is 2.54 meters whereas average of minimum water depths
is 1.82 meters and its bottom represents a heterogenous topo
graphy. Most of the terrain of the Catchment with moderate
and steep slopes, in general represents a precipitious topo
graphy, consisting of ridges, conical and sub-conical peaks,
hillocks, saddle-hills and spoon shaped depressions. The six
subcatchments are Dachigam subcatchment (A),Telbal subcatchment
(B),Hill-side subcatchment (C),Srinagar North (D),Srinagar (E)
and Dal Lake (F). On the basis of slope profile analysis, the
176
catchment is divided into the following five generalized
slope regions.
1. Region of low relief or Flatlands (below 5 degrees)
2. Region of gentle to moderate slope (5-10 degrees)
3. Region of gentle to undulating slope of the foothills
(10-20 degrees).
4. Region of moderate to steep slope (20-30 degrees)
5. Region of steep slope of the hills (30-4 0 degrees).
The average rainfall per annum at Srinagar is 650 mm
but at Dachigam is 870 mm. The temperature ranges from an
average daily maximum of 31 C and minimum of 15 C in July
to an average daily maximum of 4°C and minimum of -4 C in
January. Snow lies on the ground for nine months of the year
in the upper reaches of Dachigam. The Telbal nailah (approx.
flow length 39.0 kms.) carries water discharge of 60 cumecs.
The average water inflow is estimated at 292 x 10 cubic meters
6 6
and outflow is 261 x 10 cubic meters. Thus 31 x 10 cubic
meters of water are retained within the lake body. The nallah
descends from an elevation of above 3000 meters originating
from Marsar (Glacial/Snow-fed lake). The streams draining the
catchment are both perennial and intermittent. The unique
geological and topographic setting of the lake catchment
directs the surface and subsurface waters to emit into the
lake body. Hence the lake is a topographic sink within the
catchment area.
177
The catchment exhibits dendritic, parallel, trellis,
irregular and radial patterns. The drainage around the Dal
and Marsar lakes display centripetal network. The streams in
the catchment range from 1st to 5th orders, wherein 1st and
second predominates. The catchment has total number of 102
stream segments with average 3,00 bifurcation ratio, drainage
density 0,38 per km. and drainage texture 0.27 per sq, km.
area respectively. The drainage basin characteristics indicate
less of run-off and more infiltration within the catchment as
the drainage density is low. The low value of drainage density
is compatible with the geological characteristics of the catch
ment as it encompasses fractured basalts, cavernous limestones
and other permeable rock types. Numerous springs within the
catchment substantiate to the presence of subsurface hydraulic
network.
The Dal lake body is faced with numerous environmental
hazards. These include sedimentation,urban impact, waste
disposal and floral growth and development of Floating Gardens.
sedimentation of the order of 36,200 cubic meters per
year takes place within the lake body. The phenomenon is
goverried by geology, topography, climate and vegetation in
' the Catchment.
The lake catchment has diverse landuse pattern. The
vegetative land. Barren land. Agricultural land. Built-up
178
land and water bodies constitute 103.04, 190.55, 43.37, 25.08
and 19,40 (open water area 18.43 sq. km.) sq.km. respectively.
These form 27.04, 49.95, 11,37, 6.57 and 5,07 per cent
respectively of the catchment landuse pattern.
The lithounits of catchment are granites, slates,
phyllites, quartzltes, basalts, sandstones, shales, limestones,
conglomerates, boulders, pebbles, cobbles and river borne sands
ranging in age from Cambrian to Recent. The igneous terrain is
64.77 per cent, sedimentary 33,30 per cent and the rest accounts
the metamorphics. Karewas, alluvium and scree are softer litho
units; shales, slates and phyllites come next in the soft rock
category; limestones, sandstones and basalts are relatively
hard, whereas granites and quartzites are the hardest. The
softer units are about 27 per cent whereas harder units are
about 71 per cent. Ferromagnesian minerals, feldspars, quartz
and carbonates form the great percentage of parental mineral
association of the catchment rocks. Prolonged weathering action
of the lithounits release load in solution, suspension and as
bed load. Karewas, alluvium, scree, shales, slstes, phyllites,
and basalts and their derivatives produce load in the parti
culate form. Limestones produce load of solution. In general
the metal release from the catchment lithounits follows Ca,
Mg, P, Na, K, Pe, Mn, and Al. Pe and Al are least mobile while
the alkali ions are most mobile.
179
The Irnpact of landuse and geology upon the lake reveal
that metals introduced from irrigation return flows are Ca,
Mg, Na, K, HCO3/ CI, SO^, NO^* Sr and Cr; from the application
of fertilizers are N, P and K; from the solid waste disposal
are CI, SO^, Mn, and Fe besides other trace metals; from
detergents are Sr, Co, Zn, Mn, Fe, Ni, Cr and Ba; from
domestic sewage Ca, Mg, Na, K, CI, SO^ and NO^? from textile
dyeing, fur dressing and laundary are Zn, Cu, Nl, Cd, and Cr;
from recreational activities (auto, boatfuel, painted house
boats and small boats, and vehicular emissions) are Pb, Ni
and Cr, As far as natural sources are concerned, probably
the metals introduced from basalts and granites are Ca, Mg,
Fe, Na and K; from basalts, slates, phyllites, agglomeratic
slates and quartzites are Sr, Pb, Co, Zn, Cu, Ni and Cr; and
from metamorphic and sedimentary rocks are Mn, Cd and Ba. Rb
and Li are probably derived exclusively from the catchment
lithology. CO, and HCO^ are also released from the chemical
weathering of limestones. Fe, Ni and Li are absent in lake
waters which are probably carried with the sediments from
the catchment and get deposited on the lake bed.
The Dal lake is a shallow water body. It is a drainage
lake with urban to sub-urban status. The lake waters are mildly
to highly alkaline (pH ranges from 7.4 to 9.5), reasonably
clear, well oxygenated (D.O. ranges from 19.0 mg/1 to 7,0 mg/l).
180
have low specific conductivity (average value 136 micromhos
at 25°C), moderate to hard in alkalinity (ranges from 30 mg/1
to 140 mg/1). The lake waters are generally low in solids
(total solids 100 mg/1).
The average metal concentration recorded in the lake
waters in order of their decreasing concentration are Ca
(25.75), Mg (8.12), Na (0.44) and K (0.28); Pb (0.122), Mn
(0.075), Zn (0.056), Co (0.052), Sr (0.034), and Cu (0.024);
and concentration of Fe, Ni and Hg were not detected in the
water samples. In addition to this, the average concentrations
of trace metals and anions recorded at the four sampling
stations in the lake basins (during summer season) in order
of their decreasing concentrations are Ba (1.08), Cr (0.33),
Rb (0.04) and Cd (0.037) and SO^ (136.22), HCO3 (118.29),
CI (49.56) and CO3 (8.0). Li was not detected at the four
sampling stations of the lake basin.
The major (cations and anions) and trace metals recorded
in water samples at four sampling stations, when correlated
seasonally, revealed higher metal levels in lake waters during
autumn than during summer. Na and K do not depict any major
seasonal variation in their concentrations. The low concentration
of metals in lake waters during summer is due to the adequate
influx of snowmelt waters in the lake and probable occurrence
of evening rains during summer season over the lake body.
181
As far as the quality of lake water Is concerned, Sr,
Mn, Pb, Cd and Cr have been observed beyond the permissible
limits set by World Health Organisation. The analysis performed
upon the lake water samples, revealed in general that the trace
metals are below one ppm except in few samples.
On the basis of pzresent investigation the ionic compo
sition of the Dal Lake water could be arranged as Ca ">.
Mg •*"*""> Na^"^ K"** and SO^ " HCO3 Cl". Mg/Ca ratios were in
general found to be in the range of 1 i 3, thus Ca and Mg
carbonates are precipitated. It is inferred that for Dal Lake
the Mg/Ca ratios point to the presence of calcite in sediments
of the lake.
The fate of the metals in the lake waters have not been
evaluated, however, it can be said that metallic cations
combine chemically with soluble phosphorus to form precipitates
such as calcium phosphate. The incidence of low Na and K in
lake water could be ascribed to relatively low derivation of
these cations from the catchment lithology and probable uptake
of K by plants CO3, CI and SO^ can precipitate within the
lacustrine environment with other ions, HCO^ ion is probably
derived from litho-units. Sr remain in the diluted state in
lake waters. Local precipitation of sulphides is a possible
control mechanism for five of the metals Pb, Zn, Cu, Hg and
Od, but is probably not the chief controlling factor, because
of the shallow nature of the lake body. Adsorption is a
182
possible mechanism for all metals except Co, Ml and Cr, If
Cr Is assumed to be removed by local reduction, and the other
two metals by organic reactions, the existing reactions can be
fairly accounted for. Fe was not detected in lake waters
probably because of its affinity for oxygen to attain molecular
stability or precipitate as oxide or hydroxide in the lake
environment. Ni and Hg were found at undetectable levels.
Elemental mercury has a low solubility and the levels in
surface water will probably be highly insignificant irrespec
tive of the mercury input. Zn and Cu can probably combine with
the sulphate, forming the sulphates of these metals. The fate
of Rb and Cr remain unobvious and probably remain in the diluted
state because these are highly in trace concentrations in waters
at the four sampling stations in the lake sub-basins. Lithium
was not detectable at the four sampling stations of the Dal
lakis as the metal is typically related to mineral weathering
and is not derived from fertilizers and show no significant
relation to landuse.
It is added that N, P, K, Ca, Fe and Mg; and Mn, Zn,
Cu and Co are the major and trace metals probably required
by.the plants particularly by algae for their growth in the
Dal lake environment, that may be the reason that N, P, K, Fe,
Mg (compared to Ca), Zn, Cu and Co are found in low concentra
tions in the lake waters.
183
The Dal lake body has a differing compositional
characteristics with fine textured sediments (clay and
silt) in the central parts of sub-basins and coarse textured
sediments (medium to coarse grained sands) along the peripheral
zone. The lake sediments have been identified as alkaline (pH
ranging from 7.1 to 8.8). The organic and inorganic carbon
parallels the grain size distribution of the lake. Higher
values for the central sub-basins and low values along the
peripheral zone.
The major and trace metals detected in the surficial
sediments of the lake body include Ca, Mg, Na, K, Sr, Pb,
Co, Zn, Cu, Mn, Pe, Ni, Rb, Cd, Cr, Li and Ba. The average
metal concentration recorded in the lake sediments in order
of their decreasing concentrations are Ca (494.20), Pe (186.64),
Mg (146.03), Na (75.42) and K (57.75); Sr (7.89), Mn (4.429),
Zn (3.65) and Cr (1.62); Cu (0.908), Rb (0.74), Ni (0.72), Pb
(0,64), Ba (0.42) and Co (0.31); Cd (0.05) and Li (0.02).
P and N are higher in sediment phase than in water column.
Thus the average metal values in case of Pb, Co, Cu, Ni, Rb,
and Ba is under one ppm, and Cd and Li, are under 0.10 ppm
respectively.
Pine textured sediments, presence of organic* matter,
depth, pH and adsorption are some of the factors which control
abundance of metals in the Dal lake environment. Clay minerals
and organic matter effectively attenuate the dispersion of
metals•
184
The lake sediments are rich in Ca and Mg, probably
because of precipitation and sedimentation. Fe may form
metal oxide coating around the sediment particles, these
may grow by precipitation of iron hydroxide from saturated
suspension in the lake. The other reason for the abundance
of iron in the lake sediments may be due to decay of plants
during winters and subsequent incorporation in the lake
sediments. Pb and Cu may co-precipitate with hydrous oxides
of Fe and Mn. In general the major metals Ca, Mg, Na and K
get associated with other ions and form complexes. The trace
metals get adsorbed with the fine textured sediments and
organic matter.
The distribution and variation in concentration levels
of the metals in the surficial lake waters and sediments
reveal the following observations t-
(1) In lake waters Ca and Mg is high along peripheries,
no systematic zonation established in case of Na; K is high
on western and south-western area; Sr high on west and low
on northeast and east; Pb high in parts of sub-basins and
Co low in the central basins of lake; Zn tends to increase
towards centre of Bod Dal and Lokut Dal; Cu and Mn high in
south-western part of the lake (Figs. 21 and 22). Variation
diagrams reveal troughs and peaks in various sub-basins and
at sampling stations of the lake body with regard to metal
concentrations in lake waters (Figs. 23, 24, 25, 26 and 27).
185
(2) In lake sediments in general Ca, Mg, Na, K, Pb, Co,
Zn, Cu, Mn, Fe, Ni, Cd, Rb, Cr, Li and Ba are all found in
-> high concerfcration in Floating Garden Area and in the southwest
of the lake sediments (which also holds Floating Garden strips).
Central parts of lake sub-basin have sediments with enhanced
metal levels in case of K, Co, Mn, Fe, Ni, Rb and Li whereas
Sr is low in the central part of the lake and Ba more in the
lake waters at four sampling stations than in lake sediments.
A loop of low concentration is depicted by this metal in the
central part (Figs. 33, 34, 35 and 36). Fe, Ni, Li and Rb are
probably carried with the fine textured sediments from the
catchment and are deposited in the central basins and these
metals are either low or undetectable in the lake waters.
Variation diagrams (Figs. 37, 38, 39 and 40) reveal troughs and
peaks.in various sub-basins of the lake body with regard to
metal concentration in lake sediments.
It is apparent from these studies that the western and
south-western part of the lake body including Floating Garden
Area will emerge as a potential zone of inorganic metal
pollution in lake water and sediments in near future, in case
of sediments, the central parts of the sub-basins will also
emerge in future sediment metal accumulation zone because of
the occurrence of fine textured sediments and abundance of
organic matter. Sediments occurring close to human settlements
also show high metal levels.
186
To conclude with, the lake body has reduced in dimen
sions, its hydrology and hydrogeochemistry have been altered
sedimentation, deposition of decayed weed and solid waste
disposal has left only 2.74 meters (on an average) deep water
body which was formerly six meters (on an average) deep.
Extensive encroachments, infrasturcture and development of
Floating Gardens during the last thirty years have resulted
in diminishing the Dal Lake area from thirty two sq. km. (in
the year 1947) to eighteen sq. km. (presently), involving
about half the reduction in its area. Thus an area of 15.42
sq. km. has been left as open water area within the Dal lake
body excluding permanent land features (islands, roads and
marshy areas). Unplanned infrastructure has imparted sub-
basinal status to the Dal lake body, thus, restricting free
flow of the water leading stagnant zones in the lake particu
larly in the west and southwest. Population sector six and low
lying areas around lake periphery put maximum and alarming
deterioration and damage to the lake body. Domestic effluents,
dyeing, fur dressing, laundary activities, agricultural wastes
and metals from natural sources contribute to the enhanced
metal levels. The outflux of nutrients (N, P, and K) and other
metals (major and trace) does not take place, leading to the
ageing or eutrophication, deterioration in water quality and
enhancement in metal levels in the lake water and sediments.
There is a dispersion of metals from the Floating Garden Area
to other sub-basins of the lake body.
187
RECOMMENDATIONS FOR LAKE RESTORATION s
The Dal lake is in a State of peril. To save the lake
from multi-faceted environmental hazards viz., continuous
sedimentation (governed by geology, terrain, climate and
vegetation in the catchment area), excessive weed growth,
dumping of refuse and introduction of various metals,
reclamation of Floating Gardens within the lake and lateral
encroachment along lake periphery, various measures on long
and short term basis have to be adopted which are listed
below.
A. LONG TERM MEASURES i
1. Afforestation in the lake catchment. This would minimize
run-off and help in soil stabilization.
2. A three tier constructional development scheme around
and beyond the Dal lake periphery must be undertaken.
This measure would include construction of stone
pitched wall, followed by metalled road and finally
development of green belt parks/landscape development.
This will define the lake shoreline which in particular
is oblitered on the western side of the Dal lake,
3. Keeping urban expension away from the lake peripheries.
This measure can be accomplished by the thorough
iraplementation of the measure NO. 2.
188
4. Removal of Floating Gardens and evacuation of the
population settlements including commercial estab
lishments. This will help in the free movement of the
lake waters without restriction and obstacles and out-
flux of metals from the lake body.
5. All human settlements in the catchment be connected
with the sewerage arrangements including house-boats.
B. SHORT TERM MEASURES s
1. Construction of Desilting Basin near Telbal and check
dams on various silt carrying tributaries particularly
on the Dagwan Nallah.
2. Prevention of over-grazing in the catchment.
3. Deweeding of the excessive weeds from the lake, body,
4. Lessening of agricultural activities in the intimate
vicinity of lake periphery,
5. Grouping house-boats in arrangements convenient for
the provision of water and sewerage utilities.
189
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