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106
CHAPTER - V
PRESENT STATUS OF THE WATER CONSERVATION
STRUCTURES AND THEIR UTILITY.
For recharging the ground water table in watershed areas, large number of
water conservation structures such as Percolation Tanks, Check dams, K. T.
Weirs and Earthen Bunds have been constructed across the main nala and their
tributaries. [Table No. 33]
In the past there was a practice to construct Percolation Tanks and K. T.
Weirs beyond the foothill regions where nala becomes broad. However,
subsequently as a part of watershed development programmes, concrete or
masonry check dams of different sizes and Earthen Bunds were also constructed
at the higher reaches to get the benefit of percolated water for low lying areas and
to check the velocity of water thereby avoiding the soil erosion.
It seems that many of the water conservation structures might not have
been constructed meticulously by adapting civil engineering norms and observing
strict quality controls. It was observed that after the construction, these structures
were left uncared for and were deprived of proper maintenance. All such state of
affairs and measures in case of their repairs and modifications whatsoever have
been dealt within the present chapter.
Table No. 33 : Water Conservation Structures Constructed in Watershed Areas Studied
Sr. No.
Name of the Watershed
No. of K. T.
Weirs
No. of Earthen Bunds
No. of Masonry
Check Dams
No. of M.I. Tank/ P.T.
1 Nashera 03 ---- ---- 01 Abandoned 2 Ashewadi 09 04 --- ---- 3 M. Phule 06 --- --- ---- 4 Jai Yogeshwar 11 --- ---- ---- 5 Panoli --- --- 02 03 6 Hivre Bazar 04 07 02 02 7 Hivre Korda --- 09 ---- -- 8 Kachhe Ghati --- 04 05 --- 9 Kadwanchi 01 --- 03 ---
107
The present status of the water conservation structures and the
suggestions for their repairs and modifications are described below serially.
1) Watershed Area at Nashera
Three K.T. Weirs are constructed across Deobandh tributary to store water
of late rains. Generally gates of the K.T. Weir are installed in the second week of
September and are removed before the onset of the next monsoon to let
floodwater pass over. But it seems that this practice is not followed since the time
of construction of these K. T. weirs.
Three such K. T. Weirs were constructed at following locations. [Table No. 34]
Table No. 34 : Details of Water Conservation Structures across Deobandh Tributary
Name of the Structure Length in m. Height in m. Top width in m.
K. T. Weir No. 1 21.15 1.90 1.6
K. T. Weir No. 2 25.63 1.25 2.75
K. T. Weir No. 3 29 2.5 1
K.T. Weir No.1 [Fig. No. 157]
At Ch.619.5 m. K.T. Weir was constructed in 1997-98 [Fig. No. 157] having
following dimensions.
Length: 21.15 m. Height: 1.90 m. Top width: 1.6 m.
Two gates are provided to in the weir. The wall of the middle block of the
K.T. Weir has collapsed above the ground level due to washing away of masonry
blocks. As per the information given by the local people, although gates were
brought at the site alright to close the outlets of the K.T. Weir, they could not be
fitted in the K.T. Weir as the distance between the two channels of the outlet is
shorter than the width of the gates. Therefore gates were kept lying in abeyance
on the banks of Deobandh tributary below the highest flood level. During the
floods these gates were washed away and are now lying on the bed of Deobandh
tributary and are totally in rusted condition.
108
Suggestions:
It is suggested that new gates, with appropriate width may be fitted in the
K.T. Weir to effect storage of water. Similarly the portion of the dyke occurring
below the left abutment may be concreted and repairs of the fallen away portion at
the left abutment may be undertaken.
If this K.T. Weir is properly repaired the stored water in K.T. Weir may
percolate laterally through Dyke Nos. N-5 & N-6, which cut across the
submergence portion of K.T. Weir, and adjacent areas, may be benefited.
K.T. Weir No. 2 [Fig. No. 158]
It is constructed at Ch.1221.8 m. in 1997-98. Its dimensions are
Length: 25.63 m. Height: 1.25 m. Top width: 2.75 m.
Two gates are provided to it. [Fig.No.158] It was observed that in one
outlet, erosion of the concrete pavements provided at the sill and masonry work
made for the foundation are washed away creating voids. Through these voids
large percolation of stored water takes place and K.T. Weir becomes empty
immediately after the rainy season. According to the local people the gates are
installed permanently.
Suggestions:
It is suggested that repairs of the foundation work may be undertaken to
avoid percolation of water. Similarly, maintenance and installation of the new
gates may be entrusted to the authorities of the Grampanchayat.
K.T. Weir No. 3 [Fig. No. 159]
This K.T. Weir was constructed at ch.1429.65 m in the year 1997. having
dimensions
Length: 29 m. Height: 2.5 m. Top width: 1 m.
Two gates have been provided in this K.T. Weir. According to the
information given by the local people, the gates of this weir cannot be removed as
they have got stuck up tightly [Fig. No. 159] in the channels. Therefore, in rainy
season floods pass over the crest of the K.T. Weir. It was also told that heavy
leakage develops along the junction between the gates and the piers. Water also
percolates through the masonry work constructed at the foundation.
109
It was also observed that K.T. Weir has almost got silted up and Deobandh
tributary is filled up with silt and the mud upto crest of the K. T. Weir.
Suggestions:
It is suggested that desilting of the K. T. Weir and repairs of the foundation
work and the work of new packers at the gates may be undertaken immediately.
2) Ashewadi Watershed Area
The necessity of modifications and repairs of water conservation
structures constructed in the campus of proposed Medical College at
Ashewadi, district Nashik are given below.
In the watershed area of Ashewadi, 9 K. T. weirs and 4 earthen bunds
have been constructed to store run off of the area [Table No. 33 and 35- A
and B]
Table No. 35 - A : Details Showing Water Conservation Structures in Ashewadi Area
Name of the structure and stream No.
Length in m.
Height in m.
No. of Outlets
K T W No. – 1 ( S-1) 44.05 3.50 TWO Height 2.8 m., Width 1 m.
K T W No. –2 (S-2) 30.60 3.80 ONE Height 0.5 m. Top Width 6 m.
Height 3.1 m. Bottom Width 1 m.
K T W No. –3 (S-2) 47.84 1.64 TWO Height 0.94 m. Bottom Width 1 m.
K T W. No. – 4 (S-3) 26.20 3.55 ONE Height 0.5 m. Top Width 7.6 m
Height 3.3 m. Bottom Width 1m.
K T W. No– 5 (S-4) 25.00 3.40 ONE Top Width 6 m. Height 3.1 m
Bottom Width 1m.
K T W. No.– 6 (S-4) 75 6.00 TWO Height 4.80 m. Width 1m
K T W. No.– 7 (S-5) 30.14 3.55 ONE Height 2.75 m.
Width Top 6.18 m. and Bottom 1.0 m.
K T W. No. –8 ( S-6 ) 25.40 4.10 ONE Height 3.8 m.
Width Top 6.4 m. and Bottom 1 m.
110
Table No. 35 - B : Details Showing Earthen Bunds in Ashewadi Area
Number Length in m. Height in m. No. of Outlets
**E.B.– 1 (S -1) 26.0 2.0 ----------
E. B. – 2 (S -2) 50.8 2.20 ----------
E.B. – 3(S -5) 35.5 2.35 ----------
E. B. -4 (S -6) 26.5 2.40 ----------
* Kolhapur Type of Weir; ** Earthen Bunds
The present status of these structures and suggestions for their
modifications and repairs are given below serially.
K.T. Weir No. 1 [Fig. No. 160]
It has been constructed across Stream Number 1 (S-1) at the
southern boundary wall of the area. Its dimensions are [Fig. No. 160 ]
Length: 44.05 m. Height: 3.50 m.
Outlets: 2 (Height 2.80 m; Width 1 m of each outlet)
Towards downstream of K.T. Weir No. 1, at a distance of about 6.75
m, a waterfall having height 1.5 m is developed. [ Fig. No.161] During the
rainy season forceful floodwater would pass through the outlets. Due to the
force of the water, erosion of the face of the waterfall would occur and
gradually waterfall would migrate towards K.T. Weir No. 1. It is likely that in
due course of time the waterfall may migrate up to the toe of K.T. Weir No. 1
and may scour its foundation.
Suggestions:
1) As K.T. Weir No.1 is constructed at the southern border of the area,
the region, beyond the campus of the Medical College may get benefit of
percolation of water. To avoid loss of water by percolation from K.T. Weir
No. 1, it is suggested that a blanket of impervious soil may be spread in
reservoir area touching the u/s face of K.T. weir No. 1. So that, this K.T.
Weir would act as storage tank and water would be available during summer
season.
111
2) It is also suggested that, the weathered Amygdaloidal Basalt, which
is exposed towards downstream and at the base of the K. T. Weir, may be
covered by concrete giving Ogee Shape.
K.T. Weir No. 2
It has been constructed across Stream No. 2 (S-2). with following
dimensions
Length: 30.6 m.; Top Width : 0.60 m
Channel Width: 1 m; Height of the channel: 3.1 m
Outlets: 1, Upper outlet width: 0.6 m
Lower outlet width: 1.0 m; Height: 3.1 m
Immediately towards downstream of this structure loose material has been
dumped to avoid erosion of bed rock by impact of water. [Fig. No. 162] But during
the floods in rainy season this dumped material would get washed away and
would be deposited in the submergence area of Earthen Bund No.2 which is
constructed towards downstream at a distance of about 80.5 m
Suggestions:
1) It is suggested that the dumped material should be removed and concrete
apron should be provided on the bed of the Stream No. 2 up to a distance of 15
m. from the toe of K.T. Weir No.2.
2) It is also observed that the length of the weir is rather insufficient as
compared to the height of the water column, which would spread beyond both the
abutments. Due to which outflanking from the end portion of the K.T. Weir would
occur resulting in the erosion of the abutment portion.
3) Therefore, it is suggested that wing walls may be provided towards
upstream of K.T. Weir No. 2 to avoid outflanking and erosion of abutment portion.
[Fig. No. 163]
K.T. Weir No.3
This K.T. Weir has been constructed across Stream No.2 (S - 2) along the
southern boundary of the area and towards downstream of Earthen Bund No. 2.
Its dimensions are
112
Length - 47.84 m. Height - 1.64 m.
Outlets - Two (Height. = 0.94 m, Width = 1.0 m )
Suggestions:
1) In the reservoir area of this K.T. Weir, heap of loose rock and soil has
been dumped over a large area [Fig. No. 164] due to which storage capacity of
this K.T. Weir is reduced. Therefore it is suggested that the dumped material
should be removed.
2) Immediately towards downstream of the outlet, sheet jointed weathered
erodable Amygdaloidal Basalt is exposed up to a distance of 16 m. During rainy
season due to impact of the floodwater, erosion of weathered material may occur.
Therefore it is suggested that the weathered rock exposed towards downstream
of K.T. Weir may be covered by providing pitching of loose rock boulders so as to
avoid erosion of weathered Amygdaloidal Basalt.
3) The same weathered sheet jointed Amygdaloidal Basalt is also exposed
in the reservoir area. Therefore it is suggested that the weathered Amygdaloidal
Basalt, which is exposed towards u/s, may be covered by impervious soil.
K.T. Weir No.4
This K.T. Weir has been constructed across Stream No.3 (S - 3). It is
located at a distance of about 96 m towards u/s of the lower ring road having
dimensions
Length - 26.20 m : Height - 3.55 m
Outlets - Top Width = 7.6 m: Height = 0.5 m (Top Outlet)
Bottom width = 1 m (Bottom Outlet)
Fresh Amygdaloidal Basalt is exposed towards both upstream and
downstream of this structure. Towards downstream, gradient of the stream is
rather steep. A small waterfall has developed towards downstream at distance of
19.5 m. [Fig. No. 165]
The ends of this K. T. weir are abruptly terminated without anchoring in the
abutment rock. [Fig. No. 166] Therefore, to avoid outflanking of water during
113
torrential rains, towards u/s beyond both the ends of the structure loose mud is
stacked. [Fig. No. 166]
Suggestions:
1) It is suggested that in place of the mud which is stacked beyond both
end of the structure masonry wing wall may be provided.
2) It is also suggested that weathered Amygdaloidal Basalt which is
exposed towards downstream and on the face of the waterfall may be
covered by concrete giving Ogee Shape.
K.T. Weir No. 5
It is constructed across Stream No.4 (S-4) at a distance of 90 m from
Ring Road towards northern boundary. Its dimensions are
Length -25 m; Height - 3.4 m
Outlet – 01 (Ht =3.1m. Width of upper outlet 6 m.
Width of Lower outlet 1m.Height - 3.9)
Towards downstream of the structure, fresh Amygdaloidal Basalt is
exposed. Towards upstream beyond both the ends of the structure loose
mud is stacked to avoid outflanking of water during torrential rains.
Suggestions:
It is suggested that in place of the mud, which is stacked beyond both
end of the structure masonry wing wall, may be provided.
K.T. Weir No. 6 [Fig. No. 167]
This structure has been constructed across Stream No.4 (S-4)
Its dimensions are
Length - 75 m. Height - 6m. Outlet - 2 (ht-4.80 m. width 1 m. of each
outlet)
Towards downstream of the structure a short waterfall has developed. [Fig.
No. 167]
114
Towards upstream beyond both the ends of the structure loose mud
is stacked to avoid outflanking of water during torrential rains by washing
away of pile of mud.
Suggestions:
1) It is suggested that in place of the mud, which is stacked beyond both
end of the structure masonry wing wall, may be provided.
2) It is also suggested that weathered Amygdaloidal Basalt, which is
exposed towards downstream and on the face of the waterfall, may be
covered by concrete giving ogee shape.
K.T. Weir No. 7
This structure has been constructed across Stream No.5. Its
dimensions are
Length - 30.14 m. Height - 3.55 m. Outlet - 01(width of upper outlet 6
m, Width of bottom outlet 1.m Height of outlet=2.75 m)
The valley of Stream No.5 is quite broad and deep. As compared to
the depth of the valley, the height of the structure constructed is short.
Therefore, though valley has got quite large capacity to store water. The
height of the structure is inadequate.
Immediately towards d/s, a small waterfall is developed in sheet
jointed, weathered Amygdaloidal Basalt. [ Fig. No.168]
Suggestions
1) It is suggested that the height of the existing structure may be
increased to store maximum quantity of water.
2) The face of the waterfall occurring towards downstream may be lined
by masonry or concrete to avoid its migration towards K. T. Weir.
115
K.T. Weir No. 8
This structure has been constructed across Stream No.6 (S-6) in the
upstream side of stream, valley is quite deep in which Amygdaloidal Basalt is
exposed.
Its dimensions are
Length=25.40 m. Height=4.1 m. Outlet=01 (width of upstream outlet
6.4 m, Height of upstream outlet 0.5 m, Width of bottom 1.0m, Height of
bottom 3.7 m)
As compared to the depth of the valley, the height of the structure
constructed is short. Therefore, though valley has got quite large capacity to
store water, the height of the structure is inadequate [Fig. No. 169].
Suggestions:
It is suggested that the height of the existing structure may be
increased to store maximum quantity of water. If the height is not to be
raised beyond the ends of the structure wing walls may be constructed to
avoid out flanking. Immediately towards downstream of the structure, fresh
Amygdaloidal Basalt is exposed therefore there would not be erosion of tail
Channel.
K.T. Weir No. 9
This structure has been constructed across Stream No. (S - 6). Along
southern boundary of the area. [Fig. No.169] Its dimensions are
Length=63.24 m. ; Height: 4.1m
Outlet=02 Height 1 m of each outlet
Towards both downstream and upstream, weathered [Fig. No. 169]
Sheet jointed Amygdaloidal Basalt is exposed through which the stored
water from the stream may percolate beyond the campus of the area.
Towards downstream cultivated land is occurring closed to the right
bank of the stream. During high floods it is likely that cultivated land may get
washed away.
116
Suggestions:
It is suggested that a guide wall or pitching of rock up to considerable
height and distance may be constructed along the right bank of the stream to
channelize flow of water.
EARTHEN BUNDS
Earthen Bund No.1 ( E.B. No.1)
This bund has been constructed across Stream No. 1 (S-1). As valley
is shallow and no other water conservation structure has been constructed
towards upstream of the Bund No. 1 (S-1), water is collected at Earthen
Bund-1. [Fig. No. 170]
The dimensions of this Earthen Bund are
Length: 26.0 m. : Height: 2.0 m.
As the bund is constructed by only dumping loose soil without
providing zones and compaction of mud. Therefore, it is likely that voids may
be developed and loss of water may occur.
It is likely that outflanking may occur from the end portion of the
earthen bund.
Suggestions:
(i) It is suggested that the existing dumped mud may be properly
compacted.
(ii) To raise the height of the earthen bund, base width may be increased
proportionately.
(iii) It is suggested that pitching may be provided on upstream and
downstream face of the earthen bund.
Earthen Bund No.2 (E. B. No. 2)
It s constructed across Stream No.2 towards downstream of K.T. Weir
No .2. having dimensions
Length: 50.8 m. Height: 2.2 m
As the bund is constructed by only dumping loose soil without
providing zones and compaction of mud. [Fig. No. 171] Therefore, it is likely
that voids may be developed and loss of water may occur.
117
During rainy season, if the gates were not fitted in K.T. Weir No.2,
floodwater would accumulate in Earthen Bund No.2. The capacity of Earthen
Bund No.2 would not be sufficient to hold additional floodwater and in that case
water would overflow the crest of Earthen Bund No.2 and major portion of this
bund may be washed away.
Suggestions:
1) It is suggested that the existing dumped mud may be properly
compacted.
2) To raise the height of the earthen bund, base width may be increased
proportionately.
3) It is also suggested that pitching may be provided on upstream and
downstream face of the earthen bund.
4) For the sake of safety of this bund gates in K.T. Weir No.2 may be fitted
permanently and if required only regulated flood may be released by lifting
of the gates.
Earthen Bund No.3 ( E. B. No.3)
This has been constructed across Stream No.5 (S-5), towards downstream
of K.T. Weir No. 7 at the distance of 54 m.
Its dimensions are
Length: 35.5m. Height: 2.35 m.
During rainy season, if the gates were not fitted in K.T. Weir No.7,
concentrated flood would get accumulated in Earthen Bund No.3. The capacity of
Earthen Bund No.3 would not be sufficient to store entire flood and in that case
water would pass over the crest of Earthen Bund No.3 and major portion of this
bund may be washed away.
Suggestion:
For the sake of safety of this bund, gates in K.T. Weir No.7 may be fitted
permanently and if required only regulated flood may be released by lifting of the
gates.
118
Earthen Bund No. 4 (E. B. No.4)
This structure has been constructed across Stream No.6 (S-6) towards
downstream of K.T. Weir No. 8 at the distance of 44.2 m.
It was observed that quite heterogeneous, and small sized pieces of rocks
along with some soil are used in the construction. Due to which, the structure has
become weak and permeable.
During rainy season, if the gates were not fitted in K.T. Weir No.8,
concentrated flood would get accumulated in Earthen Bund No.4. The capacity of
Earthen Bund No.4 would not be sufficient to store entire flood and in that case
water would pass over the crest of Earthen Bund No.4 and major portion of this
bund may be washed away. Therefore, it is likely that water may percolate
through the body of this bund.
Suggestions:
For the sake of safety of this bund gates in K.T. Weir No.8 may be fitted
permanently and if required only regulated flood may be released by lifting of the
gates.
3) Mahatma Phule Society, Ozar, Dist .Nashik
As given in Table No. 5 six K.T. Weirs are constructed across Satwai Nala.
These K.T. weirs were constructed much before the diversion of canal water into
Satwai Nala. Therefore, these K.T. Weirs used to store floods of only late rains.
But subsequently when canal water was diverted, through Satwai Nala and to
store water outlets of these structures were permanently closed either by steel
gates or by constructing concrete diaphragms. After closing the gates, these K.T.
Weirs were started acting as storage tanks to store diverted water of the canal.
But no modifications in their structures were made like providing ogee shaped
downstream face of the gate and the bucket in front of it. The modifications
required are given in detail at the end of description of the structure.
During every rotation when K.T. Weirs become full of water, water
overflows from the crest of the K.T. Weir like a waterfall.
119
Condition of K.T. Weirs
K.T. Weir No. 1
It is located at Ch.140 m Dimensions are as follows
Length: 35. 5 m. Height: 2.5 m
Top width: 1 m. Outlet 3 (Height: 2.5m, Width: 2 m)
The outlets of this Weir are closed by concrete diaphragm. As stored water
overflows from the crest, it makes impact at the toe of the Weir causing erosion of
rock at the toe. This Weir is almost silted up. Only 1.5 m column of water stands
in the Weir [Fig. No. 49] reducing major storage capacity of the Weir. As per the
information given by Patkari after every rotation, water remains in the weir for 15
days, which indicates that percolation might have stopped through the rock
occurring along the banks of the nala due to silting.
K.T. Weir No. 2
It is located at Ch.550 m. Its dimensions are as follows
Length: 14 m. Top width: 0.65 m.
Height: 1.3 m. Outlets: 2 (Height - 0.08 m., Width- 0.9 m.)
The outlets of this Weir are closed by concrete diaphragm. As stored water
overflows from the crest, it makes impact at the toe causing erosion of the rock at
the toe. This weir is almost silted up and only short column of water is created.
[Fig. No. 50] As per the information given by Patkari, this Weir becomes empty
due to leakage developed between the bottom of the Weir and foundation of the
rock. In the toe region, gap is formed between the foundation rock and K.T. Weir,
which is clearly seen.
K.T. Weir No. 3
It is located at Ch. 847 m. Its dimensions are as follows
Length: 10.5 m. Height: 1 m.
Top width: 0.6 m. Outlets 2 Nos. (Height: 0.7 m; Width: 0.9 m.)
By constructing concrete diaphragm, outlets of this weir are permanently
closed towards downstream, jointed Compact Basalt is exposed. As water flows
120
from the top of the Weir towards downstream a narrow gully is formed in the bed
of the nala due to erosion.
As this Weir is almost silted up it never becomes empty and backwater
spreads up to Ch.1050 m. [Fig. No.172] Therefore, this Weir stores small quantity
of water released during every rotation.
K.T. Weir No. 4
It is located at Ch.1270 m.
Length: 19 m. Height: 1.2 m
Top width: 1 m. Outlets: 2 Nos. (Height: 0.9 m; Width: 1m)
The outlets of the Weir are permanently closed by concrete diaphragm.
The foundation of this Weir is taken on closely jointed Compact Basalt in which
spheroidal weathering is developed. These conditions are very much favourable
for percolation of water. However, a permanent standing pool of water remains in
the Weir. It is due to total silting up of the bed of the nala. Due to silting an
impervious blanket is formed on permeable strata. Therefore percolation is not
taking place [Fig. No. 52]
K.T. Weir No. 5
It is located at Ch.1663 m.
Length: 16 m. Height: 0.9 m.
Top width: 0.9 m. Outlets: 1 No. (Height: 0.9 m; Width: 0.9 m.)
Unlike K.T. Weir Nos. 1 to 4, gates are not permanently closed but they are
temporarily sealed by loose pieces of rock.
Just downstream of the gate, a narrow gully is formed due to erosion of the
rock. At the toe, mortar is removed and gap is formed between the body of the
Weir and the foundation rock.
As length of this Weir is insufficient and proper keying has not been made
in country rock, outflanking has taken place near the right abutment.
At the site of the Weir valley is almost flat therefore site is not suitable for
construction of Weir.
121
Though silting has taken place towards upstream of Weir, along the banks,
closely spaced jointed Compact Basalt is occurring, through which water
percolates laterally.
K.T. Weir No. 6
It is located at Ch.1750 m.
Length: 6.7 m. Height: 1.4 m
Top width: 0.9 m. Outlets: 2 (Height: 1.4 m.; Width: 2 m.)
"Niphad Co-operative Sugar Factory" constructed this Weir during the
financial year 1998-99 i.e. in the last phase of developmental activity.
It is suggested that the gates of the Weir may be removed at the beginning
of every rotation they may be closed subsequently, after filling of the K.T. Weir
No. 5, so that water will be stored in K.T. Weir No. 6 and minimum erosion at the
toe will take place if at all water overflows from the crest of this Weir.
On the basis of observations carried out of these structures
recommendations are suggested in the later part of this chapter.
Conditions of Minors and Diversion Channels:
A) Conditions of Minors:
It is observed that minors, after entering into the area of Mahatma Phule
Society, are in bad state of preservation. The erosion has taken place along
Minor No. 18 and at a number of places masonry lining has collapsed through
which leakage of water takes place in the area where no cultivation is undertaken.
[Fig.No.173] Due to loss of water through damaged portion of the minors effective
supply of water to the downstream farms is affected.
B) Condition of Diversion Channels:
Diversion channels are provided to divert water from Minor Nos. 17 and 18
to Satwai Nala. These diversion channels are in the form of unlined shallow
trenches through which water may be percolating giving benefit to the cultivated
area.
122
Repairs and Modifications of the Existing Structures
On Satwai Nala all Weirs are constructed as per the typical design of
Kolhapur Type of weirs. Kolhapur Type of weir is constructed to store water of the
late rains, which is received after mid September. Therefore gates are fitted after
15th October and gates are removed before the commencement of next rainy
season to pass the floods. It means the design of K.T. Weirs is not meant for
creating permanent storage of water. But in the area studied these Weirs are
being used for making permanent storages. As the outlets of the Weirs are
permanently closed either by fitting the steel gates or by providing concrete
diaphragm.
Therefore, after every rotation water fills up these structures and overflows
from the crest. As no energy dissipation arrangements have been made, water
from the crest of the weir falls towards downstream in the form of a waterfall
making concentrated impact in the region of the toe. It is observed that damage
has caused in the toe portion by forming gaps between the foundation rock and
the base of the K.T. Weirs As per the information given by Patkari, profuse
leakage takes place from the channels of the gates of the Weirs and also from the
foundation rock. If such percolation occurs continuously then the bond between
the masonry wall and the foundation rock would be weakened and in that case
structure may collapse.
Therefore, it is recommended that on priority basis proper modification in
existing structures be made as described in later part of this Chapter.
4) Jai Yogeshwar Society, Ozar, Dist. Nashik
Even though assured water supply was made available through Waghad
canal to Jai Yogeshwar Society. The society always experienced scarcity of water
for irrigation.
As the society lies in the tail end portion of the Waghad canal, sufficient
quantity of water never reaches up to the area of the society. Therefore, even
though all arrangement was made for distribution to provide canal water in the
entire area, water never reaches to the entire region of the society.
123
Therefore, it was decided to store rainwater in Ghagre nala by constructing
K .T. Weirs. Accordingly, 11 K.T. Weirs were constructed across it. [Table No. 8]
After the construction of these structures, for the first few years society got
benefit of percolated water. But gradually, percolation of water was dwindled and
at present it seems the structures have become defunct. It is mainly due to large
silt that has deposited in the submergence area of these structures and also due
to large percolation of water from the structures through voids, which are formed
in the foundation.
To get the full benefit of these structures the repairs and maintenance
should be taken immediately on war footing as given below.
K.T. Weir No.1
Length - 21.2 m. Top Width - 0.58 m. Height - 1.68 m.
It is constructed by using random rubble masonry. Two outlets are provided
in this K.T. Weir. But at the time of visit, the outlets are found to be open. It was
observed that thick blanket of silt is deposited in the submergence area of this
K.T. Weir.
K.T. Weir No.2 [Fig. No. 174 ]
Length - 8 m. Top Width - 1.96 m. Height - 1.06 m
Two outlets are provided to this K.T. Weir but they are permanently closed
by constructing concrete diaphragm. As in the region of this K.T. Weir, sheet
jointed amygdaloidal basalt is occurring and scouring of rock has developed close
to the toe portion of the weir. [Fig. No. 174]
It was also observed the pointing of the masonry structure is removed and
small voids are developed in the body of the weir by washing away of mortar used
in the construction.
As per the information given by the local people water from this K.T. Weir,
percolates through the body of the structure.
124
Suggestions:
It is suggested that as given in later part of this Chapter, a concrete apron,
covering the toe of the structure up to some distance may be provided to avoid
scouring and undermining of the toe portion.
Due to continuous percolation of water from the body of the structure,
masonry blocks would become loose and gradually they would be washed away.
K.T. Weir No.3
Length - 11.1 m. Top Width - 0.7 m. Height - 0.93 m
Two outlets are provided in this K.T. weir but they are permanently closed.
Similar to the K.T. Weir No.2 scouring has occurred close to the toe portion. Due
to which masonry used in the foundation is exposed. [Fig. No. 175]
Suggestions:
It is suggested that as given earlier, a concrete apron covering the toe of
the structure up to some distance may be provided to avoid scouring and
undermining of the toe portion.
Due to continuous percolation of water from the body of the structure,
masonry would become loose and gradually it would get washed away.
K.T. Weir
Length -11.8 m. Top Width - 0.6 m. Height - 0.8 m.
Two outlets have been provided to this structure. In the submergence area
silting has taken place.
It was observed that masonry from the wall has dislodged and totally
removed at places.
Suggestions:
It is suggested that pointing may be undertaken of the structure. Similarly
masonry work may be undertaken from where masonry blocks are removed.
It is also suggested that on the crest of this structure, thick concave shape
concrete lining may be made to provide protection from the flood water, to the
crest portion.
125
K.T. Weir No.5
Length - 11.3 m. Top Width - 0.65 m. Height - 0.7 m.
One outlet has been provided in this structure, which is permanently closed
by concrete diaphragm.
The scouring of the toe portion has occurred on the large scale exposing
the masonry used at the foundation [Fig. No. 176].
Suggestions:
It is suggested that as given in Chapter No. 5 downstream face of the K.T
weir may be modified giving ogee shape.
It is also suggested that thick concrete apron may be provided at the toe
portion up to some distance to avoid scouring of rock.
K.T. Weir No.6
Length: 16.8 m. Top Width - 0.56 m. Height - 0.63 m.
Two outlets have been provided in this but are permanently closed by
concrete diaphragm. Towards downstream of this structure, sheet jointed,
weathered amygdaloidal basalt is exposed. Due to removal of weathered
amygdaloidal basalt, during floods a shallow gully is formed in the nala.
Scouring of the foundation rock has occurred towards left of the structure.
[Fig. No. 177] similarly, pointing of the structure is removed at places and deep
notches are formed between two masonry blocks. Silting has occurred in the
submergence portion of this structure.
Suggestions:
It is suggested that on the crest of this structure, thick concave shaped
concrete lining may be made to provide protection from the flood water, to the
crest portion.
It is also suggested that pointing may be undertaken of the structure.
Similarly masonry work may be undertaken from where masonry blocks are
removed.
126
K.T. Weir No. 7
Length - 14.5 m. Top Width - 0.53 m. Height - 0.64 m.
Two outlets have been provided. Originally both the outlets were closed up
to the crest of the weir. But subsequently a portion below the crest of the gates
was demolished in order to guide the floods from the portion of the outlets. In the
portion scouring has taken place-exposing masonry used in the foundation. [Fig.
No. 178]
Suggestions:
It is suggested that on the crest of this structure, thick concave shape
concrete lining may be spread to provide protection from the floodwater, to the
crest portion.
It is also suggested that pointing of the structure may be undertaken.
Similarly masonry work may be undertaken from where masonry blocks are
removed.
K.T. Weir No.8
Length -15.2 m. Top Width - 0.51 m. Height - 0.62 m
The scouring has taken place at the toe of the structure. Silting has also
occurred in the submergence area.
Suggestions:
It is suggested that on the crest of this structure, thick concave shape
concrete lining may be made to provide protection from the flood water, to the
crest portion.
It is also suggested that pointing of the structure may be undertaken.
Similarly masonry work may be undertaken from where masonry blocks are
removed.
K.T. Weir No.9
Length -15.2 m. Top Width - 0.59 m. Height - 1.05 m.
Two outlets have been provided out of which one outlet is permanently
closed by concrete diaphragm. At the toe, scouring has taken place.
127
Suggestions:
It is suggested that on the crest of this structure, thick concave shape
concrete lining may be made to provide protection from the floodwater, to the
crest portion.
It is also suggested that pointing of the structure may be undertaken.
Similarly masonry work may be undertaken from where masonry blocks are
removed.
K.T. Weir No.10
Length -12.5 m. Top Width - 0.6 m. Height - 1 m.
One outlet has been provided in the structure which is permanently closed
by concrete diaphragm. Scouring at the toe portion has occurred exposing
masonry used in the construction, almost excessive silting has taken place in the
submergence area.
Suggestion
It is suggested that on crest of this structure, thick concave shaped
concrete lining may be made to provide protection from the floodwater, to the
crest portion.
It is also suggested that pointing may be undertaken of the structure.
Similarly masonry work may be undertaken from where masonry blocks are
removed.
K.T. Weir No.11
Length -16.05 m. Top Width - 0.6 m. Height - 0.65 m.
Two outlets have been provided and were permanently closed by concrete
diaphragm but out of this, one diaphragm was found to be in broken condition.
Scouring at the toe portion has occurred exposing masonry used in the
construction, almost excessive silting has taken place in the submergence area.
[Fig. No. 179]
128
To meet the deficiency of water which is by supplied by canal for the
development of the area, 11 successive K.T. Weirs were constructed across
Ghagre nala to store rainwater. In every K.T. Weir outlets are provided to release
the flow of water in rainy season. These gates are supposed to be closed to store
water of late rains. But it was informed by the local people that gates of some K.T.
Weirs were not at all installed as in K. T. Weir Nos. 2, 4 and 8. In case of some
K.T. Weirs, these are permanently closed by constructing concrete diaphragm for
e.g. in 1, 3,5,6,7,9,10 and 11.
During the studies of the K.T. weirs, it was observed that water flows either
through outlets or through the body and foundation of the K.T. Weir. Therefore
water is not getting impounded in these structures.
To make the use of these structures, it is suggested that all the gates
should be properly fitted in K. T. Weir Nos. 2, 4 and 8. Similarly undertaking
repairs should stop leakage from the body of K.T. Weir and through the
foundation. So that, all the K.T. Weirs will act as check dams and water will
remain in these structures even during summer.
If possible, it is suggested that height of every K.T. Weir may be raised to
store maximum quantity of water, to overcome the deficiency of water through
canal.
5) Panoli Watershed Area, Dist. Ahemadnagar
As hill ranges occurring along the boundaries of the area have steep
slopes, rainwater drains out quickly without getting any time to recharge the
groundwater potential. Therefore area faces acute scarcity of water even for
drinking purpose.
Due to steep slopes on hill ranges and due to indiscriminate deforestation
extensive denudation of soil cover has occurred. [Fig. No. 77]
To avoid denudation of soil cover, structures for soil conservation have
been constructed at the higher reaches.
Similarly, to increase groundwater potential a large number of water
conservation structures have also been constructed in the area as given below. [Fig. No. 77]
129
Water Conservation Structures
Three percolation tanks have been constructed in the area.[ Fig. No. 77]
Percolation Tank No.1 is constructed close to S-W boundary of the area on
Stream No.1, Percolation Tank No. 2 is constructed on Stream No. 3 towards N E
side of the area and Percolation Tank No. 3 is constructed beyond the northern
boundary of the area.
Check dams
Two check dams have been constructed across streams and about 21
small nala bunds have been constructed across different streams.
Details of Percolation Tanks
Percolation Tank No.1 [Fig. No. 77]
It is constructed on Stream No.1, towards southwest corner of the
watershed area. Zilla Parishad, Ahmadnagar, built the tank in the year 73-74. The
capacity of percolation tank is 574 cubic m. and command area is about 121 Ha.
This P.T. has got large catchment area as it is constructed at the lower
level on Stream No.1 Therefore, water occurs in this percolation tank throughout
the year.
The rock occurring in the vicinity of Percolation Tank is jointed compact
basalt. This Percolation Tank is constructed in the middle portion of Compact
Basalt where joints are well exposed, which can be seen beyond the left abutment
at higher level. As Percolation Tank is located in the jointed portion of compact
basalt Flow No.1, water percolates through percolation tank and downstream
area get benefit of the percolated water beyond the southern boundary of
watershed area and the wells located in the area of Wadule village get the benefit
of percolated water. This percolation tank was constructed about 25 years ago
and due to which large silting has occurred in it.
Percolation Tank No. 2 [Fig. No. 77]
This Percolation Tank has been constructed towards North-East of Panoli.
The tank is across Dara Nala and is located in Survey Nos. 615 and 617. The
capacity of this tank is about 280 cubic m. and 40 hectare of land is under
irrigation.
130
This P.T is constructed on amygdaloidal top portion of Flow No. 1, the
junction between top portions of Flow No. 1 and overlying Flow No. 2 is exposed
just below the F. R. L.
As the foundation is taken on fresh unjointed amygdaloidal top portion of
Flow No. 1 water does not percolate through Percolation Tank. However when
water level reaches up to F. R. L., water percolates through the junction between
Flow Nos. 1 & 2 and weathered sheet jointed amygdaloidal top portion of Flow
No. 1 is occurring along the rim of reservoir area and some wells located on the
bank of the nala get benefit of percolated water.
Percolation Tank No. 3 [Fig. No. 77]
This tank is located at a distance of about 3 km from Panoli- Parner road,
towards north of watershed area close to Parner ghat. It was constructed in
1981 under E.G.S. The capacity of the Percolation Tank is 141.60 Cu. m. and
about 25.80 Ha. of land is under irrigation.
The foundation of this tank has been taken on hydrothermally altered
greenish top portion of the flow. The greenish top portion of the Flow No. 1 is
vividly exposed on Panoli - Parner ghat. [Fig. No. 78] Hydrothermally altered
greenish top portion of the flow is thick. Due to weathering, sheet jointing is
developed in the upper portion up to some depth. But at the lower level, greenish
amygdaloidal top portion of the flow occurs in fresh condition without development
of joints.
The foundation of this P. T. is taken on sheet jointed, highly permeable,
amygdaloidal portion of the same flow. Due to which the tank becomes empty
through sheet-jointed portion of the rock.
The wells located towards downstream of this tank, do not yield water, as
water is not retained in sheet jointed amygdaloidal basalt and also in the lower
unjointed fresh Amygdaloidal Basalt.
Check Dams
Check Dam No. 1
It is located near Gaothan, its dimensions are
Length - 26 m. Height - 2.75 m. Top Width - 0.93 m.
Width of stilling basin - 1.6 m
131
It is constructed in cement concrete, downstream wall of the check dam is
sloping while upstream face is nearly vertical. Towards the right bank of this check
dam, columnar jointed Compact Basalt is exposed. The nala course is slightly
meandering and erosion has taken place along the right bank. Heavy silting has
taken place in the check dam, scouring has also occurred on the downstream of
check dam . Check Dam becomes empty due to leakage through columnar jointed
Compact Basalt occurring below the foundation.
Check Dam No. 2
It is located near Mr. Gaikwad’ s farm in Gut no. 8. Its dimensions are
Length: 23 m. Height: 2.05 m. Top Width: 0.97m
Width of stilling basin: 1.6 m.
The rock occurring on both sides of this check dam is columnar jointed
Compact Basalt. As the nala has gentle slope, heavy silting has taken place on
upstream side.
6) Hiwre Bazar Watershed Area, Dist. Ahmadnagar
A Large number of Water Conservation structures have been constructed
in Hivre Bazar watershed area as given in Table No.36 to improve groundwater
potential. The present status and modifications and repairs required there in are
given below.
Structures Constructed For Water Conservation
1) Percolation Tanks
2) Concrete Check Dams
3) K. T. Weirs
4) Small Earthen Bunds
132
Table No. 36 : Details of Water Conservation Structures across streams at Hiwre Bazar Watershed Area.
Sr. No. Chainage in m.
Name of the Structure
Length in m.
Height in m.
No. of Outlets
1 300 KTW-1 15 1.5 3
2 525 KTW -2 80 2.5 4
3 825 KTW- 3 70 2.5 4
4 1050 KTW- 4 50 2.5 5
5 1380 P T- 1 900 11 Waste Weir
6 2092 C D- 1 50 3.5 --
7 2767 C D- 2 35 2.6 ---
8 2917 P T – 2 700 9.6 Waste Weir
9 3442 E B- 1 150 5 Waste Weir
10 3552 E B – 2 120 5 Waste Weir
11 3652 E B- 3 120 5 Waste Weir
12 3752 E B- 4 80 5 Waste Weir
13 3900 E B- 5 50 5 Waste Weir
14 4050 E B- 6 31 5 Waste Weir
15 4350 E B -7 31 5 Waste Weir
( K. T. W. - Kolhapur Type of Weir ; C.D. - Check Dam; P. T. - Percolation Tank ;
E. B. - Earthen Bund )
The present state of the conditions and modifications and repairs required
to undertake of these structures such as Percolation tanks, K. T. Weirs and Check
dams are given below.
1) Percolation Tanks: [Table No. 36 ; Fig. Nos. 95 and 96]
Two percolation tanks have been constructed in Hivre Bazar watershed area
having capacity of 53 TCM to store water across main nala. [Fig. No.180 and 181]
Both the PT’s have been constructed having wave breakers [Fig.No.181] on the
u/s face and the spillway at the sides. [Fig. No.180 and 182]
For Percolation Tanks No. 1, no spillway bar [Fig. No.180] has been
constructed owing to the occurrence of quite hard broadly spaced jointed rock, in
the portion of the outlet. However, for Percolation Tank No. 2, a masonry spillway
bar has been provided in the form of ogee shaped downstream face.
133
It was observed that Acacia trees are luxuriantly growing on the wall of the
Percolation Tank. [Fig. No.181] The roots of the tress are bound to penetrate the
wall of earthen structure and avenues will develop for seepage of water, which
may harm the stability of the Percolation Tanks. Therefore, it is suggested that on
priority basis these trees should be cut down.
2) Check Dams: [Table No. 36; Fig. Nos. 95 and 96]
Two check dams have been constructed on the plateau of the area towards
west of Hivre Bazar village.
Both the check dams have been constructed as per the specifications
having end still weir and wing walls. But it was observed that wing walls towards
downstream are short in length therefore floodwater may damage the adjacent
farms. [Fig. Nos. 183 and 184]
3) K. T. Weirs: [Table No. 36; Fig. Nos. 95 and 96]
Four K. T. Weirs have been constructed in series near northern boundary
of watershed area. These K. T. Weirs are as per the specifications. The number of
gates for the K. T. Weirs depends up on the length of the K. T. Weir. In K. T. Weir
No. 1, towards downstream concrete diaphragm has been provided touching the
toe of the rock. [Fig. No. 185] In K. T. Weir No. 2, erosion close to the downstream
part near the toe has taken place due to lack of apron of concreting touching the
toe [Fig. No.186] In case of K. T. Weir No. 3, toe portion has been left unprotected
for want of apron touching the toe. [Fig.No. 187]
4) Earthen Bunds: [Table No. 36; Fig. Nos. 95 and 96]
Seven earthen bunds have been constructed across the main nala. These
earthen bunds are as per the specifications such as outlet, stone pitching on u/s
and downstream faces. [Fig. No. 188]
Almost all the earthen bunds have been constructed on weathered, sheet
Jointed, permeable Amygdaloidal Basalt and water percolates from these bunds
towards and beyond the banks up to some distance. Therefore these water
conservation structures have helped in achieving considerable increase in the
water levels in the surrounding wells.
134
7) Hiwre Korda Watershed Area, Dist. Ahmadnagar
As mentioned in Chapter No. 2, nine check dams have been taken
constructed in the area of Hivre Korda watershed.[ Table No. 33;Fig. Nos. 106
and 107] At the time of visit, the construction work was in progress and functions
of the structures could not be seen. [Fig. No. 189] otherwise the state of the most
of water conservation structures was in good condition. In the higher reaches of
the valley, various soil and water conservation structures such as Continuous
Contour Trenches, [Fig.No.112] Staggered Contour Trenches, Gulley Plugs have
been constructed. [Fig. Nos. 191 and 192]
In the Check Dam No. 3, water had collected during the previous season
before the construction work was completed.
It was observed that on the downstream face of Check Dam No. 3, there
were signs of leakage through the wall in the form of deposition of CaCO3 on the
downstream face of the wall and growth of moss on it [Fig. No.192]. This indicates
that percolation was taking place through the junction between the two masonry
blocks owing to lack of supervision and quality of work. It is suggested that to
check the percolation necessary repairs should be undertaken immediately in
Check Dam No. 2, as large silting has taken place.
8) Kachhe Ghati watershed area
Measures Taken to Improve The Groundwater Conditions And to
Protect Soil Cover :
During the drought of 1972, Zilla Parishad, Aurangabad constructed one
Percolation Tank, One Check Dam. However, as per the information given by the
local people, this Percolation Tank had not given much relief to the area to
improve ground water conditions and the area felt acute scarcity of water till the
watershed development work was undertaken by Dilasa Janvikas Pratisthan,
Aurangabad in the year 1996 and the work was completed in 2000. During this
period, following structures were constructed for water and soil conservation in the
area.
135
Table No. 37 : Details of Water Conservation Structures Constructed In
Kachhe Ghati Watershed Area
Type of Structure Length
(m.)
Height
(m.)
Width
(m.)
Spread of water towards
u/s (m.)
# C.D. No.1 12.5 2.0 1.05 133
C.D. No.2 19.0 2.6 1.0 150
C.D. No.3 21.0 2.5 1.0 25
C.D. No.4 30.3 3.4 1.0 30
C.D. No.5 18.0 2.0 1.0 75
*E. B. No.1 40.0 3.8 1.3 --
E. B. No.2 60.0 3.6 1.6 --
E. B. No.3 50.0 3.2 1.5 --
E. B. No.4 53.0 3.4 1.55 --
# C. D. Check Dam, * E. B. Earthen Bund
The main purpose of this study is to determine influence of geological
conditions on the utility of Water Conservation Structures. Therefore, more
emphasis is given on determining the field and water bearing characters of the
rocks occurring in the submergence and beneficiary areas of these Water
Conservation Structures. For this purpose geological mapping of the area was
carried out. The details of Water Conservation structures constructed are given
below. [Fig. No. 118]
Check Dam No. 1
It was constructed by Z. P. Aurangabad in 1972 at Ch. 450 m from the
southern boundary of the watershed area. It is constructed by using stone
masonry. Its dimensions are
Length – 12.5 m. Height- 2 m. Width – 1.05 m.
Immediately towards u/s of this check dam Vesicular Amygdaloidal top
portion of the Flow No. 1 is exposed. Scouring has occurred in the apron
provided. The apron is almost separated from the foundation rock. [Fig. No. 193]
136
Suggestions
The cement concrete should be filled up at the undermined portion. End
still weir may be constructed at the end of the apron by taking its foundation at
deeper level. So that undermining at the end still weir would not occur, as energy
dissipater to prevent the kinetic energy of overflowing of water and it would
overflow from the structure.
Dilasa Janvikas Pratisthan, Aurangabad, constructed Check dam Nos. 2 to 5.
Check Dam No. 2
It is constructed at Ch. 740 m. by using stone masonry. Its dimensions are
Length – 19 m. Height- 2 .6 m. Width – 1 m. Immediately towards u/s of this check dam highly weathered hydrothermally
altered, purple coloured top portion of Flow No. 2 is exposed up to considerable
distance. Scouring has occurred in the apron provided towards d/s. The apron is
almost separated from the underlying rock.
While observing the structure it was felt that no quality control was
maintained in the work. Similarly, workmanship is also poor. At places pointing is
removed. The scouring of wing wall constructed towards downstream along the
right abutment has occurred at the base due to removal of masonry blocks. It is
due to insufficient length of the wing wall. The end still weir is also in the very bad
state of preservation. [Fig. No. 194]
As per the information given by the local people profuse leakages occur
through the foundation of Check dam No. 2, this indicates that foundation has
either been only up to shallow depth or no quality measures were taken while
taking the foundation.
Suggestions
1) The repairs of the end still weir may be undertaken by providing thin apron
of concrete.
2) Lining of the bottom portion of wing wall may be undertaken on priority
basis otherwise wing wall may collapse. Fresh pointing may be undertaken in the
body of the structure.
137
3) Towards downstream of the end still weir a deep trench may be taken and
it may be filled up by black cotton soil up to the depth of 1 m. from the surface.
This filled up trench may be properly compacted. The upper portion of the trench
may be filled by concrete to provide protection to the underlying black cotton soil.
The width of the proposed trench may be 2 m. so that no scouring of foundation of
the end still weir would occur.
4) To avoid percolation of water from the foundation of the Check Dam, a
deep cut off may be taken touching the u/s face of the Check dam and Black
Cotton Soil may be filled in it.
Check Dam No. 3
It is constructed at Ch. 1100 m. by using stone masonry. Its dimensions are
Length – 21 m. Height - 2 .5 m. Width – 1 m.
The farmers, having their farms close to this check dam have given the
information that leakages have developed from the foundation and in immediate
downstream water gets stagnated in the nala, in which waterweeds are growing
luxuriantly. [Fig. No. 195]
1) The repairs of the end still weir may be undertaken by providing thin apron
of concrete.
2) Lining of the bottom portion of wing wall may be undertaken on priority
basis otherwise wing wall may collapse. Fresh pointing may be undertaken
in the body of the structure.
3) Towards downstream of the end still weir a deep trench may be taken and
filled up by black cotton soil up to the depth of 1 m. from the surface. This
filled up trench may be properly compacted. The upper portion of the
trench may be filled by concrete to provide protection to the underlying
black cotton soil. The width of the trench may be 2 m. so that no scouring
of foundation of the end still weir would occur.
4) To avoid percolation of water from the foundation of the Check Dam, a
deep cut off may be taken touching the u/s face of the Check dam and it
may be filled by black cotton soil.
138
Check Dam No. 4
It is constructed at Ch. 1790 m. It is constructed by using stone masonry. Its
dimensions are
Length – 30. 3 m. Height- 3.4 m. Width – 1 m.
The foundation is taken on the junction between Flow Nos. 4 and 5. At the
foundation, weathered Amygdaloidal Basalt is occurring, therefore water
percolates through it. Though this check dam appears in good condition [Fig. No.
196] from the downstream face of it water is oozing out from the joints of
masonry. [Fig. No.197] This indicates lack of supervision during the construction
work.
Suggestions
It is suggested that complete pointing of the downstream face may be
undertaken. Similarly, in summer when water level goes down and entire check
dam becomes empty, pointing in the u/s surface of the check dam may be
undertaken.
Check Dam No. 5
It is constructed at Ch. 3800 m. It is constructed by using stone masonry.
Its dimensions are
Length – 18 m. Height- 2 m. Width – 1 m.
Check Dam No. 5 is constructed on amygdaloidal top portion of Flow No 5.
At the time of visit due to torrential rains water had collected in this Check dam. In
general it is in good condition [Fig. No.198] However, the end of the apron
towards downstream is damaged due to flow of water. [Fig. No.199] It was
observed that apron is not anchored into the underlying rock and due to erosion a
gap has developed at the bottom of the apron.
Suggestions
The undermined portion of the apron should be filled up by cement
concrete. End still weir may be constructed at the end of the apron by taking its
foundation at deeper level. So that undermining of end still weir will be stopped
and it will also act as energy dissipater to prevent the kinetic energy of overflowing
water.
139
Percolation Tank
It was constructed by Minor Irrigation Division of Z. P. Aurangabad during
the drought of 1972. It is located at Ch. 1560 m. Its dimensions are
Length – 370 m. Height- 15 m. Top Width – 1.25 m.
In the region of Percolation Tank, Jointed Compact Basalt Flow No. 4 is
exposed. It becomes empty at the end of February which indicates that
percolating conditions are favourable at the site of P. T. As such the stored water
adequately percolates before the onset of the summer hence, water does not
stand for evaporation during summer.
Immediately after the construction of this tank the downstream region had
been benefited. But in due course of time silting is taking place in the Percolation
Tank and rate of percolation has rather decreased
After the construction of Percolation tank no maintenance work was
carried out. Pitching is dislodged from the u/s slope of the Percolation tank. Trees
have grown luxuriantly on the Percolation tank. [Fig. No.200] as a part of
maintenance works these trees may be uprooted and new pitching may be made
to avoid scouring due to wave action of water. [Fig. No. 201]
Earthen Bunds: ( E. B.)
Four earthen bunds have been constructed much at the higher level on
steep slope towards u/s of last check dam i. e C. D. No. 5. These are also
constructed across small streams that are originating from the N -E side of
watershed area, which eventually meets the main nala at the end of d/s.
Earthen Bund No. 1
It is constructed at Ch. 3900 m. with following dimensions :
Length – 40 m. Height- 3.8 m. Top Width – 1.30 m.
In the submergence area of this bund, Spheriodally Weathered Compact
Basalt is exposed which is clearly seen in the cut occurring on the bank of the
nala. [Fig. No. 141]
140
As percolating conditions are favourable due to occurrence of Spheriodally
Weathered Compact Basalt in the submergence area, downstream area gets
benefit from this bund.
Earthen Bund No. 2
It is constructed at Ch. 4200 m. having dimensions :
Length – 60 m. Height- 3.6 m. Top Width – 1.60 m
As this earthen bund is constructed on steep slope, water gets filled up in it
to F. R. L. during rainy season and water flows through the waste weir.
Earthen Bund No. 3:
It is constructed at about Ch. 4325 m. Its dimensions are
Length – 50 m. Height- 3.2 m. Top Width – 1.50 m.
This earthen bund is constructed immediately towards u/s of E. B. No.2,
therefore, back water of E. B. No. 2 almost touches the toe of this bund.
In the submergence area of this bund, Spheriodally Weathered Compact
Basalt is exposed through which percolated water merges into the reservoir of
E.B. No. 2, the wells taken close to the left bank get benefit from this bund.
Earthen Bund No. 4
It is constructed at Ch. 4400 m. Its dimensions are
Length – 53 m. Height- 3.4 m. Top Width – 1.55 m.
In the submergence area of this bund, Spheriodally Weathered Compact
Basalt is exposed. Therefore it provides suitable condition for percolation of water.
Along the tail Channel, Spheriodally Weathered Compact Basalt is exposed. But
as spheroids are large and weathering around every spheroid is thin, no erosion
of tail channel has taken place.
9) Kadwanchi Watershed Area
1) Structures Constructed Across Main Valley
Nine major check dams and one K.T. weir [Table No.17] have been
constructed across the main nala. In addition to these, 10 small check dams have
been constructed across the tributaries, meeting the main nala.
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The present state of conditions and suggestions for repairs of these
structures are given below serially. The numbers to these structures are serially
from u/s to d/s. However they are described below serially from downstream to
u/s.
Major Check Dam No.9
Towards u/s, wing wall constructed towards left bank is very much
damaged and collapsed. Highly weathered rock is exposed on which wing wall
has been constructed.
It was noticed that instead of construction of such thick wing, thin wing wall
would have served the purpose. On removal of thin coat of concrete, masonry had
dislodged from the wall. [Fig. No. 202]
Suggestions:
It is likely that in due course of time, during heavy floods the entire coat of
concrete would collapse and outflanking may occur from the left side of the check
dam.
Therefore it is suggested that, a masonry wing wall with cement mortar
having sufficient length may be constructed to avoid outflanking.
Major Check Dam No. 8
The wing wall constructed towards downstream on bank has almost
collapsed exposing highly weathered Amygdaloidal Basalt, on which walls were
constructed. During heavy floods when Check dam would start overflowing, it is
likely that entire wing wall may get washed away [Fig. No. 203] moreover scouring
of stilling basin has also occurred.
Suggestions
It is suggested that weathered Amygdaloidal Basalt may be excavated upto
required depth i.e. till fresh Amygdaloidal Basalt would be met with and by making
proper anchorage, a wing wall of concrete or masonry may be constructed upto
desired length.
The stilling basin needs to be repaired. The coat of concrete may be
provided towards downstream to cover weathered Amygdaloidal Basalt.
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Major Check Dam No. 7
Though wing walls are intact, scouring of end portion of apron constructed
towards downstream is damaged and undermining has occurred [Fig. No. 204 ]
Suggestions
The undermined portion and the apron may be filled up with cement
concrete. End still weir may be constructed at the end of the apron by taking its
foundation at the deeper level. So that undermining of the end still weir would not
occur and it would act as energy dissipater to prevent kinetic energy of flowing
water from the structure.
Major Check Dam No. 6
Suggestion
Similar to check dam Nos. 7 and 8, towards d/s, wing wall has been very
much damaged due to impact of floods. It is suggested that new thick wing wall of
concrete or masonry having sufficient length may be constructed.
Major Check Dam No. 5
It is in good condition.
Major Check Dam No. 4
Heavy silting [Fig No.205] has taken place in this the reservoir area
reducing its storage capacity to store designed quantity of water.
Suggestion
Similar to Major Check Dam No.4, almost in all the water conservation
structures silting has taken place. It is suggested that silt may be removed during
every summer season, before the onset of the monsoon.
K.T.Weir
As it is constructed much prior to the development activity undertaken by
M.S.S.M. The upper gates were not at all installed after the construction.
Therefore water could not get stored in the K.T. weir up to its full capacity [Fig.
No. 206]
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Suggestions
It is suggested that repairs of K.T. Weir may be undertaken meticulously
and gates may be installed to make the use of K.T. Weir for storing floods of late
rains.
The K.T. Weir may be handed over to the Gram Panchayat for its further
maintenance.
Major Check Dam Nos. 3 and 2
These are in good condition.
Major Check Dam No.1
Immediately towards downstream of end still weir, closely spaced jointed
spheroidally weathered Compact Basalt is occurring. As every spheroid occurs
almost as loose rock, during the floods scouring of the foundation of end still weir
will take place. It is observed that heavy silting has taken place in Check Dam No.
1. [Fig. No.207] the bed of the nala is also covered by bushes which binds the silt
through spreading of roots.
Suggestion
1) Due to occurrence of spheroidally weathered Compact Basalt, erosion
towards downstream of end still weir may take place. Therefore it is suggested
that the bed of the nala towards downstream of the end still weir may be covered
by concrete up to required distance.
2) It is also suggested that desilting and removal of bushes may be
undertaken during pre monsoon period.
2) Structures Constructed Across Tributaries
Small Check Dam No. T- 8
Towards the u/s of this small check dam, highly weathered amygdaloidal
basalt is exposed on the banks of the tributary. After the water column was
created in the structure, the weathered murum started collapsing in the bed of the
tributary and thereby reducing its storage capacity.
It is likely that outflanking may occur due to collapsing of highly weathered
amygdaloidal basalt from the abutment portion.
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Suggestions
1) Towards u/s, wing walls of the adequate length may be constructed to
avoid outflanking.
2) The Vertical natural cuts occurring on the banks of the tributary may be
dressed to stabilize the portion of banks.
Small Check Dam No. T- 7
Although wing walls have been constructed towards u/s their lengths are
inadequate. Due to which, it is likely that outflanking may occur due to collapsing
of highly weathered Amygdaloidal Basalt from the abutment portion.
Suggestions
1) It is suggested that, the length of the wing walls may be extended at least
by 5 m. towards u/s to avoid out flanking.
2) As mentioned above, the banks of the tributary may be dressed to stabilize
the portion of the banks.
Utility of Water Conservation Structures from Structural point of View
As mentioned above, four types of Water conservation Structures viz. K. T.
Weirs, Check Dams, Percolation Tanks and Earthen Bunds have been
constructed in 9 watershed areas within the span of study. Their utility from
structural point of view is described below.
A) K.T. Weirs
K.T. weirs are constructed to store water of late rains. Therefore, their
gates are installed by 15th October and gates are removed before the onset of the
next monsoon to pass floods after heavy showers. But it was noticed that the
timetable of operation of the gates is not generally followed.
Following shortcomings were revealed in the K.T. weirs constructed in
watershed areas.
1) Undersized Gates:
In case of K.T. Weir No.1 in Nashera , the gates were lying in abeyance
,as the width of gates is less than the distance between the two channels of the
outlets. The gates are brought to the site but not fitted in the K.T. weir and were
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left either on the bed or on the banks of the nala. The gates which are lying on the
bed of the nala are either washed away along with the flood or may be rusted.
2) No gates are fitted:
In Kadwanchi watershed area, upper gates of the K.T. weir are not at all
fitted. Therefore K.T. weir does not get filled upto its full capacity.[Fig. No. 206]
3) Gates are stuck up in the channel:
It was also observed that, in case of some K.T. weirs the gates are jammed
and stuck up in the channel due to which they could not be removed before the
onset of monsoon. Therefore outflanking of floodwater also occurs damaging the
adjacent cultivated area, viz. K.T. Weir No. 2 and 3 in Nashera [Fig. No. 159]
4) Total silting of K.T. Weirs:
Similarly in case of some K.T. weirs due to permanent closing down of the
gates, excessive silting has occurred even up to the crest of the K.T.Weir viz.
K.T.weir Nos. 2 and 3 in Nashera same is the case with all K.T. Weirs constructed
in Mahatma Phule and Jai Yogeshwar Societies in Ozar,Dist .Nashik [Fig. Nos.
49 and 50]
5) Erosion at the toe of K.T. Weir and removal of masonry blocks:
As gates are permanently fitted, water from the K.T weir falls from its crest
in its toe region like a waterfall creating erosion of country rock and damaging the
construction work of the K.T. weir viz. K.T. weir No. 3 at Nashera, K.T weir Nos. 1
and 4 in Ashewadi, .[Fig. No. 161] K.T. weir Nos. 1,2,5 and 6 Mahatma Phule,
K.T. weir Nos. 2,3,5,7,8,9,10 and 11 in Jai Yogeshwar area and a K.T. weir in
Kadwanchi area.
6) Outflanking from the K.T. weirs:
In case of some K.T. Weirs, they are not properly anchored into the
abutment area and no wing walls have been constructed. Due to which during
high floods outflanking occurs (viz. K.T. weir No. 8 in Kadwanchi) by washing
away the cultivated land in the adjacent area. viz. K.T. Weir Nos. 2, 4 and in
Ashewadi,[Fig. No.163] and all K.T. weirs in Mahatma Phule and Jai Yogeshwar
societies.
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7) Formation of Gullies and waterfall in the downstream portion:
As in case of some K. T. Weirs weathered rock is occurring in vicinity and
due to lack of concrete apron towards downstream portion waterfall has
developed. Viz. K. T. weir Nos. 1,4,6 and 7 of Ashewadi, 3 and 5 in Mahatma
Phule Society, and 6 in Jai Yogeshwar Society.
8) Lack of maintenance of the rubber packers:
In case of K.T. weir No. 3 in Nashera, the stored water comes out forcefully
through the channels of the K.T weir due to lack of maintenance of the rubber
packers came out.
9) Lack of modification in the structure:
In case of Mahatma Phule and Jai Yogeshwar societies, outlets of the K.T.
weir are permanently closed by constructing concrete diaphragm so that K.T.
weirs would act as storage structure like check dam. However, no modifications in
the K.T. weir have been made to allow the flow of water without damaging toe
portion of K.T. weir. Therefore, extensive erosion has taken place at the toe
portion there by undermining of foundation of the K.T. weir. As a result in K.T.
Weir No. 2 in Hivre Bazar area, water rushes out through the undermined portions
of the K.T weir.
B) Check Dams (C. D. )
Masonry check dams have been constructed in large numbers in all
watershed areas studied. Every check dam gets filled up to its rim and excess
water which could not be stored in the check dam and passes towards
downstream over the crest of Check dams. But no elaborate energy dissipation
arrangements have been made in all the check dams.
1) Flat surface of the crest:
Instead of giving convex shape to the check dams the crest of each and
every dam is flat. Due to which water overflows from the check dams and falls
towards downstream getting some trajectory. Due to impact of falling water, thin
coat of cement plaster provided on the flat surface of the crest has been washed
away exposing inner masonry blocks. In case of some check dams, even the
masonry blocks from the crest are dislodged.
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2) Lack of ogee shape downstream face:
To every overflow structure, its downstream face is given ogee shape so
that water passes over the crest will falls down towards downstream touching the
surface of the overflow structure. But in all the check dams so constructed the
downstream face has been given a slope of 1: 0.25. Therefore, some flood water
directly colloids on the rock occurring close to the toe of the structure causing
erosion of the rock therein.
3) Lack of concrete lining on the downstream surface of the wall :
Similarly, on the downstream face of the structure no lining of concrete has
been laid.. Masonry blocks are exposed on the downstream face of check dam.
Due to impact of the falling of water, pointing around the masonry blocks are
removed developing deep gaps between them, as a result masonry blocks have
become loose. Viz. C. D. No. 5 in Kachhe Ghati [ Fig. Nos. 47 and 199], C. D. No.
9 in Kadwanchi { Fig. No. 202]
4) Inadequate width and depth of the bucket at the toe:
Except at a few check dams, bucket has been provided at the toe.
However the depth and width of the bucket is very small. Therefore these buckets
do not serve the purpose of dissipating the kinetic energy of water. Therefore it is
suggested that deep and broad buckets may be provided at the toe of all the
check dams. Viz. C. D. Nos. 1 and 2 in Kachhe Ghati.
5) Inadequate height and lack of anchorage of the end still weir:
Wherever buckets are constructed they have been provided with very short
wall to act as end still weir. However these walls have been constructed without
taking foundation on the underlying fresh rock. Due to which almost undermining
of end still weirs have occurred. It is suggested that its foundation should be
anchored in underlying hard rock and by keeping sufficient height over the
surface. Viz. C. D. Nos. 1[Fig. No. 193] C. D.Nos. 2 and 5 in Kachhe Ghati [Fig.
Nos 194 and 199] and C. D. Nos.7 and 8 in Kadwanchi[Fig. Nos. 203 and 204]
6) Leakage through the body of the check dam:
It is observed that in case of some check dams, leakages have developed
through the pointing of the wall. Due to continuous leakage through the body,
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large voids would be created removing masonry blocks leading to profuse
leakage. Viz. C. D. No.3 [Fig. No. 190] in Hivre Korda, C.D. Nos. 3 and 4 in
Kachhe Ghati.[ Fig. Nos. 195 and 197]
7) Lack of anchorage of end portion:
It is observed that in almost all the check dams the ends of the check dams
are merely abutted on the adjacent weathered rock without providing proper
anchorage in the abutment rock up to sufficient depth.
8) Inadequate length of the wing walls:
It is also observed in majority of the check dams that wing walls towards
u/s and downstream have very short length, due to which outflanking has
occurred in some check dams and adjacent cultivated land has been washed out.
Similarly, the floods that have spread from the check dams have damaged
the cultivated land beyond the banks of the nala towards d/s. Viz. C. D. Nos. 1and
2 in Hivre Bazar, [Fig. No. 183 and 184], C. D. No. 2 in Kachhe Ghati.[ Fig. No.
194] C. D. Nos. 6 & 8 in Kadwanchi [Fig. No. 203]
9) Excessive silting:
In almost all the check dams, heavy silting has occurred reducing the
storage capacity of the structures. Due to deposition of the silt, waterweeds have
grown in some check dams. Viz. C. D. Nos.1, 2 in Panoli, 2 in Hivre Korda C. D.
Nos. 1 and 4 in Kadwanchi [Fig. Nos. 207 and 205 respectively.]
10) Side collapses of the bank of the nala:
It was also observed that towards u/s when water gets stored in the check
dams, the sides of the banks have found to be collapsed. Therefore, it is
necessary to stabilize the banks by giving gentle slopes up to the end of
submergence area.
Percolation Tanks and Earthen Bunds
Percolation tanks (P. T.) and Earthen Bunds (E. B.) have been constructed
in some watershed areas. P. T’s have been constructed by Z.P. across the major
nalas much prior to the area having been taken up for the development by
developing agency. Where as earthen bunds have been constructed by the
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development agency in large number across the small tributaries existing in the
watershed areas.
C) Earthen Bunds ( E. B.)
Lack of adapting technical norms in the construction of E.B
It was observed that the E.B.’s seem to have not been constructed by following
the technical norms, merely some earthen bunds have been constructed dumping
loose soil on the bed of the tributary either without any compaction or providing
proper zoning. viz. All E. B.’s in Ashewadi area.[ Fig. Nos. 170 and 171]
In some earthen bunds, neither pitching has been provided nor they are
kinked into the abutments slopes by taking trenches on u/s & downstream slopes.
e.g. All E. B.’s in Ashewadi area.
D) Percolation Tanks
In most of the percolation tanks it was observed that pitching on u/s &
downstream faces are dislodged by erosion thereby exposing material used for
the construction of P. T. viz. P. T. In Kachhe Ghati [Fig. No. 201]
It was also observed that on the wall of the P. T.’s large trees are growing
in profusion. The roots of these trees in due course of time may create cracks and
voids in the wall causing profuse leakage. viz. P. T. In Hivre Bazar and Kachhe
Ghati[ Fig. Nos. 181 and 200]
It was also observed that heavy silting has occurred in P.T.’s creating
impervious blanket in the reservoir portion due to which percolation is totally
hampered and the stored water in the P.T. is left behind only to be lost by the way
of evaporation without giving benefit to the downstream region. [Fig. No. 200]
Recommendations for the modification of water Conservation Structures. In all the check dams so far constructed in watershed areas studied, no
energy dissipation arrangements have been provided. The check dams have
been constructed similar to the masonry compound walls. [Fig, No. 208] Ideally
every structure should have curviform crest, ogee shape downstream face and
broad deep bucket with end still weir at the front. [Fig.No.209] But such
configuration has not been adapted in the existing check dams.
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Therefore, to avoid erosion of the rock at the toe, all these check dams
require suitable modifications to achieve energy dissipation. Following simple
modifications are suggested without making much alteration in the original
structures.
A) The downstream face of the check dams may be modified in such a way
that it would acquire ogee shape with broad and deep bucket in front of the toe
and at the end still weir [Fig.No.210] But for such modification, much alteration
would be required and it would be a costly proposition. Moreover, there would
also be problem in creating proper bond between the wall of the check dam and
the new masonry work. Therefore instead of going for costly affair following
modification may be adapted.
B) Touching the downstream face of the check dam, rather broad masonry
steps may be constructed in a series so as to dissipate gradually and
successively kinetic energy of the flow of water to arrest the erosion in the toe
portion of the check dam. [Fig.No.211]
Again in case of K.T. Weir where gates are permanently closed, similar
arrangements may be made for energy dissipation to avoid erosion of the rock at
the toe portion.
C) Alternatively, at the toe of KT Weir and also at the toe of check dams a
thick apron of rich concrete extending much towards downstream may be
provided to avoid erosion of the rock. [Fig.No.212]
Maintenance of the Water Conservation Structures Constructed
After the construction of water conservation structures, it seems that they
have been not been paid due attention by the local people and also by developing
agency Eventually much needed maintenance measures were overlooked
causing dilapidation of the structures. Therefore it is suggested that some funds
may be reserved for the maintenance from time to time. During the work of
construction itself, maintenance should be initiated simultaneously and local
artisans may be trained to undertake minor repairs of the structures.
Subsequently, the maintenance work should be entrusted to the local
Grampanchayat.