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Presented at the 2nd Phase Planning and Review Workshop of the Indo-Ganges Basin Focal Project, 24-25 February, 2009, Haryana, India
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Impact of Climate Change on Ganga River Basin
A. K. Gosain
Professor of Civil Engineering
Indian Institute of Technology Delhi
Presentation layout
� Methodology used – SWAT model
� SWAT implementation on Indian basins for climate change impact assessment
� Detailed results of Ganga basin
� Gaps in the study
SWAT Hydrological model
� SWRRB - Early 80's -Modified CREAMS
� SWAT - Early 90's -Modified SWRRBReach Routing StructureFlexible Watershed
Configurations
� TAES-IIT Delhi MoA - 1996, to collaborate in further development of the model
Model Objectives
� Predict the impact of man-made changes & management practices
� Predict the impact of global warming
� water, sediment, nutrient and pesticide yields
� generate alternate scenarios
� conduct vulnerability assessment
Can map wide range of features
� Pond & reservoir storage
� Crop growth & irrigation
� Groundwater flow
� Reach routing
� Nutrient & pesticide loading
� Water transfer
Major inputs
� Weather � Daily Precipitation
� Max - Min Temperature
� Solar Radiation
� Wind Speed & Relative Humidity
� Terrain
� Landuse
� Soil
Crop Growth
� Generic model - Parameterized by plant database used by EPIC and WEPP
� Phenological Development - Daily heat unit accumulation
� Potential Growth - Interception of solar radiation (LAI, solar radiation)
� Growth Constraints - Water, temperature, nitrogen & phosphorous stress
Model Output
� Model outputs include all the water balance component at various levels i.e., basin, subbasin or watershed level and at intervals of daily, monthly or annual
� surface runoff� evapotranspiration� lateral flow� recharge� percolation� sediment yield� Nutrients
Initial National Communication to UNFCCC
� Coordinated by MoEF
� A large number of groups involved to undertake studies in various sectors
� Water Resources entrusted to IIT Delhi
� The communication has been made by the MoEF to UNFCC
Objectives of the Study
� To quantify the impact of the climate change on the water resources of the country
� Identify Hotspots
� Identify Adaptation & Coping strategies
Data Used for Modeling
� Contour: 100 m interval - 1:250,000
� DEM: 1km grid, generated using ArcView
� Land use: 1:2M USGS
� Soil: 1:5M FAO
� Drainage: 1:250,000
� Weather: Data generated by the “Hadley Centre for Climate Prediction” U.K. at a resolution of 0.44° X 0.44° latitude by longitude (HadRM2) from IITM, Pune
River Basins Modeled
Annual mean water balance for Control and GHG climate scenarios in different river basins
Trends in Waterbalance Components (Control and GHG Climate Scenarios)
0
200
400
600
800
1000
1200
1400
1600
1800
Cauvery Brahmani Godavari Krishna Luni Mahanadi Mahi Narmada Pennar Tapi Ganga Sabarmati
Valu
e (
mm
)
Rain (Control) Rain (GHG) Runoff (Control) Runoff (GHG) AET (Control) AET (GHG)
Percent change in mean annual water balance for Control and GHG climate scenarios
-80
-60
-40
-20
0
20
40
Mah
an
ad
i
Bra
hm
an
i
Gan
ga
Go
davari
Cau
very
Narm
ad
a
Tap
i
Kri
sh
na
Pen
nar
Mah
i
Lu
ni
Sab
arm
ati
River Basins
Ch
an
ge
fro
m C
urr
en
t to
GH
G S
ce
na
rio
(%
)
Rainfall Runoff ET
Assumptions and Coarseness of the Data Used
� Daily RCM data not reconciled for its accuracy
� Landuse has been assumed to be same
� Water bodies including reservoirs could not be incorporated at this stage due to lack of data
Ganga River Basin Annual water balance components
0
200
400
600
800
1000
1200
1400
1600
1800
19
81
19
82
19
83
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
Year
Va
lue
(m
m)
PrecipitationETWater Yield
Control Scenario
0
200
400
600
800
1000
1200
1400
1600
1800
20
41
20
42
20
43
20
44
20
45
20
46
20
47
20
48
20
49
20
50
20
51
20
52
20
53
20
54
20
55
20
56
20
57
20
58
20
59
20
60
Year
Va
lue
(m
m)
PrecipitationETWater Yield
GHG Scenario
Monthly water balance components for Ganga river basin
0
50
100
150
200
250
300
350
Ja
n
Fe
b
Ma
r
Ap
r
Ma
y
Ju
n
Ju
l
Au
g
Se
p
Oct
No
v
De
c
Year
Valu
e (
mm
)
PrecipitationETWater Yield
Control
Scenario
0
50
100
150
200
250
300
350
Ja
n
Fe
b
Ma
r
Ap
r
Ma
y
Ju
n
Jul
Au
g
Se
p
Oct
Nov
De
c
Year
Valu
e (
mm
)
PrecipitationETWater Yield
GHG
Change in Monthly water balance components for Ganga river basin
-30
-20
-10
0
10
20
30
40
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Year
Va
lue
(m
m)
PrecipitationETWater Yield
Change in monthly water balance for
Control and GHG climate scenarios
-40
-20
0
20
40
60
80
100
120
140
160
180
Ja
n
Fe
b
Ma
r
Ap
r
Ma
y
Ju
n
Ju
l
Au
g
Se
p
Oct
No
v
De
c
Year
Va
lue
(%
)
PrecipitationETWater Yield
Change (%) in monthly water balance
for Control and GHG climate scenarios
Sub-basin Water Balance components for Ganga Basin
0
1000
2000
3000
4000
5000
6000
7000
1 2 3 4 5 6 7 8 9 10 11 12 1314 15 16 17 18 192021 22 23 24 25 2627 28 29
Subbasin
Va
lue
s (
mm
)
PrecipitationETWater Yield
Control Scenario
0
1000
2000
3000
4000
5000
6000
7000
1 2 3 4 5 6 7 8 9 101112 1314 15 1617 181920 2122 23 2425 262728 29
Subbasin
Va
lue
s (
mm
)
PrecipitationETWater Yield
GHG Scenario
Ganga River – Annual Peak
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
1 3 5 7 9 11 13 15 17 19
Year Number
An
nu
al d
ail
y p
eak d
isch
arg
e
(cu
mecs)
Control ScenarioSubbasin 11
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
1 3 5 7 9 11 13 15 17 19
Year Number
An
nu
al d
aily p
ea
k d
isch
arg
e
(cu
mecs)
GHG ScenarioSubbasin 11
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
1 3 5 7 9 11 13 15 17 19
Year Number
An
nu
al d
aily
peak d
isch
arg
e
(cu
mecs)
Control ScenarioSubbasin 23
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
1 3 5 7 9 11 13 15 17 19
Year Number
An
nu
al d
aily
peak d
isch
arg
e
(cu
mecs)
GHG ScenarioSubbasin 23
Events exceeding arbitrary thresholds in Ganga River Basin
Discharge (cumecs)
Control GHG Control GHG
Ganga Subbasins Sub11 Sub11 Sub23 Sub23
Discharge>10000
>20000
6 7
1 5
Discharge>12000
>30000
1 6
0 2
Flow Duration Curve for Ganga River for Control and GHG scenarios
0.00001
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
100000
0 10 20 30 40 50 60 70 80 90 100
% of time flow equal or exceededF
low
(C
um
ec
s)
ControlGHG
Ganga River - Flow Duration Curve
Dependa
ble Flow
(cumecs)
25% 50% 75% 90%
Control 4648 716 12.88 0.4394
GHG
Scenario
3649 754.5 50.5 5.323
Future Work Required
� Incorporation of the data on glaciers
� Mapping and incorporation of present manmade interventions
� Generation of coping strategies and scenarios
� Quantifying the uncertainties of the predictions
Thank you