hydrology and water resources of the indo-gangetic basin
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G K Ambili
IWMI, New Delhi
Hydrology and Water Resources of Indo-Gangetic basin
Surface water resources
Surface water resources
Surface water availability
Indus
•Average annual flow 226 BCM•Monsoon season- 80%
Ganges
•Average annual flow 424 BCM
Indian IGB – 598 BCM, 88% in Ganges basin
Average annual discharge of Indus tributaries
Average annual discharge of Ganges tributaries
Hydrologic components
• Precipitation– Altitudinal and seasonal variability
Indus- most of precipitation altitudes b/w 2500 m and 6000 m
Average annual precipitation
in Pak-Indus: 205 mm
in India-Indus: 200-1600 cm
Ganges - >70% from South-west monsoon
Annual precipitation increases eastward, 350 mm in west to 1500mm in delta region
Indus:
upper and north-eastern region ET01200-1300 mm
Lower, Southern Punjab and Sindh ET0 1700 – 2100 mm
Hydrologic components
Evapotranspiration
Ganges
among the sub-basins, Karnali has highest evaporation
1833 mm/yr
Mean annual RunoffIndus – 100-1500 mmGanges - 174 mm – 976 mm
Resource Utilization –Irrigation water use
Major irrigation projects• Indus Basin Irrigation system
Irrigating 17 Mha
130 BCM of water, 75% of annual flows in Indus
•Bhakra-Nangal Project
Irrigating 1.46 Mha
design duty at head 0.19 l/s/ha
Major irrigation projects-Ganges
• Sarda scheme, UP
CCA 2.55 Mha
• Sone scheme, South west Bihar
CCA 0.21 Mha
• Gandak scheme, North Bihar & Nepal
CCA1.76 Mha
• Ganges-Kobadak (G.K Project), Bangladesh
CCA 1.98 Mha
1.25
18.67
0.8
1.76
Pakistan
Indian-IGB
Nepal
Bangladesh
Domestic water use, BCM
126
93
105
38.0
51.3
89.3
1.6
5.1
6.7
36.4
46.2
82.6
30.2
55.1
85.3
Indus basin
India
Pakistan*
Total
TotalDomestic, Industrial & others
Irrigation
61
10
45
54
102.4
1.1
29.3
132.8
8.2
0.3
4.1
12.6
94.4
0.8
25.2
120.4
168.7
11.5
64.6
244.8
Ganga basin
India
Nepal
Bangladesh
Total
Stage of GW
Development (%)
Annual Groundwater Draft (BCM)Groundwater
Available
(BCM)
Basin
Groundwater Resources
* It is assumed that 90% of groundwater use is consumed by irrigation sector
Groundwater availability and use
Tube-well development in Pakistan
0
100
200
300
400
500
600
1960 1970 1980 1990 2000
Year
No
. o
f tu
bew
ells, x1000
91
92
93
94
95
96
97
98
99
100
Pri
vate
ow
ned
wells, %
of
tota
l
No. of tubewells
Private-owned
Salinity Control and Reclamation Project (SCARP)
0
100000
200000
300000
400000
500000
600000
700000
800000
900000
1987
-88
1988
-89
1989
-90
1990
-91
1991
-92
1992
-93
1993
-94
1994
-95
1995
-96
1996
-97
1997
-98
1998
-99
1999
-200
020
00-2
001
Year
Sh
allo
w T
W
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
Deep
TW
STW
DTW
Tube-well Growth in Indian IG Basin
Change (%)
2000-011993-94Change (%)
2000-01
1993-94
+25
+18
+42.9
+63
+25.8
21,760
10,340
200
3,462
35,762
17,413
8,760
140
2,124
28,437
-29.4
-11.8
-14.8
-10.7
-24.2
11,035
3,740
1,960
480
17,215
15,633
4,240
2,300
537
22,709
Key Indian states*
Pakistan Punjab
Sindh
Bangladesh
All areas
Net irrigated area served by GW
Net irrigated area under surface irrigation
Changing profile of irrigation in South Asia
*Andhra Pradesh, Arunachal Pradesh, Assam, Bihar and Jharkhand, Goa, Himachal Pradesh, Madhya Pradesh and Chhattisgarh, Orissa, Punjab,
Rajasthan, Uttar Pradesh and Uttaranchal, West Bengal
Source: Shah et al., 2008
Water related issues
Surface water
•Inefficient surface water utilization in Gangetic basin
Improvement of infrastructure to store high runoff in eastern Gangetic basin
solution to flooding problems
Need to promote conjunctive use
• Increasing stress on the resource from domestic and industrial sector
in urban areas of Gangetic basin
Flexible water allocation rules??
Strategies to combat reduced water availability for irrigation-
whether water available will be enough to meet the food needs?
Accessibility of rural poor, livelihood concerns.
Consideration of environmental water requirements at reduced water availability in future.
• Prone to extreme climatic events, intensified by climate change
•Shift in hydrologic cycles
further aggravate competition among sectors in urban sector
Shift in course of river
decrease GW recharge – Western IGB
• Degradation of surface water quality in Ganges
•Improved sanitation, sewage network in urban cities
•Polluters pay principle
Groundwater
• Over-exploitation of dynamic GW resources and resultant water table decline
Conjunctive use?
GW recharge measures to improve water table levels
Appropriate energy sector policies- rationalized tariff
• Degradation of GW quality
Arsenic contamination
Flouride contamination in West Bengal and Haryana
High concentrations of iron and Mn in Bangladesh
• Water logging and secondary salinization
– Saline GW use- impacts on livestock water productivity
esp. in Haryana and Punjab
– Socio-economic impacts
Salinity management measures
• Crop management, nutrient management, water management
• Groundwater development in eastern IGB
Improving rural electrification, low cost pumping technologies
Suitable market mechanisms
Bhakra-Nangal Project
Climate change impacts- Extreme events
51 Mha drought prone area in India
2002, Gangetic states, damages of 910 Million US$
Pakistan 1998-2002, surface water availability reduced by 30%
Total estimated damages – 45000 million US$
Glacial Lake outburst floods (GLOF)
Eastern Gangetic plains-once in 2 years
Bangladesh – every year
DroughtsFloods
Plot of Qmaf vs. Qb in Gangetic plains
Surface water quality
Indus- relatively good for agriculture use
•Length of river for BOD>6 mg/l (severely polluted): 70 km (1.7%)
•Length of river for BOD 3-6 mg/l (moderately polluted): 132 km (3.2%)
• Length of river for BOD< 3 mg/l (relatively clean): 3917 km (95.1%)
Ganges- highly polluted, sewage and industrial wastewater
•Length of river for BOD>6 mg/l (severely polluted): 1760 km (13.87%)
•Length of river for BOD 3-6 mg/l (moderately polluted): 3612 km (28.46%)
•Length of river for BOD< 3 mg/l (relatively clean): 7318 km (57.67%)
Surface water quality
Water table decline
Punjab and Haryana – upto 1m/yr
In UP: Over-exploited and critical blocks – 30 to 50 cm/yr
Madhya Pradesh: Fall upto 4 m observed in certain pockets
GW Over-extraction
• High concentrations of Iron and Manganese in GW in Bangladesh
• High flouride concentrations in Haryana
• Salinity- Irrigation induced, in Haryana, Punjab
Groundwater quality
Increase in energy cost with declining GW levels, Rachna Doab
Gross Areas Where Arsenic-Polluted Groundwater Has Been Reported
Arsenic concentrations recorded
510 ppb in Bangladesh
1,891 ppb in Bihar
2,629 ppb in Nepal
Groundwater quality
Groundwater quality
Arsenic concentrations in GW in Bangladesh
TotalDomesticIrrigation
39.00
20.00
170.00
109.00
30.00
14.00
21.00
48.00
145.00
125.00
70.00
66.00
42.00
10.77
2.80
0.48
9.45
0.12
0.33
1.09
17.12
31.16
12.99
48.78
1.39
11.65
1.37
0.48
0.28
0.35
0.02
0.24
0.38
1.04
0.83
1.39
3.42
0.05
0.81
9.39
2.31
0.20
9.10
0.09
0.10
0.70
16.08
30.34
11.60
45.36
1.34
10.84
Bihar
Chattisgarh
Delhi
Haryana
Himachal Pradesh
Jammu&Kashmir
Jharkhand
Madhya Pradesh
Punjab
Rajasthan
Uttar Pradesh
Uttaranchal
West Bengal
Stage of GW development
Annual GW draftState
Spatial variability of ET0 in IBIS
(a)(b)
Kharif Rabi
289
174
351
573
594
737
972
976
778
Mean annual runoff (mm)
809
871
1138
1073
1308
2570
1241
1265
1670
Precipitation (mm)
520
697
787
500
714
1833
269
289
892
Yamuna
Chambal
Betwa
Ramganga
Sone
Kamali
Gandak
Bagmati
Kosi
Evaporation (mm)
Sub-basin
Mean annual runoff in Indus and tributaries
43.294.5247.8014.1533.68Total
0.02
8.63
0.39
2.43
21.44
10.38
Net groundwater availabilityTotal
rechargeNon-monsoon
Monsoon
0.02
0.68
0.04
0.27
2.33
1.18
0.023
9.31
0.43
2.70
23.78
11.56
0.006
3.64
0.10
1.32
6.90
2.18
0.017
5.67
0.34
1.38
16.89
9.38
Chandigarh
Haryana
Himachal Pradesh
Jammu&Kashmir
Punjab
Rajasthan
Net discharge
Annual replenishable groundwater resources
State
181.714.47196.1751.85144.34Total
27.42
13.68
0.28
5.25
35.33
70.18
2.1
27.46
Net groundwater availabilityTotal
rechargeNon-monsoon
Monsoon
1.77
1.25
0.02
0.33
1.86
6.17
0.17
2.9
29.19
14.93
0.3
5.58
37.19
76.35
2.27
30.36
5.78
2.43
0.11
1.18
5.64
25.78
0.63
10.3
23.41
12.51
0.19
4.4
31.55
50.58
1.64
20.06
Bihar
Chattisgarh
Delhi
Jharkhand
Madhya Pradesh
Uttar Pradesh
Uttaranchal
West Bengal
Net discharge
Annual replenishable groundwater resources
State
Parameters Punjab Sindh NWFP Baluchistan
Recharge Components
Rainfall recharge 12.02 2.38 1.06 1.47
Recharge from canal system 26.34 8.21 1.21 0.35
Return flow from irrigation 8.60 10.42 1.24 0.45
Domestic and industrial return flows 0.69 - - -
Other return flows - 0.96 0.16 0.10
Recharge from rivers 4.25 0.36 0.16 0.22
Total 51.90 22.33 3.82 2.59
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