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