Presented at the International Conference on Regional Cooperation on Transboundary Rivers – Impact of the Indian River-linking Project" (ICRCTR) At Osmani Memorial Hall (OMH), Dhaka, Bangladesh, 17-19 Dec 2004

PROPOSED INDIAN RIVER-LINKING PROJECT AND WATER RESOURCES MANAGEMENT

IN BANGLADESH

1

Prof. R. Jagadiswara Rao, Ph.D.Department of Geology,

Sri Venkateswara University Tirupati, AP 517502, India

Email: rjagadiswara@gmail.com

WATER PROBLEMS OF BANGLADESH

• A third of the country suffers from floods in monsoon.

• Half of the cultivated land is rain-dependent.

• Severe water shortages are felt in lean season.

2

• Most surface water is biologically polluted.

• High-arsenic drinking water made over one fifth of population to suffer from arsenicosis & one thirtieth from lifetime skin cancer.

• Use of high-arsenic groundwater for irrigation has increased the arsenic levels of foods.

PROPOSED INDIAN RIVER LINKING PROJECT

• The 2002-drought had brought a virtual water war between Karnataka and Tamil Nadu states in sharing the Cauvery river waters of south India.

• The Supreme Court of India has directed the Indian government to transfer surplus waters of the GBM basin

3

government to transfer surplus waters of the GBM basin to south India within a timeframe to prevent future wars.

• The government has constituted a task force to fulfill the Supreme Court directive.

• This created panic in Bangladesh for an impending water crisis of a severe magnitude.

WATER CRISIS IN GANGES RIVER

• India had built Farakka barrage in 1974 to increase the lean-season flow of the Hoogly River and make Kolkata an all-weather port.

• This had reduced the lean-season flow of the Padma River causing water crisis in Bangladesh.

4

• India had entered into a treaty with Bangladesh in 1996 to restore the flows of the Padma River.

• The very purpose for which the Farakka barrage was constructed was defeated.

• India finds transfer of Brahmaputra waters to the Ganges and other southern rivers as the only alternative.

MYTH OF SURPLUS WATER IN BRAHMAPUTRA BASIN

Brahmaputra River Basin Rank

Mean Surface Runoff (cu km/year) 586 1

Per Capita Water Availability (cu m/year) 16,000 1

Mean Utilisable Surface Runoff 24 7

Per Capita Water Availability (cu m/year) 680 10

5

Per Capita Water Availability (cu m/year) 680 10

Live Reservoir Storage Created (cu km) 1.1 12

Net Area Cultivated North-East States Punjab

% Rain-Dependent Cultivation 61 4.5

% Irrigated by Major Irrigation Works 11 31

% Irrigated by Minor Irrigation Works 7 0.5

% Irrigated by Groundwater 21 64

GROUNDWATER IN BANGLADESH

GBM Basin Ganges

Basin Brahmaputra

Basin

6

Static Groundwater Reserve (cu km) 7,834 1,019

Dynamic Groundwater (cu km/year) 171 27

Balance Groundwater Joining Sea (cu km/year) 101 23

GROUNDWATER PROBLEMS OF BANGLADESH

• The rosy hopes that all the water needs of the country could be met through intensive use of groundwater were shattered with the discovery that the Holocene aquifers carry high-arsenic groundwater harmful both for drinking and irrigation.

• The best option to tackle the arsenic problem consists in using surface water and shallow groundwater of Recent Age

7

using surface water and shallow groundwater of Recent Age for drinking and irrigation.

• The problems associated with this option include: - Water shortages in the lean season, - Biological contamination of surface water and - Increase of arsenic levels of shallow wells from underlying

Holocene aquifer in course of time.

SOURCES OF DRINKING WATER IN BANGLADESH (M.F. Ahmed, 2002)

%

Protected Water Supplies by Pipes 10

Shallow Tube Wells 80

8

Hand-Operated Deep Tube Wells 6

Special Methods to Supply Low-Arsenic Water 4

Present Population Drinking High-Arsenic Water 22

Present Population with Lifetime Skin Cancer 0.3

Population Drinking High-Arsenic Water in Near Future 70

PREVENTION OF GROUNDWATER JOINING SEA THROUGH SUBSURFACE DAMS

• On the assumption that the K of the sandy alluvium is 30 m/day, the quantum of groundwater younger to Holocene Period in hydraulic connection with surface water getting lost into the sea from a 300-km wide and 10-m thick sandy alluvium along the Bangladesh coast is estimated at around 33 cu km a year.

9

10-m thick sandy alluvium along the Bangladesh coast is estimated at around 33 cu km a year.

• By arresting a good portion of this groundwater through construction of subsurface dams across major and minor rivers, the entire irrigation, drinking and other needs of the country could be met on a sustainable basis without the need to pump any deeper groundwater.

10Arrest of Groundwater by a Subsurface Dam (After J-Green, 2003)

ENVIRONMENTAL IMPACT OF A NATURAL SUBSURFACE DAM

• Unlike a surface dam or barrage that obstructs surface runoff to cause adverse environmental effects, a subsurface dam arrests only groundwater flowing slowly throughout the year.

• The best example of a natural subsurface dam across a dry stream underlain by sand becoming perennial, while passing through a

11

underlain by sand becoming perennial, while passing through a gorge, is seen in the Pennar basin of south India.

• This is because of the limited groundwater in sand getting obstructed by rock both in the bottom and sides to emerge as base flow.

• Historic records indicate that the habitation in the gorge was flourishing since several centuries and thus testify absence of any adverse environmental effects.

12

Perennial Portion of Gandi Gorge of the Papaghni River in the Pennar Basin of South India

13

Diagram Showing How an Ephemeral Stream Becomes Perennial while Passing through a Gorge

SURFACE DAM/BARRAGE VERSUS SUBSURFACE DAM

• A surface dam or barrage obstructs flood runoff to produce adverse environmental effects such as, land submergence, flood aggravation, sedimentation, high evaporation losses, high seismicity and even dam breach.

• On the contrary, a subsurface dam only arrests groundwater

14

• On the contrary, a subsurface dam only arrests groundwater flowing slowly throughout the year to emerge as base flow without producing any adverse environmental effects.

• For example, had a subsurface dam was constructed instead of barrage at Farakka, the enormous groundwater flowing beneath the Ganges would have emerged as large base flow to the prosperity of both India and Bangladesh in a big way.

15

Diagram Showing the Differences Between a Surface Dam/Barrage and a Subsurface Dam Across a River

EXAMPLES OF SUCCESSFUL SUBSURFACE DAMS

Examples of successful subsurface dams come from India, Africa and Japan.

• Somasila surface dam-cum-subsurface dam has one of the biggest subsurface dams in south India, constructed to prevent groundwater seepage of over 0.5 cu km a year.

16

• The work of Japan Green Resources Agency (J-Green) since 1988 in some Japanese islands has proved that subsurface dams provide water security for drinking and irrigation in an environmentally friendly way.

• J-Green has been now using their technical know-how in Indonesia, China and Mexico through active support by the Japanese Government and the Japan International Cooperation Agency (JICA).

SATELLITE PICTURE OF SOMASILA SUBSURFACE DAM -CUM-SURFACE DAM

17

HOW TO OBTAIN LOW-ARSENIC GROUNDWATER?

• Recent sandy alluvium, hydraulically connected with rivers but separated from the underlying Holocene aquifer by an aquiclude, can discharge large quantities of groundwater free of both arsenic and bacteria through proper well design.

• My work in conducting detailed scientific studies including test boring studies at close intervals allowed to provide certain

18

boring studies at close intervals allowed to provide certain diagnostic tools to determine accurately the junction between the top aquifer and the top of the aquiclude separating the underlying high-iron aquifer.

• Well sites are pinpointed at sites where sand of high hydraulic conductivity extends to maximum depth.

• The same methodology can be used to obtain arsenic-free groundwater of high discharge from shallow wells in Bangladesh.

SITE SELECTION OF A WELL WELL CARRYING ARSENIC-FREE GROUNDWATER

19

Results of boring studies and mechanical analysis o f test bore samples to pinpoint a site for well that carries arsenic-free groundwater. The site ‘A’ where sand with high hydraulic conductivity extends to maximum depth is selected for the construction of a high-yielding shallow sanitary well.

20DESIGN OF A SHALLOW SANITARY WELL THAT DISCHARGES L ARGE QUANTITIES OF WATER FREE OF BACTERIA AND ARSENIC

CONCLUSIONS

• The utilisable surface runoff and live storage in the Brahmaputra basin are so meagre that it is technically not feasible to transfer any water from the basin even to the Ganges river.

• The best way Bangladesh could get rid of the arsenic menace is by stop using groundwater in the Holocene and older aquifers.

21

• The best way Bangladesh could have enough arsenic-free water throughout the year is through construction of subsurface dams all along the coast to prevent the large quantum of shallow groundwater joining the sea throughout the year.

• Pinpointing well sites through detailed scientific studies including boring surveys and mechanical analysis of test bore samples, shallow wells of proper design can discharge arsenic-free water in large amounts without ever turning arsenic-rich.

Thank you

22

Thank you