Dhaka, Bangladesh Vulnerability and sustainability of the Dhaka groundwater resource William Burgess, Kamrul Hasan, Emma Rihani, Mohammad Hoque Kazi Matin Ahmed, Dhaka University George Darling, BGS Dhaka, Bangladesh Vulnerability and sustainability of the Dhaka groundwater resource 15 million inhabitants 85% water demand supplied from groundwater 250 DWASA boreholes distributed throughout the city DWASA Pumping >300 Ml/d Unregulated peri-urban slum hand-pumped tubewells Unsustainable abstraction - declining water levels, 1 m/year - vulnerable to quality deterioration from induced river recharge rather than urban sources of contamination NASA Chadnighat river water treatment works 1874 DPHE borehole 1949 Dhaka WASA established 1963 Bangladesh independence 1971 220 water supply boreholes, Dhaka aquifer 1990s The Chadnighat water works: 5% of water supply to Dhaka 23.6800 1999 90.3400 90.3900 90.4400 Longitude 90.4900 23.7300 23.7800 Latitude 23.8300 23.8800 SW NE Induced recharge through R.Buriganga DHAKA METROPOLITAN AREA Bashabo Holocene sands Madhupur Clay Dupi Tila Pliocene sand aquifer Dhaka: Municipal waste disposal in flooded depression Dhaka: Municipal waste disposal in flooded depression Tannery solvents: PCE, TCE Dhaka: unregulated industry, contaminated land and effluents Industrial effluent + raw sewage draining to River Buriganga Low quality water invades the aquifer in the south: 23.7800 as vertical seepage from industrial areas ? 23.7300 or from the polluted River Buriganga? 23.6800 Latitude 23.8300 23.8800 Dhaka: groundwater EC, 1999 1999 90.3400 90.3900 90.4400 Longitude 90.4900 23.6800 1999 90.3400 90.3900 90.4400 Longitude 90.4900 23.7300 23.7800 Latitude 23.8300 23.8800 -20 Baseline groundwater away from Dhaka -30 W Works tubewell 2 H‰ -25 -35 JN Coll. tubewell -40 -45 -7 -6 -5 O‰ 18 -4 -3 The vulnerability of the Dhaka DWASA aquifer • Groundwater quality variation demonstrates aquifer vulnerability • Induced river recharge pollutes aquifer in SW Dhaka • Abstraction boreholes protect central urban area • Organic contamination identified from industrial zones? • Urban recharge a longer term threat Shallow groundwater – vulnerable hand-pumped supplies The vulnerability of the Dupi Tila aquifer of Dhaka Recommendations Monitor groundwater levels, groundwater quality surface water quality, industrial discharges city wide shallow-deep +DWASA boreholes Environmental legislation prioritise industrial discharges & river quality The future extend distributed supplies, centralise treatment protect urban groundwater as a strategic resource develop peri-urban well-fields+treatment plants The London Basin aquifer – over-abstraction, and water level rebound The London Basin aquifer – over-abstraction, and water level rebound Groundwater dependent megacities for individual cities see http://www.iahorg/commwg.htm New York, Los Angeles, Mexico City, Lima, Santiago, Buenos Aires, Rio de Janeiro, Sao Paolo, Bogota, Tokyo, Osaka, Hong Kong, Manilla, Jakarta, Beijing, Bombay, Madra, Bangalore, Hydrabad, Dhaka, Karachi, Lahore, Delhi, Tehran, Cairo,… (London, Birmingham, Liverpool, Nottingham …) Dhaka, Bangladesh Vulnerability and sustainability of the Dhaka groundwater resource William Burgess, Kamrul Hasan, Emma Rihani, Mohammad Hoque Kazimatin Ahmed, Dhaka University and George Darling, BGS Geological map of Bangladesh Water sources for urban populations: the options • Local surface water London • Imported surface water Manchester Calcutta • Treated foul water Windhoek • Desalinated water Dubai • Groundwater → local → imported Dhaka Sanaa Groundwater – cheaper to develop, in stages, generally good quality, less vulnerable, less treatment Vulnerability of urban groundwater Over abstraction → declining water levels declining efficiency increasing costs shallow aquifer dewatering modified recharge Contamination → unsewered sanitation landfills industrial discharges contaminated land contaminated surface water saline water