ISMAR7 Abstract

Action Research for Managed Aquifer Recharge in Bangladesh to secure Groundwater Quantity and Quality

K M Ahmed1*, K Hasan1, S Sultana1, K Groen2, A Tuinhof2, H Spruijt3, L Patra3, S K Ghosh4, I Huq4
1 Department of Geology, University of Dhaka, Curzon Hall Campus, Dhaka 1000, Bangladesh
2 Acacia Water, Jan van Beaumontstraat 1, 2805 RN Gouda, The Netherlands
3 UNICEF Bangladesh, BSL Office Complex, 1 Minto Road, Ramna, Dhaka 1000, Bangladesh
4 Department of Public Health Engineering, DPHE Bhaban, Kakrial, Dhaka 1000, Bangladesh

* Corresponding Author (kmamed@univdhaka.edu, kazimatin@yahoo.com)

Abstract
Bangladesh depends heavily on groundwater for water supply and for irrigation. The country’s major achievement in providing access to safe water and attaining self sufficiency in rice production was made possible due to use of groundwater. The intensive groundwater use along with climate change impacts have induced a number of constraints, resulting in increasing seasonal water shortage in parts of the country. Heavy withdrawals for irrigation and municipal water supplies cause water level to decline in areas like the Barind Tract and Dhaka City.  Increase of groundwater salinity in the coastal region hinders supply for drinking and other uses. High arsenic levels in shallow groundwater (often combined with high iron or manganese) is a another major concern. In some areas, like in the Jessore region, both shallow and deep groundwaters are contaminated with arsenic and access to safe water has reduced significantly. Artificial recharge with rainwater and surface water can help in managing the constraints and increase access in the areas with severe shortage, particularly in dry season.

An action research program has been undertaken to assess the potential for rainwater harvesting and recharge as a means of groundwater buffering. Relevant data has been collected to produce a series of GIS map to identify areas where groundwater buffering is necessary and feasible. Various GIS layers have been created and overlapped to identify critical areas such as water level deeper than 7.5m, high salinity in shallow groundwater, and arsenic in shallow and deep aquifers.  The areas with shallow groundwater salinity were given priority for further testing under the current phase 1 and 2 of the program.

Field investigations have been conducted in the Khulna region, including shallow exploratory drilling, water level observations, water sapling and testing, vertical electrical sounding, and field verification of features such as water bodies and roofs. The results have been unutilized to design a recharge technology testing program in the forthcoming rainy season (June-October 2010) to test the recharge of fresh water in the shallow brackish groundwater aquifer underneath a top clay layer.  Both the recharge rates and hydro-chemical process will be investigated in 4 test sites.

A 2D and 3D simulation model have been developed to assess the infiltration capacity in shallow aquifers under varying conditions. The results of the technology testing will be used to calibrate the models for the design of real scale pilot projects to be implemented din 2011.