1. Department of Geosciences, Auburn University, Auburn, AL 36849, USA
Comparison of Managed Aquifer Recharge Test Sites for Characterization of Designs for Optimal Performances in southwest Bangladesh
Mustuque Ahmed Munim
Department of Geosciences, Auburn University, Auburn, AL 36849, USA
ABSTRACT
METHODS A
Access to safe drinking water in south-western part of Bangladesh is very low due to the surface water salinity problem and recurring storm surges. Peoples living in this region usually rely mostly on pond and rainwater availability of which depend on time of the year and cyclonic storm surges can make things worse. Managed aquifer recharge (MAR) has been proven as an option in different countries of the world to reduce salinity by means of diverting roof-top rain or pond water in shallow brackish aquifers through injection well. The outcome of the research provides the guideline for applicability of MAR to improve water access in the coastal areas. The successful implementation of the technique might bring about “the solution” of drinking water problems of the coastal areas of Bangladesh. B C
INTRODUCTION D
Fig. 2.3 Design of an infiltration well.
The southwestern coastal districts Bagerhat, Khulna and Satkhira of Bangladesh has limited access to safe drinking water mostly due to salinity in surface and groundwater (Ahmed et al, 2009; DPHE & BGS, 2001). Rural communities collect rain water for drinking and cooking during the monsoonal wet season. For the dry season, they use pond water which is being threatened by inundation caused by storm surges related to cyclones such as SIDR and AILA, and by loss of fresh water pond when it is converted to brackish water for shrimp aquaculture (Ahmed et al, 2009). Managed Aquifer Recharge (MAR) is the purposeful recharge of water to aquifers for subsequent recovery or environmental benefit achieved through injection wells, infiltration basins and galleries for rainwater, storm water, reclaimed
water, mains water and water from other aquifers that is subsequently recovered for
all types of uses.
Acknowledgements
Fig. 2.5 Civil construction (A), arial view of the over ground MAR system (B),
installation of piezometers (C), and arial view of Assasuni site after construction (D).
Fig. 2.2 Schematic diagram of pond pumped + rooftop rain water infiltration system, Assasuni, southwest Bangladesh.
Fig. 2.4 Filtration system.
RESULTS
Fig 1.2 Schematic diagram of Managed aquifer recharge through infiltration.
Fig. 3.1 Comparison of rate of infiltration of all over ground and underground MAR sites.
Fig. 1.1 Location of 20 Managed Aquifer recharge sites in three coastal districts (Bagerhat, Khulna and Satkhira).
Fig. 1.3 Available water sources in the study area (left pond sand filter and right rainwater harvesting).
Methods
Fig. 3.2 The depiction of litholog of Assasuni and Chandipur MAR site.
Fig. 3.4 Comparison of the rates of infiltration of the Assasuni and the Chandipur MAR sites.
CONCLUSION
REFERENCES
Ahmed, K.M., Sultana, S., Hasan, K., Groen, K., Tuinhof, A., Spruijt, H., Patra, L., Ghosh, S.K., Huq, I. (2009): Artificial Recharge to Manage Groundwater Quantity and Quality in Bangladesh: GIS Mapping and other Investigations, Alternative Recharge Systems, ISMAR7, Abu Dhabi, UAE, 2010, P.1.
Ahmed, K.M., Sultana, S., Mahtah-Ul-Alam, S.M., (2012): Action Research on Groundwater Buffering in Bangladesh, Construction Completion Report on 12 MAR Test Sites. Department of Geology, University of Dhaka, p
Rates of infiltration of 20 MAR sites analyzed and two MAR site has been selected from their higher and lower rate.
Site specific well design has been performed and construction has been carried out using locally available materials and drillers.
A total of m³ and m³ of water has been injected in Assasuni and Chandipur respectively.
Assasuni aquifer contains medium sized, well sorted grains whereas Chandipur site contains finer moderate sorted grains with clay intercalation and clay lenses.
Continuous operation, effective management and maintenance is required to enhance the rate of infiltration.
This technology can be applied in the other coastal areas of the country.
ACKNOWLEDGEMENTS
Fig. 2.1 Flow diagram showing the major steps of the study.