H51K-1540
Pressures on Dupi-tila Aquifer of Dhaka City and Possible Response Action
Friday, 18 December 2015
Poster Hall (Moscone South)
ABM Firoz1, Laura Foglia2, Andres Marandi3, Md. Bayzidul Islam4, Lars Ribbe4 and Christoph Schueth5, (1)Researcher, Institute for Technology and Resources Management (ITT), Cologne, Germany, (2)Darmstadt University of Technology, Darmstadt, Germany, (3)Technical University Darmstadt (TUD), Institute of Applied Geoscience (IAG), Darmstadt, Germany, (4)Technische Hochschule Köln (TH Köln), Institute for Technology and Resources Management in the Tropics and Subtropics (ITT), Cologne, Germany, (5)Darmstadt University of Technology, Institute of Applied Geosciences, Darmstadt, Germany
Abstract:
Dhaka is a large growing megacity that depends on groundwater for mostly all kind of water needs. Consequently, overwhelming abstraction of groundwater has been causing a linear to exponential drop in groundwater level and substantial aquifer dewatering of the Dupi-Tila aquifer of Dhaka basin. Total water demand in Dhaka city varies from 2100 to 2300 Million Cubic Meter per Day (MCMD) with seasonal variation for a population of about 16 million. Analysis reveals that upper parts of the aquifer are already dewatered throughout the area, and the water level has dropped to 30 m below sea level in the south central part of the city, where the ground surface elevation is 5.7 m. Natural retention area and natural drainage areas are hindering by the unplanned and haphazard vertical and horizontal growth of the city which is ultimately fragmenting infiltration and aquifer recharge. This study uses MODFLOW-2005 to simulate three-dimensional, steady-state groundwater flow, while the inverse modeling approach of UCODE_2005 has been used for parameter estimation and uncertainty analysis. Furthermore, a through hydrogeological model has been constructed from 150 borehole lithological information for geological characterization of the aquifers. This study stresses the importance of the total water balance of the study area and how recharge and water pumping affect the total water balance. The calibrated model results exhibit the total water abstraction is about 2302 MCMD. The model results further reveals that, there is extreme decline of groundwater level in the extent of -37 meters below the mean sea level at the inner core of the city area and the trend of declining remains same over the years. The surrounding rivers play an important role to balance the water budget and there is stable connection between the rivers and aquifer. The outcome of the research will contribute to develop a rational and sustainable management approach for the groundwater resources management in future.
