Spatial and Temporal Analysis of Groundwater Level Fluctuation in Dhaka City, Bangladesh

摘要

This study was conducted to determine the present status of groundwater level in Dhaka city. During 2005, about 1.6 Mm~3 day~(-1) of groundwater was withdrawn by Dhaka Water Supply and Sewerage Authority (DWASA) against the city's total demand of 2.1 Mm~3 day~(-1). Compared to the exploitation of groundwater, the recharge to aquifer is very negligible as the geological settings and urbanization has retarded both the vertical and horizontal recharges. Consequently, groundwater table is continuously declining at an average rate of 2m year~(-1) since, 1986. Continuous groundwater mining has caused the dry season water table to move downward from -54 to -45 m depth from the sea level. The severe decline of groundwater level was observed in the central part of the city, compare to the river periphery, creating a cone of depression. If this falling trend of the groundwater level continues that might create an increased pressure on water storage and may invite land subsidence or other environmental hazards. So, the aquifer requires sustainable management to protect future water quality and to ensure that the resource can continue to meet the quantitative demands being placed upon it.