Abstract:
The present water supply system of Dhaka depends mostly on groundwater. The existing
facilities of DWASA cannot keep pace with growing demand of safe water supply. This
study investigates the adequacy of current ground water supply system in Dhaka city
following standard pump head-flow characteristics. The degree of inadequacy is also
investigated for considering upgradation of current system if possible or generation of
alternate sources where necessary. A groundwater model has been developed to
understand the groundwater flow dynamics and to assess the groundwater resources at the
present condition as well as groundwater resources at future development scenarios
For the static Pump adequacy study, water supply and distribution network has been
generated based on road network map. Network coverage area served by this distribution
system has been calculated using GIS. A groundwater model has been developed, the
major components of which include evapo-transpiration, unsaturated zone, saturated
zone, overland flow and river systems. Technical options/alternatives have been
investigated to address the study objectives and finally to make comprehensive water
management plans for the study area
From the study, existing pump system has been found to be sufficient upto 2015 for
Hazaribag, Tejgaon, Ramna, and Mohammadpur with adequate supply and pressure. For
Gulshan, Motijheel and Dhanmondi existing system can meet the demand reducing the
pump head from 70m to 60m and thereby reducing the system pressure as well. Surface
water may be utilized which will improve pressure head. The existing pump systems
can’t meet the demand of Shyampur, Sabujbag, Mirpur.
From the hydrograph analysis in Mike SHE it is found that Mirpur, Tejgaon and Gulshan
are highly vulnerable to aquifer dewatering. The hydrographs estimate that the water
table may lower more than 70 meter within 2015 in this areas if this trend continues. According to the analysis in Mike SHE Pheratic surface lowers as much as 60 meter
before monsoon and as much as 32 meter after monsoon. Mirpur, Hazaribag, Dhanmondi
area has been suffering from the lowest contours of water table.
Considering Pump adequacy and model simulation, it can be said that the domestic water
supply system comprising mostly of ground water cannot keep pace with growing
demand of safe water in Dhaka. The water table as well as current groundwater
abstraction is also not sustainable. Therefore, this study is expected to provide a
systematic and effective guideline for the analysis of Pump adequacy behavior within the
study area for current and future conditions for considering upgradation of current system
if possible or generation of alternate sources where necessary.
