Ground Water Pumping And Its Impact
On Dhaka City
Dhaka as the capital of Bangladesh has grown into a
busy city of about ten million people. Having a sweet blending of the old and
new architectural trends, Dhaka has been developing fast as a modern city since
independence in 1971 and is throbbing with multidimensional activities, be it
industrial, commercial or political. Area of Dhaka is 303 sq. km. (approx.).
Water has primarily two major sources. They are ground water and surface water. DWASA is primarily responsible for the supply for all domestic and commercial water to the city dwellers. Besides this many private organizations have their own deep tube wells to abstract ground water for their own uses. The water supply system of Dhaka city is dependent on mainly ground water source. Around 97% supply of DWASA comes from ground water and only 3% comes from surface water. At present DWASA are operating 287 plus deep tube wells in its service areas and is able to supply the city dwellers only about 60 percent of their total water demand. Although DWASA has surface water based water treatment plant at Saidabad, which will be operative very soon, but an appreciable amount of total water demand would be mitigated from the ground water source due to the various limitations of the surface water source.
Dhaka’s present population is 10 million and total
water demand 1600 million liter per day (mld). This water demand is increasing
at a rate of 11% each year. This is due to the rapid population growth in the
Dhaka city. Dhaka is now growing in a very unplanned way, so a large number of
high-rise buildings has been constructed in some areas like Motijheel,
Panthapath, Mohakhali areas of Dhaka city. The high-rise building creates local
pressure on DWASA distribution system. To meet the future water demand more
ground water will require to be pumped by deep tube wells.
The most important problems related to the
ground water abstraction in Dhaka city are as follows:
1. If the water is continued to be withdrawn at
the present rate, then the total draw down will cause many of existing DWASA
tube wells inoperative in future.
2. Degradation of ground water quality.
3. Ground water with drawl can lead to accelerated consolidation of sub-surface material and hence increase subsidence. The land subsidence then may manage public and government buildings, roads, bridges, and railways, swear system and water distribution system.