Md. Firoj Alam
Water table recharges through a natural process. It occurs as rain and surface water percolates down through the natural filter constitute of fine-grained soil to join with the ground water on an impervious layer. When a balance between this recharging and extraction is maintained, the ground water aquifer remains static. But it falls down when the extraction rate become higher than the rate of recharging. We can understand it only when our tube-wells cannot reach to the ground water level and fail to discharge any water. Desertification is the ultimate affect of the water table depletion. As we are predominantly depended on the ground water for our domestic, agricultural, and industrial use, we face water scarcity if the ground water table is depleted.
The ground water table of Dhaka city is falling down at an alarming rate. In last six years, the water aquifer of this city has gone at least 20 meters down: 3.3 meters per year. No doubt that the increasing gap between extraction and recharging is dipping the water level down.
The water table of this city is falling down because of withdrawing excessive water without keeping the scope for recharging. The issue of excessive withdrawal of the ground water is always being discussed and people are more or less aware about it. While people are almost ignorant and indifferent at the same time about the issue of recharging ground water. And consequently the general people, even the government are continuously obstructing the recharging process.
Let me shed some lights on this very crucial issue.
Dhaka is a city of 13 million people. To accomplish the demand of this huge numbers of population, DWASA alone is extracting about 1500 million liters of water from the ground every day against its actual demand 2000 million liters. The rest of the demand is being fulfilled through the private initiatives which is also ground water based. But due to the lacking of recharging, a deficient situation is always prevailing in the water table. Our lacking of awareness about this issue is making the problem critical day by day.
As I have told at the beginning that the surface and ground water percolates down through the soil to join with the water table. Therefore, exposure of the soil to the water is a must in the recharging process. But the entire part of the soil surface of this city is blocked with the buildings, metal roads, tiles and plastics that prevent the water to be soaked by soil allowing it to be run off. As a result, despite having the significant amount of rain fall [206 cm/year], the water table is failing to be arisen up. We the city dwellers have taken the subversive attempt by covering each and every inches of our land with cemented blocks.
Again, water bodies have an important role on the ground water table. Water from the water bodies continuously seeps into the ground. It is unfortunate that all of the water bodies inside and outside of the Dhaka city are being filled up and covered with the buildings. Many real estate companies are desperately filling up all of the water bodies situated at the periphery of the city. The earth filling extravaganza of some housing companies/ project like Basundhara, Basumoti, Modhumoti, Jamuna etc is alarming us that all water bodies near the city will be finished within the few years which will be a cause of the ground water exhaustion.
Even the rivers are drying out. The volume of water in the Buriganga, Turag, Kaliganga, Shitalakshya is decreasing relentlessly. The encroachers are desperately grabbing these rivers. We often see the activity of reclaiming Buriganga from the encroacher. But, recently I have seen that the Shitalakshya, are being openly violated by some greedy people. Near the Kanchpure bridge almost a quarter of this river has been cordoned with the sand bags disrupting the water flow. Such encroachment of the adjacent rivers on the one hand, and the pollution on the other hand has created pressure on the ground water of the Dhaka from the two angles: [1] the low water in the rivers is causing the low recharge of the water table and [2] people are becoming depended more and more on the ground water giving up their previous practice of use of the river water. In the decades of 1980's we might have seen that many people on the both sides of the Buriganga are using its water for bathing and washing. Now this scene is rare.
Our lifestyle is also creating a significant pressure on the water of this city. We are extravagant in water use. Through the conservative use we can downsize the quantity of daily water need. For example, most of us have the habit of keeping our tap running during the shower, brushing the teeth, washing hands or using toilets, that allows a lot of water to be run off . For say, a person needs 25 gallons of water for a regular shower, but this shower is possible to complete with 4 gallons if the water is preserved in a bucket and pour it on the body using a mug. Like this, 19 gallons of water can be saved from a single shaving if it is done with the stored water. We have no habit of reusing or recycling the water. We have forgotten that water is the most valuable thing and it is limited. The conservative style of using the water can help to reduce the pressure on the ground water of this city.
During the rainy season we find the street of the Dhaka city is flooded with the rain water, while many people do not have safe water for their daily use. This rain water could be harvested to meet a big part of water demand of the city dwellers from early April to late September of a year. By creating the habit and practice of using rain water we can reduce the pressure on the ground water of the Dhaka city.
We should remember that we have no more time in our hand as we are already at the edge of the danger. Therefore, to avoid a catastrophic circumstance, we should start the conservative and judicious water use practice right now.
Author: Md. Firoj Alam
Published in The Bangladesh Observer, January 11, 2005
Also available at Environmental Articles Archive: Water Resources
Web version prepared by BCAS
January, 2005
