Dropping groundwater level
Groundwater table continues to fall in Dhaka city setting alarm bells ringing. A report on this was headlined on Sunday in this newspaper. According to the report the water pressure at the second layer or first confined aquifer is dropping alarmingly with the installation of 64 new deep tube-wells by the Dhaka Water Supply and Sewerage Authority (Wasa) in the past one year.
Rise or fall in groundwater depends on a number of factors including rainfall, geology and soil pattern. The increasing use of tube wells and the consequent spiral of deeper wells and receding underground water was only the first of a series of interconnected and mutually reinforcing vicious cycles that drove depletion of the aquifer. Rapid concretisation of the city is also a major factor in causing declining water levels. With rapid unrbanisation and the heavy construction work it entails there has been less percolation of rain water. As the water table falls, two things that is hitting Bangladeshis are that increasing percentage of the groundwater left is neither drinkable nor can be used for irrigation.
A significant part of the countrys groundwater resources are over-exploited. Groundwater extraction in some districts has reached levels when annual extraction exceeds water availability which, experts say, will have huge ramifications for agriculture, livelihoods and the whole economy. The failure to cope with the citys exponential population growth has only aggravated the situation.
Any solution to the countrys complex groundwater crisis will lie in tackling agricultural water use. Farmers need to be sensitised to the fact that it isnt excessive irrigation, but efficient irrigation that will give higher yields without draining the water table excessively. For industrial and domestic users, more technology intensive solutions like desalination projects, industrial and municipal water recycling can be explored.
However the major thrust should be on rainwater harvesting. The main advantage of rainwater capture is that it provides a more continuous and reliable access to water despite severe seasonal and meteorological fluctuations. It eases the stress on groundwater, rivers and basins and is therefore an ideal solution to water problems in areas with dwindling or inadequate water resources. Rainwater can be collected and stored within accessible distances, while traditional sources are often located away from the community. Rainwater is a clean source of water; the quality of rainwater is often better than ground water or water from rivers and basins.
