Project Name: Research Study on Storage and Recharge Potential of Rainwater in Dhaka City to Promote Ideal Practice of Rainwater Harvesting System in Urban Areas
Name of Client: WaterAid Bangladesh
Period: October, 2012 to September, 2015 (36 Months)
Description of Project:
Rainwater collected from clean rooftops is generally free of mineral pollutants like fluoride and calcium salts which are generally found in ground water. But it is likely to be contaminated with other types of pollutants: air pollutants and surface contamination (e.g., silt, dust). The cleanliness of the roof in a rainwater harvesting system most directly affects the quality of the captured water. Maintaining the quality of water is very important for long-term storage. Well designed rainwater harvesting systems with clean catchments and storage tanks supported by good hygiene at the point of use can offer drinking-water with very low health risk, whereas a poorly designed and managed system can pose high health risks. The quality of rainwater may deteriorate during harvesting, storage and household use. Poor hygiene during storing and collecting water from tanks or at the point of use can also cause health concerns. However, risks from these hazards can be minimized by good design and maintenance using technologies.
Therefore, the quality of stored rainwater for direct use will be monitored for different seasons. It will also be monitored how the quality of stored rainwater changes with time. The identification of contamination sources is also important to avoid deterioration of rainwater quality.
The water supply sector in Bangladesh is largely dependent on ground water source. In Dhaka city, 87% of the city supply is covered by ground water. This over extraction of ground water from aquifers, supplemented by the paved area, which reduces the chance of infiltration of rainwater, has worsened the scenario. As a result, lots of tube wells are getting abandoned every year for the depletion of ground water table. Therefore, interventions must be undertaken to arrest the rate of ground water declination in areas like Dhaka. The recharging of aquifers by rainwater harvesting through recharge wells could be a good solution where the rainwater will be channeled from the catchment area to the recharge wells and finally to the aquifer after filtration. To evaluate the success of recharge system, hydro-geological analysis of the whole system will be needed to develop a guideline and overcome the constraints that could hinder the recharge system. Successful implementation and the results will help to develop the system which will definitely benefit the ongoing water crisis of Dhaka city and other water scarce areas.