Rainwater harvesting as an alternative option for sustainable water management of Dhaka city

摘要

Despite the advancement of technology in the recent past, the global scenario still remains grim in water supply as not all the inhabitants of the world have access to safe drinking water. Dhaka city is now facing tremendous challenges to fulfil the water demand of its inhabitants. Groundwater table depletion is increasing at an alarming rate. This study mainly focuses on the potential of a rainwater harvesting system in Kazipara area of Dhaka city. The study area has typical characteristics of an unplanned, congested development with a small plot size of Dhaka city. That is why this area has been chosen. Residents of this area face both water crises in dry summer and water logging in monsoon. It has been calculated that the potential of rooftop rainwater harvesting is 4,02,096.34 cubic meter water/year which can meet about a 66% demand of water for toilet flushing and cleaning purposes used by the residents of Kazipara all year round. If a rainwater harvesting system is used every buildings of the study area then 2,872.12 cum/hr surface runoff would be reduced during a rainfall event of 15 mm/hr, which means 61.71% of surface runoff would be reduced from the current surface runoff. As a consequence, water logging problem can be decreased in Dhaka city.