Rainwater harvesting potentials for a water-scarce city in Bangladesh

The potential for a rainwater harvesting (RWH) system to supplement the water supply in Chittagong city, Bangladesh, was assessed. Two years were selected for the analysis (2006 and 2020); the projected rainfall for 2020 was evaluated using the Statistical Downscaling Model. Data on projected runoff, land use changes, population growth and catchment areas were also accumulated. The whole city was divided into 22 sub-basins and 176 354 building rooftops were studied for RWH opportunities. Using the weighted linear combination method in a geographic information system environment, potential rooftops and zones were identified for 2006 and 2020. The results showed that the areas with a high RWH potentiality index could supplement water demand by up to 13.03% and 29.68% in 2006 and 2020, respectively. With proper data, this novel approach for a decision support system can be applied to investigate RWH potential in any urban area.