Applying GIS-based rainwater harvesting design system in the water-energy conservation scheme for large cities

Urban water supply systems consume energy for distribution. Saving potable water therefore implies saving energy. Using hillside communities of Taipei Metropolitan as a case study, this study proposed a GIS-based rainwater harvesting design system incorporating spatial technologies, hydraulic simulation and economic feasibility to explore how rainwater harvesting systems (RWHSs) can be a cost-effectively tool in urban water-energy conservation planning. The results clearly indicate that the economic feasibility of RWHSs was significantly enhanced when water and energy savings are both considered. Moreover, well-designed RWHSs can alleviate the water-energy shortage caused by rapid urbanization.