GIS-based decision supporting system in hydraulic simulation and economic analysis for rainwater harvesting design

Rainwater harvesting systems (RWHSs) are increasingly important to enhance the availability of water resources around the world. However, the RWHS´s limitations, i.e. the influences due to the spatial and temporal variation of rainfall, have not been properly addressed in developing a scientific system for RWHS design. This study establishes a GIS- based decision supporting system (DSS) incorporating hydraulic simulation and economic analysis (Benefit - Cost-Ratio, B/C), and uses the rooftop RWHSs in Taipei City as a case study. Two RWHS designs were tested in DSS to visualize the spatial distribution of the reliability and B/C ratio, and to seek the optimum design. Sensitivity analysis also verifies that the DSS renders higher information value than the traditional generalized method. Hence, as a feasible tool, this DSS has potential in promoting the participation and application of RWHS.