Evaluation of Required Capacity of Rainwater Harvesting System to Mitigate Typhoon-Induced Water Shortage in Southern Taiwan

The water shortage of today’s world is one of the most challenging problems and the world is looking for the best solution to reduce the crisis. Some human made causes and also natural causes such as less rainfall, economic development, rapid urbanization, natural hazards (typhoon, earthquake), structural failures and repairs, etc., are liable for the shortage of the existing water supply system. In Taiwan, especially during summer time, a lot of typhoons occurred and during that typhoon period, the turbidity of raw water increases beyond the treatment capacity of a treatment plant and the plant cannot supply required amount of water. To cope with the system, a couple of days are needed and during that period, there would be insufficient supply towards demand for a few days which causes shortage. The purpose of this study is to cope with this emergency shortage problem. A dual-mode Rainwater Harvesting System (RWHS) was used in this study as a supplemental to the existing water supply system to support some selected secondary/non-potable components such as toilet flushing and urinal flushing. This system was able to supply water both for ordinary uses and for emergency uses. An optimal design algorithm for this research work was developed. YAS (yield after spillage) and YBS (yield before spillage) both of the behavioral models were considered to evaluate the best suited for this system. The efficacy and reliability of the system were also evaluated from this study