SUSTAINABILITY APPRAISAL OF TAIPEI MUNICIPAL WATER SUPPLY SYSTEM

system dynamics The purpose of this study is to develop a simulation model to evaluate sustainability of water supply systems for Taipei municipal and neighbor areas. The definition of sustainability is addressed first, which indicates that sustainable development requires keeping cumulative impacts not exceeding environmental carrying capacity. The carrying capacity of a water supply system is the quantity of potential water supply which depends on water resources facilities and hydrological conditions. Thus, sustainability of a water supply system needs total water demands less than its potential water supply capacity. Besides, difference between water demand and water supply should be in an acceptable range (such as 10 % of water supply). A water supply system dynamics model was developed in Vensim 4.0 for the Danshuei river watershed and applied to evaluate sustainability of Taipei, Banshin, and Shihmen water supply districts. Before appraisal study, historical streamflows were used to verify the model. Validation indicates that the model can provide reasonable simulations. Then, the model was applied to assess sustainability. The results indicate if water loss of distribution system can be improved and Taipei district supply of 5.3×105 m3 d-1 to Banshin district, three water supply districts are sustainable by year 2025. However, it does not imply no drought event, because carrying capacity of water supply is determined based on the criterion of shortage index = 1