Establishing a Methodology to Evaluate the Capabilityof Water Supply and Flood Mitigation of the Shihmen Reservoir under Climate Change

• Main Authors: Yi-Hsin Ho, 何宜昕
• Other Authors: Ching-Pin Tung
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/05392946167679051701

碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 98 === The frequency of extreme hydrological events in Taiwan have been obviously increasing recently and greatly impacted the function and operation of the reservoirs. The purpose of this study is to investigate the effects of climate change on water supply and flood mitigation capacity in Shihmen Reservoir. The effects including water shortages due to low flows and the high turbidity inflows in storm period and the risk of overflow under the current flood mitigation regulations are assessed in this study. First, the change point of climate is derived through analyzing the historic temperatures and rainfall data. The statistical properties of weather data in a period before the change point are served as baseline, and then the baseline statistical properties are adjusted to setup future climate scenarios according to the future temperature and rainfall changes projected by the outputs of General Circulation Models. Possible future daily and hourly weather data based on different climate scenarios’ statistical properties are generated by a continuous weather generator. The hydrological model developed by Tung and Lien (2009) is further used to simulate daily and hourly discharges. Historical relation between peak discharge and peak turbidity measured in the reservoir is constructed to project the possible turbidity in the future flood events. According to the Shihmen operational regulations for both ordinary days and event periods, the impacts of climate changes on water supply ability in drought period, in high-turbid period, and flood mitigation capability, are assessed. The results indicate that the water supply ability of Shihmen Reservoir may have decline trend because of less flow in dry periods. Furthermore, the climate change may exacerbate the shortage of water resource and impact the economics of Tao-Yuan region, especially agriculture. Withdrawing water from new water intakes during the high turbid period will significantly improve water supply ability. In addition, the results show that Shihmen Reservoir may increase the probability of overflow due to climate change.