本研究使用單向耦合的大氣水文模式系統，進行颱風及梅雨的定 量降雨系集模擬研究，以瞭解員山子分洪與預測降雨的關係，並探討 在集水區河川水位模擬中預測降雨之不確定性，其目的在於提前得知 大雨來臨時，員山子是否會達到分洪條件，並提供管理者決策的依據， 且相關單位與人員可以進而事先採取因應措施，有效防範及減低災害 所帶來的損失。本研究欲探討之降雨事件為2012 年的蘇拉颱風，以 及2013 年梅雨事件，該颱風於8 月2 日登入台灣，分洪量為員山子 歷年來的最大值，故本研究選擇此降雨事件來進行水文模擬的討論。 本文利用台灣颱風洪水研究中心模擬78 小時之降雨預報，以不 同的積雲、微物理及邊界層等物理參數法建立20 組系集成員，並依 照不同時段之降雨預報，來探討員山子分洪情形及系集預報之不確定 性的範圍，從蘇拉颱風降雨事件的結果發現，隨著接近降雨事件發生 時間，員山子分洪的機率呈現上升的趨勢，且在洪峰前17 小時就能 準確預測員山子將會分洪。本研究將不分洪的成員忽略，探討所有時 段之預測降雨都有分洪的成員。將78 小時平均累積降雨結果顯示， 累積降雨在17 小時的預測最佳。就個別成員而言，洪峰到達時間及 洪峰水位為23 小時及17 小時的預測較佳。本研究可以將模擬並推估 分洪警戒及洪峰的可信任範圍的資訊，提供給想要以颱洪中心的定量 降雨作為預報資訊的決策人做為參考，並且可以提供員山子分洪管理 中心值勤人員提早預警，並爭取操作應變及通報作業時間。;In this study, single coupling atmospheric hydrological model system is employed to simulate the integrating quantitative precipitation of typhoon and plum rain. According to the simulation, it is helpful to realize the relation between the diversion in Yuan Shan Zi and the forecast of rain. Investigate the uncertainty of integrating quantitative precipitation in the water level simulation of river basin to reach the goal which is learn whether the water level will reach the requirement of diversion in Yuan Shan Zi or not before the heavy rain is coming. This study is expected to provide to manager as a foundation of the decision, and the related units can get response measures previously to decrease the damage from the disaster. In this study, the issues which are chosen are Su-La typhoon in 2012 and the plum rain in 2013. Su-La typhoon is chosen because its diversion in Yuan Shan Zi is the largest in the recode. The forecast of rain for 78 hours which is developed by Taiwan Typhoon and Flood Research Institute is employed in this study. It uses different physical parameters to develop 20 sets of forecast. To investigate the situation of diversion in Yuan Shan Zi and the range of the uncertainty in the forecast with different time step, the result of Su-La typhoon shows that the probability of diversion in Yuan Shan Zi tend to increase with the time getting close to the raining issue occur. The diversion in Yuan Shan Zi can be forecasted accurately for 17 hours prior than the peak. Every result which is not diversion in Yuan Shan Zi is ignored. The result of the average cumulative rainfall for 78 hours display that the result of the cumulative rainfall for 17 hours is best forecast. For specific set, the best forecast of the time peak and the water level are shown at 23 and 17 hours. The study can offer the simulation and estimate the information of diversion and peak within the credible range. It can provide the manager who wants to use the result of the integrating quantitative precipitation as IV forecast, and the staff in the Yuan Shan Zi diversion management center as a prior alert to save the time of operation and circular.
