圖書典藏及影音數位平台

為掌握氣候變遷對水環境影響，水利署自98年啟動氣候變遷相關科研工作，並引用聯合國氣候變遷專門委員會(IPCC)之第四次評估報告情境模式進行降雨量之推估，惟目前IPCC已於103年提出第五次評估報告(AR5)，因AR4與AR5使用情境假設不同，為一步了解，兩者於臺灣氣候推估之差異性，及對原AR4所模擬的降雨量之影響，爰研擬本計畫對AR4與AR5降雨量之時空變異性分析及評估可能之衝擊。

This project aims to discuss the impact to flood and drought caused by the rainfall variation between IPCC AR4 and IPCC AR5. The impact on water resources and flood caused by the spatial and temporal variation of rainfall is also evaluated in this project for further adjustment of adaption strategy. In the past, the adaption strategies to the high risk area were based on the IPCC AR4 data. However, the IPCC AR5 data was announced recently and used different scenario from IPCC AR4. Thus, the rainfall difference between IPCC AR4 and IPCC AR5 and its influence to the adaption strategy are the goal of this project. This project is scheduled from 2016 to 2017. It will focus on the rainfall variation between AR4 and AR5 and its impact on water resources and flood prevention in the first year. Then, the adjustment of adaption strategy will be discussed based on the sensitivity analysis in significant rainfall varied area in the second year project. The contributions of this year are as follow. 1. The scenario selection of AR4 and AR5 Most researches indicate that the comparison of CO2 concentration between AR4 and AR5 is good solution for the scenario selection problem. Based on the A1B, A2 and B1 scenario selections in AR4 projects, the corresponding scenario selections are RCP4.5 and PCP8.5 in AR5. 2. The selection of suitable AR5 GCM in Taiwan There are four main points of view, hydrological climate, meteorological, multiple model ensemble and weighted model ensemble, for the GCM selection in most researches. Also, the selection in AR4 should be considered for the fair comparison. The hydrological climate point of view and meteorological point of view are adopted in the water resources aspect of AR5. The multiple model ensemble point of view is adopted in the flood aspect of AR5. 3. Analysis of rainfall variations between AR4 and AR5 under the requirement of water resource aspect. The study area is in the upstream of primary watershed in four (Northern, Central, Southern, Eastern) main parts of Taiwan. Based on the analysis of worst GCM case, the rainfall will decrease during dry season in AR5. The rainfall of Northern, Central and Southern parts of Taiwan will increase in wet season in AR5. However, the decreasing amount in dry season is much less than the increasing amount in wet season. 4. Analysis of rainfall variations between AR4 and AR5 under the requirement of flood aspect. It will focus on several rain gauges in five watersheds (Tamsui River, Dajia River, Zhuoshui River, Zengwen River, Gaoping River). Based on the analysis of worst GCM case, most watersheds indicate the increasing trend in July especially in the Tamsui River watershed. By setting the buffer zone of 10% to AR4 rainfall, the AR5 rainfall has significant increasing in Tamsui River watershed. Furthermore, the frequency analysis of extreme rainfall (1-day and 2-day return periods) will also introduce in this study. The extreme rainfall of AR5 in most rain gauges within these five watersheds are higher than the extreme rainfall of AR4. However, we should do further statistical analysis to clarify whether the changes are significant in the project of next year.