臺灣南部流域長期降雨與逕流量變異之探討

An Analysis on the Variation of Long-term Precipitation and Streamflow for Watersheds in Southern Taiwan

李忠勳(Chung-Hsun Lee) ； 葉信富(Hsin-Fu Yeh)

《臺灣鑛業》 72卷1期 (2020/03) Pp. 10-24

摘要

近年來全球環境發生變遷，在臺灣水土資源珍貴難得的情況下，評估氣候變遷與人為活動對水文環境造成的影響成為重要的水資源課題。本研究選取臺灣南部區域的八掌溪、曾文溪、鹽水溪、二仁溪、荖濃溪、隘寮溪、東港溪及林邊溪等8個流域1950年後可得之水文資料作為研究對象，以Mann-Kendall趨勢檢定法檢測降雨與流量資料的顯著趨勢，並使用Mann-Whitney-Pettit檢定法區分流域之基準期與改變期轉折點，而後透過雙累積曲線分析降雨與逕流之一致性與變異，可評估氣候因子與非氣候因子造成流量之變化百分比。結果顯示8個流域中，雨量以曾文溪與二仁溪流域具顯著增加趨勢；流量則以八掌溪、曾文溪、荖濃溪與隘寮溪具顯著轉折點，其中曾文溪與隘寮溪則發生第二轉折點。該4個流域於第一轉折點發生前後，觀測逕流量之改變量依序為48.27、-13.37、65.96及-36.96%；曾文溪與隘寮溪之第二轉折點相較基準期之逕流改變量為113.92、-1.05%（負值表示減少）。以雙累積曲線法計算氣候變遷對八掌溪、曾文溪、荖濃溪及隘寮溪流域之影響，在第一轉折點氣候變遷造成的流量變化比例依序為總改變量之44.91、-125.44、99.41及32.02%；曾文溪與隘寮溪之第二轉折點則分別占總改變量70.06、-459.81%。此結果可供未來臺灣南部區域各流域在治理與政策規劃上作為參考。

關鍵字

集水區 ； Mann-Kendall & Mann-Whitney-Pettit檢定法 ； 雙累積曲線 ； 氣候變遷

並列摘要

Recently, climate change and other environmental changes brought by human activities have impacted the hydrological environment worldwide. It has become important to assess the water resource variation in the environment. In this study, the Bazhang River, Zengwen River, Yanshui River, Erren River, Laonong River, Ailiao River, Donggang River, and Linbain River Basins in southern Taiwan were selected as study area. As a part of this research, several tests and analysis methods were used. The Mann-Kendall trend test was used to detect the significant trends of precipitation and streamflow data, the Mann-Whitney-Pettit test was used to identify the break points of hydrological data, the double cumulative curve was used to analyze the consistency and variation of precipitation and streamflow, and finally the percentage changes in streamflow caused by climatic change and non-climate factors could be assessed. The results revealed that significant break points could be detected in the Bazhang River, Zengwen River, Laonong River, and Ailiao River Basins, among which two break points were present in the Zengwen River Basin and Ailiao River Basin, respectively. In the first variation period (post-breakpoint), the changes of observed streamflow were 48.27%, -13.37%, 65.96%, and -36.96%, respectively. In the second variation period, the changes in the Zengwen River Basin and Ailiao River Basin compared with the baseline period were 113.92% and -1.05% (negative value indicates a decrease), respectively. The impacts of climate change in the Bazhang River, Zengwen River, Laonong River, and Ailiao River Basins were calculated using a double mass curve, which indicated that the streamflow changes caused by climate change at the first break point were 44.91%, -125.44%, 99.41%, and 32.02% of the total change, respectively. Additionally, climate change accounted for 70.06% and -459.81% of the total change in the second variation periods of the Zengwen River Basin and Ailiao River Basin, respectively. These results can be used as a reference for governance and policy management in the basins of southern Taiwan.

並列關鍵字

Watersheds ； Mann-Kendall trend & Mann-Whitney-Pettit test ； Double mass curve ； Climate change