坡地崩塌對河道流量–輸砂量率定曲線及集水區產砂量影響之研究

本研究使用水利署長期流量與輸砂量觀測資料，輔以崩塌面積變遷趨勢及河道斷面資料，以瞭解高屏溪河道輸砂特性改變之情形，研究結果顯示，高屏溪流域相同流量條件下河道之輸砂量於2009年有明顯增加，並於2012年開始河道輸砂特性會趨於穩定，但仍高於2009年以前之輸砂量，造成差異主要之原因為集水區受莫拉克颱風影響，導致地文環境之變動，使輸砂特性出現明顯改變。因此，本研究配合莫拉克颱風事件發生時間，分期建立河道流量-輸砂量率定曲線，進一步檢核高屏溪流域現有5處水文站流量–輸砂量率定曲線之問題；同時，應用地文性土壤沖淤模式獲得涵蓋高低流量下之輸砂量資料，建立可信之流量–輸砂量關係，以修正實測之流量–輸砂量率定曲線，研究結果顯示修正後之率定曲線迴歸係數更加，且實測之率定曲線有低估的情形。另分析崩塌面積與降雨對於沖蝕量與產砂量之影響，結果證實隨崩塌裸露面積的增加，沖蝕量與產砂量亦有所增加，且變化情形大致與歷年新增崩塌面積變化相符。同時，沖蝕量及產砂量會受到累積雨量及降雨強度之影響，但其變化受到累積雨量影響為主，而降雨強度為輔助因素。

關鍵字

崩塌；地文性土壤沖淤模式；流量–輸砂量率定曲線；土壤沖蝕；產砂量

並列摘要

In order to understand the influence of landslide on sediment transport characteristics at Kaoping Watershed, long-tern records of daily discharge, suspended sediment concentration, landslide change trend and cross-section survey data were used in this study. The results show obvious sediment transport changes between 1995 and 2018, and were associated to Typhoon Morakot. Sediment rating curves were separated into three periods according Typhoon Morakot. In the analysis of sediment yield, the study collected historical discharge and sediment transport data from Lilin bridge station, San-Di-Men station, Shan-Lin bridge station(2), Da-Jin bridge station(1) and Liou-Guei station(1) in the upstream of the Kaoping River.The Physiographic Soil Erosion-Deposition (PSED) model was used to simulate high flow period and suspended sediment transport caused by different typhoon and storm events in order to check the sediment rating curve of the five hydrological stations. The result shows that the curve tends to underestimate sediment transport. The Influencing of factors on soil erosion and sediment yield were bare land at landslide, accumulated precipitation and rainfall intensity.The analysis show that when the bare land at landslide increases, sediment yield and soil erosion will also increase.Subsequently, soil erosion and sediment yield will be affected by accumulated precipitation and rainfall intensity, but their changes are mainly affected by accumulated rainfall, and rainfall intensity is an auxiliary factor.