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A Study on the Priorities of Management for Watershed Sediment Hazards at the Kuanyinkeng Creek
|關鍵字:||Sediment Delivery Ratio;泥砂遞移率;Watershed Sediment Yield;Not-Exported Sediment Load;集水區泥砂產量;未輸出之泥砂量||出版社:||水土保持學系||摘要:||
本研究以台中縣和平鄉境內，大安溪上游雙崎部落之觀音坑溪集水區為研究範圍。利用SPOT衛星影像及數值高程模型為材料，地理資訊系統（GIS）及集水區資訊系統（WinGrid）為工具，探討集水區內泥砂產量及未輸出之泥砂量。集水區泥砂來源主要為坡面沖蝕及崩塌地，本研究以通用土壤流失公式（USLE）計算坡面沖蝕，並由七二水災前後期之SPOT衛星影像萃取崩塌地，輔以Khazai and Sitarz概算崩塌量，配合泥砂遞移率（SDR）觀念，推估集水區泥砂產量。
由土石流發生潛勢及保護對象等條件，可得知觀音坑溪集水區土砂災害潛勢高危險等級。進一步由各子集水區之未輸出泥砂量、保護對象及現存之崩塌量，評估各子集水區土砂災害區位治理優先順序。由分析得知；子集水區編號1及3之未輸出泥砂量分別達31,680 m3及78,239 m3，易因降雨誘發災害，且區內存在建築物及道路等保護對象，需優先治理。
Upstream of Daan stream, the kuanyinkeng watershed, ShuangChi tribe, Heping Township, Taichung County, was taken as the study site. SPOT satellite images and the Digital elevation model (DEM) data were used as the input data, and the Geological Information System (GIS) as well as the watershed information system, WinGrid, were the tools to incorporate SPOT satellite images and DEM data, so as to investigate the sediment yield and not-exported sediment load within the watershed. The main sediment sources of the watershed are from soil erosion as well as landslides, so this study uses the Universal Soil Loss Equation (USLE) to estimate the eroded soil volume, utilizing the SPOT satellite images before and after the July 2th disaster to extract and delineate the landslide area, employing the Khazai and Sitarz method to calculate the slided soil volume, incorporating the concept of Sediment delivery ratio (SDR) to estimate the sediment yield of the watershed.
In view of the debris flow potential and protection targets, it can be known that the sediment disaster potential of kuanyinkeng watershed is rated as the high-risk level. Furthermore, each sub-watershed's exported sediment load and protection targets and existing slided material were used to assess the priority for management over sediment disaster areas of each sub-watershed. The results show that the sub-watershed No.1 & No.3 have the not-exported sediment loads of 31,680 m3 and 78,239 m3 respectively, which might easily cause disaster, in which the protection targets such as building and roads should have a top priority for management.
Watershed sediment control is an important topic, so this study considers the watershed not-exported sediment load and quantifies the sediment distribution within watershed, which is used to arrange the sequence for management of watershed sediment disasters and for governments or relevant authorities to perform relevant management and restoration works. It is believed that by doing so, the residents' life and property in mid and lower reaches of kuanyinkeng Stream will be safer and more secured.
|Appears in Collections:||水土保持學系|
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