以SPOT影像及數值地形模型推估集水區泥砂產量

Prediction of Sediment Yield Using SPOT Imagery and Digital Terrain Model

江陽聖(Yang-Sheng Chiang) ； 陳錕山(Kun-Shan Chen) ； 梁隆鑫(Long-Shin Liang) ； 王志添(Chih-Tieh Wang)

《航測及遙測學刊》 12卷4期 (2007/12) Pp. 447-456

https://doi.org/10.6574/JPRS.2007.12(4).13

摘要

本研究應用光學SPOT衛星影像進行2001-2006年石門水庫、頭前溪、大甲溪、高屏溪上源集水區裸露崩塌地判釋及泥砂沖蝕量推估，研究首先藉由實驗樣區植生分析，並應用數值地形模型探討崩塌發生的區位特徵，制定出崩塌判釋標準流程，分析並探討歷年崩塌變遷狀況，並藉由現地調查及航照判釋資料進行判釋成果的比對驗證，研究顯示2006年石門水庫、頭前溪、大甲溪、高屏溪上源集水區裸露崩塌地面積分別爲634 ha、236 ha、1189 ha、4308 ha。在集水區產砂推估上，首先制定泥砂沖刷演算流程，區分點源及非點源式的產砂來源，其中非點源式的表土沖刷以通用土壤流失公式進行推估，點源式的產砂來源則以判釋崩塌區及崩塌深度進行分析，再藉由泥砂遞移概念演算進入庫區或集水區出流點的砂石總量，並分析歷年變化狀況。經由分析演算，歷年表土沖刷變化與年降雨量呈現相關，而在空間分布上，高表土流失區域與裸露崩塌區位相符合，2006年以上各集水產砂量分別爲1,070,097m3、323,540m3、1,836,431m3、4,824,430m3。經與石門水庫歷年實測清淤量及淤砂量的比對分析，此泥砂沖刷演算值與產砂變遷趨勢一致。

關鍵字

崩塌地 ； 產砂量 ； 數值地形模型 ； 通用土壤流失公式 ； SPOT衛星

並列摘要

Heavy rainfall often triggers widespread soil erosion and landslide hazard in mountainous terrain, resulting in sediment deposition and loss of reservoir capacity. This research aims to identify major sediment sources and predict watershed yield by using satellite images and GIS techniques. Optical satellite images, specifically those of SPOT series, were used to identify landslide areas from 2001 to 2006. To distinguish landslides from high vegetated areas, field studies were conducted for investigation of normalized difference vegetation index (NDVI) covering several major land covers to determine the threshold value for bare land. Slope features, based on spatial analysis of Digital Terrain Model, were also introduced to differentiate landslide from other low vegetated area. Study showed that landslide covered about 634 hectares at Shihmen Reservoir, 236 hectares at Touchien catchment, 1,189 hectares at Dajia catchment, and 4,308 hectares at Kaoping catchment in post-typhoon season images of 2006.
To estimate soil erosion and the mechanism of sediment transport, the Universal Soil Loss Equation (USLE) and soil delivery ratio were used to estimate non-point sources of soil erosion, and those of point sources were determined by the identified landslide areas, which were then multiplied by the predicted depth of weathered layer to obtain the total volume. Study indicated that the sediment yield of Shihmen Reservoir, Touchien Creek, Dajia creek, and Kaoping Creek were estimated as 1,070,097 m3, 323,540 m3, 1,836,431 m3, 4,824,430 m3, respectively. Finally, under the assistance of Northern Region Water Resources Office, our predicted results were validated by the measured sediment yield of Shihmen Reservoir.

並列關鍵字

Landslide ； Sediment Yield ； Digital Terrain Model ； SPOT Image ； Universal Soil Loss Equation