HEC-RAS 2D於天然壩潰決模擬評估

Apply HEC-RAS 2D on Natural Dam Breach Assessment

林家興(Chia-Hsing Lin) ； 吳振佑(Chen-Yu Wu) ； 蔡元融(Yuan-Jung Tsai) ； 陳振宇(Chen-Yu Chen)

《中華防災學刊》 11卷2期 (2019/09) Pp. 137-150

摘要

本文應用HEC-RAS 2D模式以及崩塌前DEM與崩塌後UAV拍攝資料，進行天然壩潰決模型建置及洪水演算。在2017年6月3日，於南投縣小半天瀑布下游發生邊坡崩塌，造成河道堵塞，形成堰塞湖。使用HEC-RAS 2D進行潰決模擬時，避免在壩體穩定性未明情況，衍生之現勘人員傷亡的風險。目前潰壩模式能提供潰壞機制及潰壩參數，可進行參數調整，以此評估潰決影響方案探討。演算結果顯示堰塞湖潰決並未對下游造成明顯的水位變化，但在靠近堰塞湖附近則受到較嚴重的影響，而其洪水波沿著下游逐漸遞減。應用HEC-RAS 2D緊急評估其對下游保全住戶之影響，對政府部門於災情應對與避難決策上有直接助益。

關鍵字

洪水演算 ； 天然壩 ； 潰壞模式 ； 潰決參數

並列摘要

This paper applied the HEC-RAS 2D to analyze the natural dam break and resultant floods based on field investigated geometry data from UAV and pre-event DEM data. On 03 June 2017 a rainfall-induced landslide occurred in the Xiou-Ban-Tien, Nantou County and formed a landslide dam lake. The natural dam breach was modeled and analyzed using HEC-RAS 2D to lower the damage of people in field investigation under potential dam breach condition. The HEC-RAS 2D supply the modules of failure mechanism and dam breach parameter for unsteady flow routing with dam breach analysis. The simulation scenario considering different dam breach parameters and failure mechanism. The result indicate that the landslide dam lake break does not increase the downstream maximum water level significantly. Dam break has a severe impact on the downstream reach near to it and the water level of flooding wave gradually decrease at different downstream locations. HEC-RAS 2D model can provide government officials to mitigation support and response to hazard assessments.

並列關鍵字

Flood Routing ； Natural Dam ； Dam Failure Mode ； Dam Breach Parameter