高屏溪流域上重要河川橋之橋基及其保護工的災害分析，國內橋樑常遭遇受損原因可大致分為：砂石開採、一般沖刷、局部沖刷、束縮沖刷或保護工分離、固床工跌水沖刷、大尺度二次流侵蝕、通洪斷面或寬度不足、泥石流或漂流木之撞擊與磨損、位於河川彎道處或滙流挑水效應、軟岩之風化與沖蝕、橋樑基樁貫入深度恐有相對不足或裸露等因素。本文針對河川流量通過橋樑時，在橋樑斷面上游所造成之水面線壅高情形，應用HEC-RAS作一維之數值模擬分析，提供橋樑設計之相關工程師作為參考。並以HEC-RAS 來模擬水位變化情形並評估對橋樑、堤防安全等影響。

The disaster analysis of the bridge foundations of important rivers and bridges in the Gaoping River Basin and their protection works shows that the causes of damage to domestic bridges can be roughly divided into: sand and gravel mining, general scouring, local scouring, shrinkage scouring or separation of protection workers, and solidification. Bed work falling water erosion, large-scale secondary flow erosion, insufficient flood section or width, impact and abrasion of mud-rock flow or driftwood, water-carrying effect at river bends or confluence, weathering and erosion of soft rock, bridge foundation piles The depth of penetration may be relatively insufficient or exposed. This article applies HEC-RAS as a one-dimensional numerical simulation analysis for the high water surface line caused by the upstream of the bridge section when the river flows through the bridge, and provides the relevant engineers of the bridge design as a reference. And use HEC-RAS to simulate water level changes and evaluate the impact on the safety of bridges and dikes.