台灣位處於板塊交界帶,地震頻繁,地質構造脆弱,每逢颱風豪雨季節,山坡地易發生土石崩落之現象,堰塞湖形成原因是河道兩側邊坡經地震、降水等自然力作用,導致土石體崩塌阻塞河道,使溪水無法向下游流動,造成溪水斷流,在崩塌地上游蓄積水體而成湖泊之天然壩體。在921地震後,許多山坡地地質結構鬆裂,容易發生山崩、土石流、地滑等,前後促使形成大小不一之堰塞湖約有十餘座,有鑑於此,評估堰塞湖帶來之災害規模及嚴重性是刻不容緩之事。 本研究利用O’Brien and Julian於1998年設計之FLO-2D數值模擬軟體,配合龍泉堰塞湖堆積之土砂量與後方迴水之蓄水量,再搭配數值地形資料來模擬堰塞湖潰壩後發生土石流之影響範圍,包括堆積深度、流動速度,並參考物理模型試驗結果,藉由無橫向構造物、單座橫向構造物與二座橫向構造物之設置等三種境況之模擬評估,可初步了解土石流發生之影響範圍,作為未來相關單位整治之依據。
Taiwan located on the junction of tectonic plates, the earthquake are frequent and the geologic structure are broken. Every time the typhoon brings torrential rain cause, the hillslope was easy to avalanche phenomenon. Landslide dams have prove to both by earthquake and precipitation natural phenomena that cant hinder the river by the soil and stone of slop collapse. Since the 921 earthquake broken up geologic structure that easy happened avalanche, debris flow, landslide and landslide dams to accelerate no-uniform size approximately has ten. Had up to this, assumed the landslide dams brings the disaster scale and the gravity is brooks no delay the matter. The study used the FLO-2D Model designed by O’Brien and Julian in 1998, which coordinated sediment volume, amount of water stored and digital terrain model to analyze the situation of dam breaking influence scope debris flows, including sediment depth and flow rate by put up transverse non-dike, one-dike and tow-dike of treatment that to be helpful to expect the damage caused by debris flows to provide offices dredged in the future.