氣候變遷下高屏溪堤防風險度之研究

The Risk Analysis of Dike Safety of Koaping River due to Climate Change

林永峻(Yong-Jun Lin) ； 張倉榮(Tsang-Jung Chang) ； 王嘉和(Chia-Ho Wang) ； 賴進松(Jihn-Sung Lai) ； 譚義績(Yih-Chi Tan)

《農業工程學報》 59卷4期 (2013/12) Pp. 81-99

https://doi.org/10.29974/JTAE.201312_59(4).0008

摘要

全球氣候變遷對於各國皆造成很大的衝擊，針對洪水災害的衝擊最直接的因子就是水文現象的改變，其中包含極端降雨導致逕流與淹水面積增加、海平面上升與河口水位頂托使河川沿岸溢堤風險增加等。此外，坡地崩塌加上強降雨造成河川含砂量增加，恐造成河道之沖淤加劇。本研究首先進行未來情境下水文因子情境之設定，包含氣候變遷情境下雨量、上游流量及河口水位等，再利用一維水理模式HEC-RAS進行河道水理計算得到未來情境下的水位。在本研究中風險度等於危險度與脆弱度之乘積，影響堤防危險度之因子包括：河川水位高程、漂流木影響程度、河床刷深及淤積程度、單位河川功率、歷史溢破堤頻率；而脆弱度之因子包括：堤防護岸附屬水利設施、堤防護岸年齡、堤岸類型、堤防護岸位置、堤岸狀況。各因子之權重採用問卷與AHP（Analytic Hierarchy Process）層級分析法訂出，最後進行堤防危險度、脆弱度及風險度之分析，所得結果可為未來氣候變遷下高屏溪提防安全之參考，相關方法亦可應用至其它河川。

關鍵字

氣候變遷 ； 堤防 ； 危險度 ； 脆弱度 ； 風險度

並列摘要

Global climate change has huge impact on countries all over the world. The direct impact to flooding is the change of hydrological conditions due to climate change. The extreme rainfall may lead to the increase of runoff and area of flooding. The sea level rises and thus affects the drainage of river flow in the estuary which also increases the risk of overflow of embankments. In addition, landslide occurring in the slope land triggered by heavy rainfall may yield more sediment flushing into the river and could lead to dramatic erosion and deposition in the river.Frist, the hydrological conditions of future scenario of rainfall, discharge of upstream boundary, and water surface level of downstream boundary are set. The one-dimensional hydraulic model-HEC-RAS are performed to get water surface level under future scenario. In the present study, the ”risk” is defined by ”hazard” multiplying by ”vulnerability”. The factors counted in ”hazard” include: water surface elevation, influence of drift wood, river erosion or sediment depth, unit stream power, frequency of historical dike failure; and the factors counted in ”vulnerability” include: hydraulic structure of banks, and age, type, location, and condition of dike. The weighting of those factors are gotten by questionnaires and AHP (Analytic Hierarchy Process). The risk of the dike of Kaoping River due to climate change is then obtained by multiplying hazard and vulnerability. The proposed methodology can also be applied 10 other rivers.

並列關鍵字

Climate change ； Dike ； Hazard ； Vulnerability ； Risk