Downstream Risk Analysis of Magat Dam Breach Using Geographic Information System and HEC

基於地理資訊系統（GIS）與HEC的水壩潰壩後下游水域風險分析－以菲律賓Magat Dam為例

Cris Edward F. Monjardin ； Francis Aldrine A. Uy ； Fibor J. Tan ； Aileen R. Altecin ； Lois Kristel R. Apolinario ； Edhel Ann C. Peregil

《台灣水利》 68卷1期 (2020/03) Pp. 15-25

https://doi.org/10.6937/TWC.202003/PP_68(1).0002

摘要

Dam construction truly marked the civilization of humanity. There are wide range of benefits from dams, specifically the impoundment of water that can be used in the future, nevertheless it coexist with the tragic consequences of disaster such as breaching. Over the last decades, there has been a significant increase on dam failures because many dams were not designed to carry that much volume of water when built, yet, they experienced rapid unusual and severe rainfall intensity unexpectedly. It is therefore a necessity to predict a peak discharge as well as the warning time at given location, so that the early warnings could be given to downstream area residents, this must be done in order to mitigate the possible damages caused by a dam collapse. To achieve this, latest technology involving geographical information system (GIS) and computer modeling software were used in the simulation of the hypothetical failure of Magat Dam, one of the largest dams in the Philippines built 36 years ago. Through the materials produced in this study, such as flood hazard and risk maps, effective and more reliable emergency plans and early warning system design were derived. In this study, it was found that the existence of Maris Dam, around 5 kilometers from Magat Dam, impeded most of the flood. This largely increased the evacuation time for the downstream area residents, thus decreasing the risk.

關鍵字

Impoundment ； Magat Dam ； Dam Breach ； Risk Assessment ； Flood Risk Map

並列摘要

大壩建設可以說是人類文明的標誌之一。大壩可以為人類文明帶來許多好處，尤其是可以支撐未來用水的大量蓄水。儘管如此，大壩也往往會伴隨嚴重的災難性事件，例如潰壩。過去幾十年間，由於早年的大壩設計並不足以承載大量的蓄水，在經歷許多異常嚴重的降雨以及儲蓄的水量後，大壩的毀損情況不斷增加。因此，必須預測及提供相應地點的排放峰值及警示時間點，以便向下游的居民發出預警，以減輕因大壩崩潰而可能造成的損害。為實現這一目標，最新技術如地理資訊系統（GIS）和電腦建模軟體等被用以模擬預測已有36年歷史、菲律賓最大水壩之一的Magat Dam的假設性潰壩。通過本研究產生的資料如洪水災害和風險圖等、可以衍生出更高效可靠的應急計劃與警示系統設計。同時本研究發現，在距離Magat Dam約5公里的另一個水壩Maris Dam，其存在可阻礙大部分洪水，因而可增加疏散下游地區居民的時間，從而降低災害損失。

並列關鍵字

水庫 ； Magat Dam ； 水壩潰壩 ； 風險評估 ； 洪水風險圖