圖書典藏及影音數位平台

*本計畫係針對缺乏護甲層之河段，探討並研擬其治理對策，並以第三河川局轄管河川(頭汴坑溪一江橋下游、大坑溪逢甲橋下游及大甲溪梅子護岸)為例，提出具體之保護工法，供第三河川局作為河防設計及施工之參考。

Due to the extremely climate change, the huge rainfall and amounts of damage flood events which let waterlevel or discharge excced conservation projects occurred frequently during flood period in these years. Furthermore, the strata were uplift induced by thrust of the 921 Earthquake (Chi-Chi Earthquake). The strata were easly to erosion and destroy by water mechanisim, here we called such strata as Weak Rock or Soft Rock. As mentioned above, such rock were take place in many riverbeds at Da-An, Da-jia and Wu River and its watershed. Such rock let the riverbeds deeper than deeper as high discharge or velocity comes up. In the meantime, every flood may caused serious destruction to the embankments, revetments and other conservation projects. Which repeatedly damages and its repaire plans were consumed disaster management resources and personnel time to deal with such situations. The purpose of this study this year is to straighten out the main problem and resolve the susceptible reaches in Wu river. (The susceptible reaches are (a)Feng-Chia Bd.；(b)I-Jiang Bd.；(c)Jian-Ming Bd. to Zhu-cun Bd.section.；(d)Fu-Xing Bd.；(e)Gan-Feng Bd.；(f)Fen-Yuan to Ton-An-Cuo embankment.) In this project, first of all is to arrange, investigate and comprehend with sediment income, watershed hydrology, channel hydralulics, geological structure, erosion, deposition, and susceptible reasons in susceptible reaches. Second, here use RESED2D model to simulate the hazards potential by different frequency rainfall periods (2yr、5yr、10yr、20yr、25yr、50yr and 100yr) and to scheme out some effective regular plans. The simulation results show that, the mean year erosion depth is (a)0.21m；(b)0.62m；(c)0.33m；(d)0.38m/0.99m. The bank recessional distances for Fen-Yuan and Ton-An-Cuo embankments are 20.9m and 19.5m.