圖書典藏及影音數位平台

大里溪流域位於人口密集之台中市，多次颱風與豪大雨之考驗，確實有效發揮防洪效果，為因應區域內人口激增、工商快速發展，流域內之堤防有必要未雨綢繆，先行瞭解堤防現況及爾後改進方向，俾保障堤內民眾生命財產安全。

The Dali river system flows through the prime locations of the greater Taichung city area, including the six streams of the Dali river main stem and its tributaries Han river, Ta-Keng river, Puzi river, Tou-Bian-Keng river and Chaohu river, the river’s downstream terrain is relatively flat, and every time there are heavy rains the area floods easily, from 1990 to 2008 this Bureau has respectively executed the first, second and third phase of the Dali river remediation project, to solve the nightmare of heavy flooding, but the riverbank protection constructions on the Dali river were built in 1989, and currently, even as some sections of the embankments are more than 20 years old, there are no major damage situations, but in view of recent climate anomalies, previous typhoon disasters are feared to have damaged the riverbank protection constructions, therefore it is recommended to use ground penetrating radars for detection, and, in order to understand the internal cavitation and subsidence situation of the embankment, this project was implemented. This project’s scope of work are the embankments from Dali river remediation project phase one, a total of 12 embankments including the left and right riverbank, total length of 29,011 meters; the results of periodic inspection show that there are 489 damaged riverbank protection construction in the project area, amongst which 8 sites needs immediate improvement, 47 sites needs focus improvement and 434 sites needs program improvement, the 8 sites that needs immediate improvements are respectively situated on the Kuang-Ming embankment (3 sites), Dinglun embankment (1 site), Xia-Tian embankment (1 site) and Yongfeng road embankment (3 sites); also, program improvement include working at 4 embankment breaches sites (Chung Hsin drainage pump station construction, Shuwanpi pumping station construction, Houshidi drainage pump station construction and Zelungpi drainage pump station construction), all restorations have been completed within the project duration. The total length of the penetrating radar detection in this project was 8,044.5 meters, inspected embankment length was 2,745 meters, and the inspection results indicate that mild cavitation length was 644 meter, moderate cavitation length was 22 meter, and currently no severe cavitation signals have been detected. Of the inspection results, moderate cavitation signals were detected at Xia-Tian embankment, Yongfeng road embankment, Yamuer road embankment and Taipin road embankment, while mild cativation signals were detected at all other embankments. After comparing the results of the ground penetrating radar detection and visual inspection, in addition to cavitation caused by holes and slope subsidence, part of cavitation area is located near crack damage areas, and it is presumed that cracks penetrated the concrete clope, rain water infiltrated along the cracks, causing the erosion of the embankment soil, thus causing cavitation signals to be detected. The total cost for full maintenance and repair expense for the riverbank protection construction most severely damaged 8 sites within the project range (Yongfeng road embankment 3 sites, Kuang-Ming embankment 3 sites, Xia-Tian embankment and Dinglun embankment respectively 1 site) is estimated to be NT Dollars 1.1 million.