圖書典藏及影音數位平台

東河溪位於苗栗縣南庄鄉，為中央管河川中港溪流域支流。本溪發源於加里山山脈之鹿場大山，經由鹿場向北流至大東河再折西流至南庄，至南庄鄉公所與南來之南河溪?流而成南庄溪。東河溪全長約21.5公里，流域面積約80.8平方公里，河道坡度約1/19，屬山地型急流河川。東河溪治理範圍自加拉灣橋至南河溪?流處止約5.67公里。 本溪自民國88年由苗栗縣政府辦理治理規劃，至今尚未辦理治理基本計畫公告，且期間歷經民國88年921大地震及數十次颱洪，河道地形及周邊環境均有變化，為配合河道地形環境變化及社會發展需求，擬分2年(民國99年至100年)辦理中港溪流域支流東河溪治理規劃檢討。

The Dung-he River is located in the Nan-Jhuang Township of Miaoli County and is a tributary of Jhong-Gang River. The catchment area and the reach length of Dong-He River are about 82.36 Km2 and 21.50 Km, respectively. The original improvement planned by Miaoli County Government in 1999. The purpose of this work is to survey current condition and to collect basic data for re-evaluation waterway boundary originally established, by considering hydraulic condition and safety and right of general public. After evaluation, a new river boundary shall be established in order to be the bases for river management and for future flood control works. This study uses the dimmensionless unit hydrograph method to estimate peak flood of the river system. The 25-year return period flood at the Dong-He River outlet is 1,448 m3 per sec. The river design standard has to deliver 25-year return period flood safely. The Dung-he River is a high hill drainage system. It relies on gravity grainage. Therefore, to maintain suffucuent river section is the most important issue. The river protection standard adopts 25-year return period flood as the designed flood. The river bank height is designed according to 25-year return period flood and plus the height of free board is 1.0 meter. The coverages of this project include the embankment of protection works along the main stream of the Dung-he River between Section No.5 and No.8, the total length about 320 meter. The total engineering cost is about 16,870,000 NT$. The overall engineering benefit cost ratio is 0.18.