極端水文事件土砂量對陳有蘭溪河川型態演變影響分析

Abstract

The total sediment yield from the 1999 Chichi earthquake to Typhoon Morakot in 2009 in the Chenyoulan River watershed is around 158.1×106 m3. The excess sediment yield has resulted in serious sediment deposition, widening river width and river meandering in the Chenyoulan River. By comparison of DEMs from 2004 and 2010, sediment deposits are obvious at the convergences of the tributaries and the in main river. Especially apparent are the deposited depth of 2.9 m at the convergence of the Junkeng River and the main river and the deposited depth of 2.6 m at the convergence of the Shibachong River and the main river. The serious sediment deposition has also resulted in river meandering and serious scouring upstream from the convergence of the Shibachong River and the main river, and widening river width and scouring in the main channel downstream from the convergence of the Shibachong River and the main river.陳有蘭溪集水區由1999 年集集地震至2009 年莫拉克颱風約產生158.1×106 m3 土砂量，巨量土砂產出在主河段造成河段淤積、拓寬及擺盪；以2004 年及2010 年DEM 比較結果，支流匯入溪處是主要土砂堆積處，又以郡坑溪匯入處之淤積2.9 m 及十八重溪匯入處之淤積2.6m 為最；受土砂淤積影響，在十八重溪上游匯入處上游河段以河道擺盪及河岸淘刷為主，在十八重溪匯入處下游河段則以河道拓寬及主深槽刷深為主