好茶部落自然环境与土砂灾害之探讨

Discussion of Natural Environment and Sediment Disasters in Houcha Tribe Area

好茶部落位处台湾屏东县北端雾台乡南侧,紧邻高屏溪流域之支流隘寮南溪旁,2005-2007年接连遭逢台风暴雨使得部落周边遭受严重之崩塌、土石流与洪水等灾害。研究则以好茶部落历史灾害、环境地质、致灾情形、肇灾原因与河道蜿蜒变化。研究结果发现好茶部落周围灾害成因主要为降雨量过大、环境地质条件不佳与排水系统不良外,原河道宽度不足与河道主深槽差异致使河道纵横向刷深扩大,以及部落位处河阶堆积层,住户距河道及边坡之缓冲距离不足等因素有关。又因近年之雨季降雨量均超过年平均降雨量,致使好茶部落周边地质条件变得较为软弱,更易发生冲蚀崩塌灾害。隘寮南溪河道变迁亦为造成好茶部落酿灾因素之一;自集水区上游往下游运移之土砂,不仅抬高溪床,河道束缩段与河道蜿蜒处因洪流冲刷,使河道变迁与影响更为显著。

The Houcha tribe is located in Wutai Township, Pingtung County of south Taiwan, adjacent to Ailiaonan river of the subsidiary current Kaoping river basin. From 2005 to 2007 series of typhoons and heavy rainfall make Houcha tribe suffered serious landslide, debris flow and flood disasters. Investigate and to discuss the history of disasters, environment geology, reasons of disasters and changes of river in this research. Study found that disasters caused by the excessive rainfall, bad environmental geological conductions, adverse drainage system, narrow river cross section and different stream depth, which were made the stream deeper and serious vertical and horizontal expansion erosion. As well as this tribe located in the deposit layer by the stream side, houses close to stream bank and hillside as inadequate buffer dis- tance of such factors. Due to near 3 years rainfall data analyzed result, the annual rainfall in rainy season more than other region of Taiwan. With the result Houcha tribe was surrounding geological conditions become more vulnerable and more susceptible to erosion or landslide disaster. The sediments were transported from watershed upstream to downstream, not only to raise the stream bed, but also to change the topography, especially in narrow and curves area due to flood erosion.