林邊溪流域河川化學性質、輸砂量與山崩之關係

Links on Chemical Characteristics, Sediment Discharge and Landslides around the Catchment of Linpien River

陳冠樺(Guan-Hua Chen) ； 陳宏宇(Hongey Chen)

《工程環境會刊》 34期 (2015/01) Pp. 97-122

https://doi.org/10.6562/JEE.2015.34.6

摘要

本文以屏東縣林邊溪為例，利用1982年至2013年的31年間之輸砂量、2005至2012年的5個颱風事件以及2013年3月至2014年4月的河水化學性質，來探討河川化學性質、輸砂量與山崩之間的關係。從輸砂量的研究中發現，這個區域的年輸砂量平均為1.40Mt。在5月至10月的濕季期間，輸砂量佔全年輸砂量97.47%。另外，颱風事件的研究中發現，這個區域颱風事件的輸砂量平均占全年輸砂量的39.02%。此意義顯示，濕季或颱風暴雨帶來的高降水因素，主導了林邊溪的輸砂特性。從颱風事件造成之崩塌地分布的分析結果顯示，輸砂量較高之2009年莫拉克颱風、2008卡玫基颱風與2005年的海棠颱風的新生率較高，顯示新發生的山崩會供應河川豐富的地質材料而提高事件輸砂量。2013年3月至2014年4月的河水化學分析結果顯示，中上游的河水化學性質陽離子來自碳酸鹽的比例最大82.33%，最少的則是大氣輸入3.85%。此意義顯示，變質岩內少量分布的碳酸鹽可提供河水，大量來自碳酸鹽的化學成分。下游新埤測站樣品的陽離子中，來自碳酸鹽的比例最大62.12%，其次為雨水14.90%，最少的為人為輸入8.23%。對林邊溪而言，每年濕季颱風事件所造成的高輸砂量與大量山崩，會持續搬運風化作用的產物，使母岩的新鮮面不斷暴露至地表接受化學風化，顯示物理風化對化學風化有重大影響。

關鍵字

林邊溪 ； 崩塌地 ； 輸砂量 ； 化學風化

並列摘要

This research utilizes sediment discharge during 1982 to 2013, 5 typhoon events during 2005 to 2012, and river chemistry during March 2013 to April 2014 of Linpien River to study the relationship between river chemistry, sediment discharge and landslide. The average of annual sediment discharges was 1.40Mt. The sediment discharge yielded during wet seasons (May to October) contributed 97.47% to the annual sediment discharge. In addition, the average sediment discharge during typhoon events contributed 39.02% to the annual sediment discharge. It implies that the high rainfall during wet seasons or typhoons controls the variations of sediment discharges of Linpien River. The analyses of landslides caused by typhoon events revealed that the higher sediment discharge of Morakot in 2009, Kalmeigi in 2008 and Haitang in 2005 with higher newborn ratio, which implies that the newborn landslides would contribute abundant sediments to the river, and results in the increase of sediment discharge of the typhoon event. The analyses of major elements from water samples collected in the basin during March 2013 to April 2014 showed the contribution of river chemistry from carbonate was highest (82.33 %), and the last was atmospheric input (3.85 %) in upstream samples. This implies the trace carbonates in metamorphic rock could influence river chemistry significantly. The cation in water of the downstream samples collected at HsinpiStation was contributed most from carbonate (62.12 %), next was atmospheric input (14.90 %), and the last was anthropogenic input (8.23 %). For Linpien River, the high sediment discharge and the massive landslides caused by typhoon events during wet seasons would transport weathering products continuously. It makes the fresh surfaces of bedrock be exposed to earth surface, and results in the intense chemical weathering. In the conclusion, the physical weathering has significant influence on chemical weathering.

並列關鍵字

Linpien River ； Landslides ； Sediment Discharge ； Chemical Weathering