神木集水區土壤沖蝕特性

Preliminary Study on Soil Erosion Caused by Rainfall in Shenmu Watershed

何幸娟(Hsing-Chuan Ho) ； 林伯勳(Bor-Shiun Lin) ； 冀樹勇(Shu-Yuon Chi) ； 尹孝元(Hsiao-Yuan Yin) ； 施美琴(Mei-Chin Shih) ； 羅文俊(Wen-Chun Lo)

《中華水土保持學報》 43卷3期 (2012/09) Pp. 275-283

https://doi.org/10.29417/JCSWC.201209_43(3).0008

摘要

本文透過現場時雨量及相關地文資訊，搭配土壤流失經驗公式探討神木集水區年土壤沖蝕量與單場降雨事件引致土壤沖蝕量之差異程度。同時，於現地設置多處沖蝕針監測土壤沖蝕深度，探究累積降雨量與實際沖蝕量變化關係。根據MUSLE分析莫拉克颱風事件引致土壤沖蝕量結果得知，出水溪與愛玉子溪兩子集水區於該場事件下引致沖蝕量佔全年土壤沖蝕量15％以上，顯示在降雨延時長且累積降雨量大情況下，可能誘發兩子集水區產生大量非點源土砂料源。此外，透過現場沖蝕針監測資料顯示，當子集水區遭遇累積雨量大於200mm事件下，其新增土壤沖蝕深度將快速增加，並且以愛玉子溪之沖蝕深度較出水溪高；惟因出水溪集水區面積較愛玉子溪集水區大約2倍，故就整體沖蝕量體而言，仍以出水溪集水區較高。經驗公式推估結果與現地監測資料觀察現象相符。

關鍵字

神木集水區 ； 土壤沖蝕 ； 降雨特性

並列摘要

This study uses hourly rainfall data, physiographic data, and the USLE and MUSLE soil erosion models as well as on site erosion pin studies to identify soil erosion rates within Shenmu watershed. Results from the MUSLE model revealed single storm erosion resulting from high rainfall intensity, and long duration rainfall events such as typhoon Morakot, can generate large volume non-point sources of sediment that is estimated to account for over 15 percent of annual erosion depths. Erosion rates measured at soil erosion pin studies revealed erosion depths were actually greater in the Aiyuzi watershed and erosion rates drastically increased once accumulated rainfall exceeded 200mm. Although measured erosion depths were higher in the Aiyuzi stream, because the area of the Chushui watershed is twice that of the Aiyuzi watershed, estimated total erosion volume based on field measurements was higher in the Chushui watershed, matching the results of the USLE model.

並列關鍵字

Shenmu watershed ； soil erosion ； rainfall characteristics