扇平溪及無名溪之泥砂推估與濱水帶設置

Estimating Sediment Yields and Establishing Buffer Strips of Riparian Vegetation Zones on Sanpin and Wumin Creeks

10.29995/JSHR.201106.0006

林壯沛(Jaung-Pey Lin)；盧惠生(Hui-Sheng Lu)

集水區經營 ； 泥砂 ； 濱水帶 ； 緩衝區 ； Watershed management ； Sediment ； Riparian zone ； Buffer strip

坡地防災學報

10卷1期（2011 / 06 / 01）

59 - 72

繁體中文

本文是以六龜試驗林扇平溪及無名溪之集水區為研究對象，利用數值地形模型DTM與衛星影像資料，探討森林集水區之泥砂產量，並劃設溪流濱水帶之相關區位，冀望對水土資源保育能有貢獻，所得成果可做為六龜試驗林經營在防治泥砂之參據。扇平溪及無名溪屬荖農溪東邊的支流，為林業試驗所六龜試驗林的一部份，土地利用以天然闊葉林與人工針葉林為主，偶爾有小面積的崩塌地。扇平溪集水區面積為422ha、無名溪為115ha，地形為東北往西南走向，地勢陡峻，平均坡度超過60%。扇平地區年雨量為2,280~3,170mm，雨量豐沛，降雨量的84~88%集中在夏季。年泥砂產量換算成土壤沖蝕深度，扇平溪及無名溪集水區分別為1.3mm、2.3mm，與臺灣重要水庫集水區之泥砂產量，換算成沖蝕深度1.6mm~7.9mm相比，沖蝕並不嚴重。為保持溪流水質清淨，除了溪流兩旁嚴禁開發利用，設置40m寬濱水帶植生緩衝區，單位緩衝帶面積可減少泥砂量56.08ton/ha/yr，減少總泥砂產量45.39%。在安定河岸與河川生態保育，能有效控制非點源的污染。

The forest watersheds on Sanpin and Wumin creeks are selected as the research objects of this study. It is studied to probe into sediment yield by utilizing topographical model DTM and satellite images, and tries to draw the relevant position of riparian vegetation buffer strips to contribute on water conservation. The result will be provided for ecosystem management on Liuquei experiment forest. Drawing and setting up riparian vegetation buffer strips can be help for preventing and curing sediment yield in experiment forest management. Sanpin and Wumin creeks are eastern tributaries of Laonung creek. The watersheds are part of experimental forest of TFRI. Most of landuses are nature hardwood forest and conifer plantation, and only a few areas are landslides. The area of Sanpin and Wumin watersheds are 422ha and 115ha respectly. Topography is steep with southwestern aspect. The average slope is over 60%. Annual rainfall was 2,280~3,170 mm, and most of rainfall (84~88%) concentrated in summer time. Annual sediment yields in depth of Sanpin and Wumin watersheds are 1.3 and 2.3 mm, respectively. Sediment yields in depth in Sanpin and its branch watersheds are less than those (1.6 mm~7.9 mm) in major reservoirs of Taiwan. For promoting stream water quality, it is necessary to forbid landuse development on riparian zones. To establish 40 m in width for buffer strips of riparian vegetation zone which decreases 56.08 ton/ha/yr of unit sediment yield and 45.39% of total sediment yields, is a good method to control nonpoint pollution of soil losses from uplands, maintain stream bank stabilization and available to improve ecological function in stream.