Study on the Source of Soil Erosion of Forest Watershed

• Main Authors: Chia-Feng Lin, 林佳鋒
• Other Authors: Prof. Dr. Ming-Chieh Chen
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/93568877524599253239

碩士 === 國立臺灣大學 === 森林學研究所 === 89 === The purpose of this study was to sample streamflow, suspended loads and bed loads of storm events on the slopes and stream channels ,that then to understand the source of sediment in a forest watershed. Samples were collected during 1999/6 ~ 2000/12 from the Fushan Experimental Watershed No. 1 which was a subtropical board-leaved forest in northeastern Taiwan. Sediment transport rates of four rainfall events were 29 % ( Kai-tak 1 typhoon), 30 % ( Kai-tak 2 typhoon), 45 % ( Bilis typhoon), and 35 % (Xangsang typhoon), which represented that upstream sediments were paragraphed to output. And stormflow rates ( storm discharge / rainfall ) of four rainfall events were 36 % ( Kai-tak 1), 75.1 % ( Kai-tak 2), 70.5 % ( Bilis) and 76.1 % (Xangsang). Almost all watersheds became the source areas of runoff and all rainfall were responded to output of streams immediately. During the study of Bilis in the Fushan Watershed No 1, suspended loads on slopes were 17,340 kg, and suspended loads on stream channels were only 3,750 kg. Suspended loads on slopes were heavier about 13,590 kg than those on stream channels. The Fushan Watershed No. 1 has a trapezoid pool in the upstream channel. So the bed loads caused by typhoons wouldn’t output immediately, but they accumulate and then output until next storm event. However, there was a positive relationship between suspended loads and streamflow. The more surface runoff on slopes was, and the more suspended loads on slopes output. It’s the same result between streamflows and suspended loads in qualitative respect. In quantity, suspended loads on slopes were still heavier than those on stream channels.