Effect of erect grasses on sediment retention within a grass strip

in International Symposium (oral presentation paper), 國際研討會(全文口頭發表)
標題Effect of erect grasses on sediment retention within a grass strip
AuthorsWu, 吳嘉俊, Chi-Han Chiang 蔣季翰, Yi-Sin Jiang 江宜欣, Zih-Siang Lin 林子祥, & Siao-Wun Chu 褚筱雯
出版日期May 8 2008 12:0

Grass strip, part of a vegetative buffer strip, usually plays an important role in sediment and pollutant removal. There are numerous studies conducted in the past focused on different aspects of vegetation buffer strips. The main objective of this study is to experimentally investigate how single- and double rows of erect grasses affect sediment retention of a grass strip.
Experiment parameters related to this study include slope gradients, mean sediment sizes, inflow rates, and combinations of single- and double-row Guinea grass installed at the front end of a 4.5-m wide Bahia grass. Flow velocities, elevations of flow surface as well as deposited sediment within the grass strip are measured during experiments. Sediment load leaving the grass strip are also sampled continuously.
Results of this study indicate that as slope gradient increased to 15% and above, gaps between erect grass stems cause inflow to concentrate that apparently increase flow velocity, reduce sediment retention, change hydraulic characters, allow sediment to advance farther in grass strip, and shorten the runout time of sediment discharge. Double-hedge row appears to perform even worse than single row on steeper slopes. Hence, either combination of erect grass and creeping grass strip has to be used with caution; especially when water quality downstream of the grass strip is the main concern of conservation.

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