城市高羊茅草坪绿地水沙调控效应

通过人工模拟降雨试验,研究了60%覆盖度城市高羊茅草坪绿地(种草当年)在不同坡度(5°,10°)、不同雨强(30,60,90mm/h)条件下的产流、产沙过程以及径流携带泥沙的作用机制,并用裸地作为对照,同时定量化分析城市高羊茅草坪绿地的水沙调控作用。结果表明:(1)高羊茅草坪绿地能够有效延缓初始产流时间,但随着雨强及坡度的增加其延缓效果降低,当雨强90mm/h、坡度10°时草坪绿地几乎没有延缓初始产流时间的效果;(2)各试验条件下高羊茅草坪绿地与裸地产流率差异性显著,但雨强90 mm/h、坡度10°时二者差异性不显著;(3)各试验条件下高羊茅草坪绿地总径流量是裸地的0.8倍左右,总产沙量是裸地的1/244.68~1/28.34倍;(4)60%盖度城市高羊茅草坪绿地能够有效削减径流量和土壤侵蚀量,但削减程度有差异,雨强为30,60,90mm/h时草坪绿地的平均减流效益分别为33.23%,23.04%,13.78%,在各场次降雨条件下减沙效益均可达95%以上;(5)试验条件相同时,高羊茅草坪绿地和裸地的径流挟沙能力有差异,同一径流量下草坪绿地的土壤侵蚀量远远低于裸地;(6)分别建立城市高羊茅草坪绿地、裸地的径流量与泥沙侵蚀量之间的水沙关系。

A Study on the Effects of Urban Festuca arundinacea Grassland on the Regulation of Runoff and Sediment

Through artificially simulated rainfall experiments,we studied the regularities of the runoff and sediment yield on slopes of different gradients (5° and 10°) under different rainfall intensities (30 mm/h,60 mm/h,and 90 mm/h) with different coverages (60％ coverage of Festuca arundinacea grassland in the first year of planting,and bare land).A quantitative study was carried out on the soil and water regulation of F.arundinacea grassland.The results showed that:(1) Festuca arundinacea grassland had a remarkable effect on extending the initial runoff time.However,such effect decreased with the increase of rainfall intensity and slope gradient.The effect on the extension the initial runoff time of grassland was not significant under rainfall intensity of 90 mm/h on the 10° slope.(2) Under different experimental conditions,there were significant differences between F.arundinacea grassland and bare land,except under rainfall intensity of 90 mm/h on the 10° slope.(3) Under different experimental conditions,the total runoff of F.arundinacea grassland was about 0.8 times as much as that of the bare land,and the total sediment yield of F.arundinacea grassland was 1/244.68-1/28.34 times as much as that of the bare land.(4) A 60％ coverage of F.arundinacea grassland could effectively reduce runoff and soil erosion,but the reduction degree was different.When the rainfall intensity was 30 mm/h,60 mm/h,and 90 mm/h,the average runoff reduction was 33.23％,23.04％,and 13.78％,respectively.The sediment reduction could be more than 95％ under different rainfall conditions.(5) Sediment-carrying capacity of F.arundinacea grassland was different from that of the bare land under the same test conditions.The amount of soil erosion in the F.arundinacea grassland was lower than that of the bare land under the same runoff conditions.(6) The relation between runoff and sediment was established for F.arundinacea grassland and bare land.