漓江滨岸草带对径流泥沙的拦截效果

Preliminary study of runoff reduction and sediment removal by grass strips in riparian zone,Li River

位于污染源和受纳水体之间的滨岸带对径流泥沙的过滤作用已经得到广泛认可,滨岸植被的存在能降低径流流速,增加土壤入渗,延缓产流时间,促使径流中的悬浮物质得到沉积。而关于漓江滨岸草带过滤作用的相关定量研究和应用尚未见报道。为探索影响草带过滤效果的影响因素,在广西漓江滨岸带内按不同植被条件、不同带宽布设6个试验小区,通过小区放水试验测定滨岸草带对径流泥沙的拦截效果。结果表明:草带能有效拦截径流悬浮物,对径流、泥沙的拦截率分别达到66%和68%,当草带宽度增加到10m时拦截率均达90%。带宽是影响径流泥沙拦截的主导因素。植被条件是影响拦截效果的又一重要因素,而初始含水量和入流泥沙浓度对拦截效果的影响较小。同一草带对泥沙的拦截效果优于径流的拦截效果,且二者之间存在密切的线性关系。

The impact of vegetation on pollutant removal from runoff in a riparian zone has been widely recognized. Vegetation on the riparian zone is believed to decrease water turbulence, increase water infiltration, prolong the runoff producing time and enhance the sediment deposition through it. However, to the best of our knowledge, no study has been conducted so far to assess the performance of grass strips grew in riparian zone of the Li River. In this study, six experimental plots with varying plantation modes and vegetation lengths were constructed in the riparian zone of Li river, Guangxi Zhuang Autonomous Region, which were used to determine the effect of runoff reduction and sediment removal by typical vegetation. The results of our study showed that grass strips could effectively intercept runoff and sediment. The average runoff and sediment trapping efficiency （TE） of all six plotted filters were 66% and 68%, respectively. The trapping efficiency reached 90% when the filter length was increased to 10 m. The results indicated that the length of the filter was the most crucial factor affecting sediment deposition. Vegetation type was another important factor, and was found to be more decisive than the initial water content and inflow sediment concentration. The sediment TE was higher than the runoff TE, and appeared a positively linear relationship with the runoff TE in one and the same vegetated fihers.