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

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 filters.