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    广西桂林漓江滨岸带植被对地表产流产沙的影响

    Influence of riparian vegetation on surface runoff and sediment in Li River of Guilin City

    • 摘要: 降雨及其产生的地表径流是造成水土流失的主要原因之一,水土流失所带来的河床抬高、水质污染等环境问题亟待解决。本文通过广西桂林漓江滨岸带内建立的7 个试验小区,在汛期内观测自然降水条件下各小区的产流产沙情况,研究漓江滨岸带内植被对地表产流产沙的影响,从而为漓江水土流失防治以及面源污染治理等问题提供参考。结果表明:1)植被覆盖能显著拦截坡面径流、沉积泥沙,且植被盖度愈高拦截效果愈显著;2)在草本覆盖处理中,狗尾草植被覆盖处理截流减沙效果较其他几种草本植物覆盖处理好,可作为漓江滨岸带裸露退化区域优先选择的植物种;3)纯草本植物配置的植被带截流减沙效果优于草灌相结合配置的植被带;4)地表径流量、产沙量与降雨量、降雨强度之间在P <0.01 水平上显著正相关,径流量与产沙量之间存在密切的线性关系。由此,采用增加裸坡坡面植被覆盖、选择狗尾草作为漓江快速绿化的草种、坡面上部建立截留措施等方式,可有效减轻坡面水土流失,缓解由水土流失带来的面源污染等问题。

       

      Abstract: Background Hydrological data in Li River showed that the distribution of its water resource was not uniformity. During the flood season a large amount of sediment along with the runoff flowed into the river due to the vegetation degradation, which caused the deposition of the river and the increasing of the river bed. The rainfall and surface runoff is one of the main causes of soil and water loss, and the accompanied environmental problems from soil erosion such as riverbed elevation and water quality deterioration should be solved urgently. Usually the external natural factors cannot be controlled, but the controllable factors such as the improvement of the surface cover and the soil condition can effectively alleviate the soil erosion on the slope. Methods In this study, 7 experimental plots were established according to the different vegetation configuration. Plots were built in vegetation strips of Li River in Guilin, Guangxi Autonomous Region, where the slope was 5°. We set the rain collecting pool in the area of plots爷outlet, which aimed to collected surface runoff flows through the plots. During the flood season we observed the runoff and sediment loss under the condition of natural rainfall, the runoff was measured through the volume method, and the sediment content was measured by the water quality analyzer in this experiment. The data were processed by Excel 2007 and analyzed by SPSS18.0 software for correlation analysis. Results 1)Vegetation significantly intercepted runoff and sediment, the higher the vegetation coverage was, the better the interception was; thus the vegetation coverage should be increased in the restoration areas, which could effectively prevent and control soil erosion. 2) The riparian vegetation covered by Setaria plicata intercepted runoff and sediment better than others, S. plicata should be preferably selected as the shore plants in bare degradation area of Li River. 3) Pure herbaceous vegetation intercepted sediment better than that of grass and shrub vegetation. However different vegetation arrangements had their respective advantages and disadvantages, during vegetation restoration we should choose different vegetation configuration modes according to the needs. 4) Surface runoff and sediment were positively correlated with rainfall and rainfall intensity at the level of P <0.01, there was a close linear relationship between runoff and sediment. Conclusions Thus, through some ways such as increasing vegetation cover on bare slope surface, selecting S. plicata as the fast green grass in Li River, establishing the interception measures on the top of slope, and so on, the soil and water loss could be effectively reduced, the non-point source pollution caused by soil erosion could be alleviated.

       

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