土壤学报2016，Vol.53Issue(2)：365-374,10.DOI:10.11766/trxb201504280138
放水冲刷对红壤坡面侵蚀过程及溶质迁移特征的影响
Research on Sediment and Solute Transport on Red Soil Slope under Simultaneous Influence of Scouring Flow
摘要
Abstract
The subtropical red soil hilly region in South China,rich in hydrothermal and soil resource, is one of the most important grain production regions,playing a key role in development of the agricultural economy of the country. With the economy developing so fast,human activities in the region are getting too intensified,leading to destruction of large tracts of natural vegetation and consequently,declining soil and water conservation capacity. Abundant rainfall in the region causes large volumes of surface runoff eroding the thin soil layers on the slopes,which not only results in soil nutrient loss and soil quality degradation, but also brings about serious environmental problems in the lower reaches of the river valleys. Therefore,it is imperative to develop researches of mechanisms of the soil erosion and nutrient translocation for conservation of the red soil resources. In order to understand influences of shallow clear-water flow scouring on soil erosion and solute transport,a laboratory scouring experiment,designed to have three scouring inflow rates(10 L min-1, 15 L min-1 and 20 L min-1),was conducted on artificial slopes of red soil derived from quaternary red clay and effects on the transport processes of non-sorbed chemicals(bromine)in runoff and sediment during the processes of soil erosion caused by surface runoff were evaluated. Results show that flow velocity of the runoff on the slope surface increased with increasing volume of the incoming flow from the upper slope;no matter how the flow conditions were in the upper slope,runoff yielding rate increased rapidly at the initial water releasing stage and then tended to level off;an apparent linear relationship was observed between cumulative runoff volume and duration of runoff yielding;when water flew down at a rate of 10 L min-1,15 L min-1 and 20 L min-1 from the upper slope,the cumulative runoff volume reached 263.2 L,295.1 L and 291.04 L, respectively;the higher the volume of the flow from the upper part,the stronger the scouring effect of the sheet surface runoff:sediment content in runoff fluctuated sharply with time,especially at the initial runoff scouring stage(0~5 min);when water flew down at a rate of 15 L min-1,sediment yielding rate dropped drastically with time,whereas when water flew down at a rate of 20 L min-1,sediment yielding rate displayed a trend of rising first and then declining;20 L min-1;cumulative sediment volume changed with time, showing a power function relationship;the cumulative sediment volume when water flew down at 15 L min-1 and 20 L min-1 was 1.42 times and 4.25 times that when water flew down at 10 L min-1,respectively;at the initial runoff scouring stage(0~5 min);the higher the water flow rate,the higher the sediment content n runoff;sediment content in runoff varied with time in a pattern similar to that sediment yielding did in and sediment yielding rate decreased gradually with the time going on regardless of how the flow rate was. Concentration of bromide decreased as a power function of the duration of runoff-yielding;especially at the initial 4 minutes of runoff scouring,concentration of bromide decreased significantly. All the findings indicate that the loss of soil solute with surface runoff depends mainly on degree and time of the interaction between soil and runoff. Based on the comparative analysis of effects of water flow rate from upper slopes on variations of volume of runoff,sediment content in runoff and soil solute in runoff with time,it is concluded that both runoff and sediment productions vary in a wavy pattern no matter how the water flows;the higher the water flow rate, the higher the runoff yielding rate on the slope. Sediment yielding rate acts differently. It is quite flat in fluctuation when the water flow rate is low,fluctuates drastically at the initial runoff yielding stage when the water flow rate is and tends to level off when erosion gullies gradually develop in shape. Cumulative sediment volume is a power function of cumulative runoff volume. Concentration of soil solute in runoff displays a similar relationship with duration of runoff production,regardless of how water flow rate is. Variation of soil solute concentration in runoff can be divided into two stages:rapid decline at the initial runoff yielding stage(0~5 min)and slow decline to a low value after 5 min. Through fitting with equations,it is found that the equation of power function can be used to describe the characteristics of solute attenuation in runoff. The findings of the experiment have some great practical significance to effective prediction and control of soil erosion on red soil slopes and soil nutrient loss with the erosion.关键词
红壤/放水冲刷/坡面侵蚀/泥沙/溶质迁移Key words
Red soil/Runoff scouring/Slope erosion/Sediment/Solute migration分类
农业科技引用本文复制引用
马美景,王军光,郭忠录,蔡崇法..放水冲刷对红壤坡面侵蚀过程及溶质迁移特征的影响[J].土壤学报,2016,53(2):365-374,10.基金项目
国家自然科学基金项目（41401303）资助 Supported by the National Natural Science Foundation of China （）
