雨滴动能对红壤地表溶质迁移特性影响试验

Effects of Raindrop Energy on Runoff,Chemicals and Sediment Transport in Red Soil Slope

以非吸附性溴离子和吸附性磷元素为示踪剂,通过改变针头式降雨器的雨滴降落高度获取不同雨滴动能,并推算其相应的雨滴能量流(Rain droplet energy flux,DE),研究雨滴动能对红壤坡面溶质迁移特征的影响。试验结果表明,初始产流时间、地表土壤含水率、土壤水分入渗深度等均随着DE增大而线性减小;径流总量(Total runoff,TR)与DE呈幂函数递增关系;产沙量(Sediment yield,SY)与DE可用对数函数描述。在不同雨滴动能条件下,径流溴离子浓度随产流时间呈幂函数衰减,土壤溴离子淋溶深度随着雨滴动能增大而减少;径流溶解态磷浓度随产流时间呈线性增大趋势,径流全磷(Total phosphorus,TP)流失总量与DE的关系可用指数函数描述,且径流全磷流失量与径流总量及产沙量高度相关;雨滴动能越大导致表层土壤磷素含量越低。

Kinetic energy from rainfall is one of the most active factors impacting soil chemicals transport in runoff and the chemicals transport by rainfall splash is usually the first step. Effects of raindrop kinetic energy on the transport of soluble chemicals and sediment to runoff and infiltration into a clay red soil were quantified. The runoff,chemical and sediment transfer were investigated in small soil beds for five kinetic energy of raindrops obtained by varying heights of fall（ 0,0. 7,1. 0,2. 5 and 4. 0 m）,using a drip-type simulator. Runoff lag time,water content in surface and depth of water infiltration decreased linearly with increasing of the droplet energy flux（ DE）. The relationships of total runoff（ TR）,sediment yield（ SY） and DE were described by power and logarithmic functions,respectively. The bromide transport in surface runoff was best described by a power decay model with the decay coefficients related to rainfall energy. The concentration of dissolved phosphorus in runoff increased linearly with time and the relation between the amount of total phosphorus（ TP） loss to runoff and DE was an exponential function. The vertical transport of bromide and phosphorus within the soil matrix was strongly dependent upon the raindrop impact.