东北黑土坡耕地不同水力条件下坡长对土壤细沟侵蚀的影响（英文）

Effects of slope lengths on rill erosion under different hydrodynamic conditions in black soil sloping farmland of Northeast China

集中水流条件下细沟土壤侵蚀过程对研究细沟侵蚀机理与土壤侵蚀预报有着重要的意义,并且为土壤侵蚀模型其他重要参数比如剥蚀率、可蚀性参数提供基础数据。为了研究东北黑土坡耕地不同水动力条件下坡长对土壤细沟侵蚀的影响,该文采用室内模拟试验方法,测量含沙量随坡长的分布。试验设计包括4个坡度(5?、10?、15?、20?)与3个流量(1、2、4 L/min),在不同水力条件下,测量不同坡长(0.5、1、2、3、4、5、6、7、8m)含沙量。结果表明含沙量在各种水力条件下均随坡长增加,且其增加的速率随坡长减小。对坡长与含沙量系列数据用幂指数函数拟合,其决定系数R2在0.85到0.99之间。因此,黑土坡耕地细沟侵蚀产生的含沙量随坡长呈幂指数增加,且含沙量在一定坡长之后将达到最大值。随坡度和流量的增大,水流在更短的坡长上侵蚀并携带更大的最大含沙量。该文对进一步理解与研究细沟侵蚀过程有着重要的意义,且为深入研究细沟侵蚀提供了数据支撑,为土壤侵蚀模型剥蚀率、可蚀性参数等提供依据。

Rill erosion under concentrated water flow is important in studying the mechanism of rill erosion and predicting soil erosion and also provides a database to estimate other parameters of erosion model,such as detachment rate and erodibility.This research aims to study the rill erosion of black soil over cultivated slope to reveal that the sediment concentration varies with slope length.Laboratory simulation was conducted to measure the distribution of sediment concentration along with slope length.This experiment involved four slopes(5°,10°,15°,and 20°)and three flow rates(1,2,and 4 L/min).Sediment concentrations at different slope lengths(0.5,1,2,3,4,5,6,7,and 8 m)which determined by the distance between inlet and outlet were measured under different hydraulic conditions.Concentrated water flow was pumped to scour the soil slope from the designed inlet location to the outlet of the soil flume.Sediment-laden water samples were collected from the sediment collector when water flow run from inlet to outlet and became steady.The samples of different sediment concentrations were dried by an oven and calculated to determine the distribution of sediment along the slope length.As the experiment repeated under different hydraulic conditions,the data series of sediment concentration changed with slope length were attained.The results showed that sediment concentration increased with slope length under different hydraulic conditions;however,this increase rate gradually decreased.The data series of sediment concentration were fitted to slope length with an exponential function.The coefficients of determinations(R2)ranging between 0.85 and 0.99 showed that the exponential function could well fit the experimental data.With the exponential function and the experiment data,the maximum sediment concentration(A)and decay coefficient(B)were regressed.With the increased in slope gradient and flow rate,the water flow needs a shorter slope length to get to a higher maximum sediment concentration compared with the circumstance of low slope gradient and flow rate.Parameter sensitivity analysis was adopted to research the influential degree of each parameter on the maximum sediment concentration.The sensitivity of flow rate is higher under low slope gradient and flow rate compared with the condition of higher slope gradient and flow rate.Slope gradient exerted higher impact on the maximum sediment concentration than flow rate.The slope gradient had a greater influence on parameter A with that under lower slope gradient which means that the effect of slope gradient on A decreased with the increase of slope gradient under the same flow rate.The parameter B generally increased with the increases of slope gradient and flow rate which means sediment in water flow increased faster and need shorter slope length to achieve the maximum value.This study does not quantify the rill erosion process over black soil slope but also provides a foundation for estimating some model parameters such as detachment rate and erodibility.