Abstract
Slope gradient is one of the critically important factors which drive the erosional response of microtopographic surfaces. This study investigates the effect of slope gradient on the evolution of erosion under accumulative rainfall in laboratory experiments and calculates critical slope values that help evaluate land suitability for farming and similar purposes. Dynamics of accumulative runoff, accumulated sediment and their rates in each erosion stage are studied when the slope gradient varies. The critical slope value for the microtopographic surface was calculated according to the relationship between the sediment yield and slope gradient. The amount of eroded soil downhill in each erosion stage was calculated using DEM data of point cloud. Results show that 1) a steeper slope would increase cumulative runoff; 2) cumulative sediment increases rapidly initially and then stabilizes with the increase of slope; 3) the critical slope value for the whole erosion is determined as 10°. The findings of the dynamics of interrill erosion and sediment characteristics are useful information for future research of erosion prediction and conservation of soil and water in the Chinese Loess Plateau.
Highlights
Slopping farming land accounts for nearly two-third of the total land of the Loess Plateau in China, and the average annual erosive modulus is as high as 25,000 t∙km−2∙a−1 [1]
An SPSS regression simulation predicted that the relationship between rainfall and cumulative runoff could be best represented by the Equation (1): Srunoff =b0 + b1x + b2 x2 + b3 x3 (1)
Contour tillage is a kind of soil conservation tillage methods along the contour line of topography, enhancing water infiltration and storage capacity, regulating runoff and reducing soil erosion, so as to benefit crop growth and increase yield per unit area
Summary
Slopping farming land accounts for nearly two-third of the total land of the Loess Plateau in China, and the average annual erosive modulus is as high as 25,000 t∙km−2∙a−1 [1]. There is a general consensus that contour tillage (CT), as an agricultural farming practice widely used in the Chinese Loess Plateau, has favorable soil and water conserving effect [14] [15]. The optimal critical slope for appropriate tillage remains unidentified
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