Predicting soil erosion and deposition on sloping farmland with different shapes in northeast China by using 137Cs

•Impacts of slope shapes on the spatial variation of soil erosion were investigated by using 137Cs.•The relationships between slope shape and soil erosion rates were established.•The soil erosion rate fluctuates with slope length periodically.•The change in the soil erosion rate with slope length in a straight slope shape can be described by the cosine function.•To provide theoretical reference for soil erosion control on sloping farmland with different slope shapes.