Preliminary study on spatial distribution of soil erosion in a small watershed in purple hilly area using ¹³⁷Cs tracer

The ¹³⁷Cs contents in soil profiles were analyzed under different land use types, gradients, slope lengths, and landform positions in Xiangshuitan watershed in purple hilly area. Spatial distribution of soil erosion in Xiangshuitan small watershed was estimated. Results show that the reference ¹³⁷Cs content is 1870 Bq/m². Average erosion intensity is 4468 t/(km²·a) in cultivated land and 1759 t/(km²·a) in forest land. Erosion amount is exponentially related with slope length and gradient. Average annual soil erosion intensity in hilltop, hillside and neck are 2125, 4676, 1759 t/(km²·a), respectively. Soil erosion is significantly influenced by the land use types, slope lengths, gradients and landform positions. The cultivated land is the chief source of sediment in Xiangshuitan watershed in the purple hilly area.