Investigation of Erosion Rates and Sediment Sources by Using ~(137)Cs Technique in the Loess Plateau of China

摘要

~(137)Cs reference inventories ranged between 1,652-2,741Bq/m~2 (1993s' level), and had a tendency to increase from northwest to southeast as annual precipitation increase in the Loess Plateau. The average ~(137)Cs inventories on cultivated slopes (19°-29°) ranged from 557.2 Bq/m~2 to 1,068.0 Bq/m~2 which accounted for 21.94% and 42.05% of the local ~(137)Cs reference inventory, respectively, and corresponding erosion rates ranged from 8,409.4 t/(km~2 · yr) and 4,856.6 t/(km~2 · yr), respectively. The average ~(137)Cs inventories on steep grass and forest slopes (24.1°-43.5°) ranged from 1,770 Bq/m~2 to 2,310Bq/m~2 which accounted for 68.0 % and 88.9 % of the local ~(137)Cs reference inventory, respectively, and corresponding erosion rates ranged from 136 t/(km~2 · yr) to328 t/(km~2 · yr). It was apparent that soil erosion was severe on cultivated slopes and slight on the forest and grass slopes. More than 70% of sediment in rivers comes from the gully area in the Loess Plateau region although soil erosion is severe on the cultivated slopes in the inter-gully area.