ABSTRACT
The main causes of soil erosion in the Loess Plateau are porous soil, sloping fields, and sparse vegetation. The rainwater harvesting agriculture (RWHA) was adopted for harvesting rainfall and runoff from sloping fields and gullies during heavy precipitation. Harvested water was stored in a sealed pond and used to irrigate crops in the key period of crop water demand. Sediment loss rates are the function of rainwater harvesting level, h, and sloping angle (in radians), q, of the sloping fields. There is an empirical equation: S = Kį sin q (1-h)2 where S is annual soil loss, K, is the coefficient of soil erodibility that includes soil structure, rain factor, plant coverage, which has an average value of 25 t ha'1 yr'1 that ranged from 20 to 3 0 1 ha'1 yr'1 in the experiment plots. The RWHA decreased the soil erosion for the following reasons (1) It could store the runoff and decrease sediment delivery by more than 80% in the period of heavy rainfall; (2) The vegetation could be recovered in the sloping fields because it did not need to be tilled since the better farmland could produce almost twice as much product if the crops were irrigated twice by the stored water.
