In order to reveal the effect of rainfall

topography

land use pattern and other factors on sediment and phosphorus loss in natural small watershed

four small watersheds with different scales (Surong

Jieliu

Daxing

and Wanan) were chosen according to the natural physiognomy and land use characteristics of small agricultural watershed in Hilly Area

and the monitoring areas were 3.0

34.6

480.3 and 1 236.4 hm2

respectively. Phosphorus loss characteristics of small watershed were monitored in three rainstorm events and rainfall erosivity (R) of these rainstorms were 1 411.5

595.7

391.4 MJ·mm / (hm2·h)

respectively. The results showed that： (1) The hydrological responses of Su Rong and Jie Liu

which were mainly residential areas

market towns and cultivated land

were faster

and the runoff peak value of these two watersheds appeared at 5 ～ 10 min after rainfall peak in the rainstorm event

while the sediment concentration peak and runoff peak appeared at 0.5 ～ 3 h behind rainfall peak in Daxing and Wanan. (2) There was a consistent significant correlation between sediment and total phosphorus (TP)

particulate phosphorus (PP) (R > 0.6

P < 0.01) in three rainstorm events

the sediment and TP loss loads were the highest in the source small watersheds (Surong and Jieliu)

the average TP loss load of Su Rong reached 0.36 kg/hm2

and the loss loads of sediment and TP of Wanan were the lowest

and the average TP loss load was 0.009 kg/hm2. (3) PP accounted for more than 50% of TP loss in the runoff. (4) The results of multivariate regression analysis showed that runoff and sediment contents could be used to predict phosphorus flux. A combination of sloping cropland

forestland and paddy field could significantly reduce the sediment and phosphorus loss load. The results could provide references for calculating the multi - scale loss of phosphorus in the rainstorm process of small agricultural watershed in Hilly area.