To study the loss characteristics of sediment and total nitrogen (TN) by runoff in a typical watershed of the Southern Shaanxi area under natural rainfall events

Hougou agricultural watershed was selected to examine runoff

sediment and TN in natural rainfall events of rainy seasons during 2011 to 2012. The results showed that the best regression equation was S curve equation between sediment loss flux and runoff of slope land

returning farmland

garden field

and linear functional relation was the best regression equation for orchard field. The reciprocal equation model could describe the relation of TN concentration and runoff in slope land and garden field

linear functional relation could express the relationship of TN concentration and runoff in returning farmland and orchard field. The order of sediment and TN loss flux in different land use in rainy season was: Garden field (4 011.7 kg/hm2)＞slope land (1 720.0 kg/hm2)＞returning farmland (1 606.3 kg/hm2)＞orchard field (776.3 kg/hm2)

garden field（15.29 kg/hm2）＞returning farmland（7.20 kg/hm2）＞slope land（4.92 kg/hm2）＞orchard field（1.37 kg/hm2）. The linear equation and power function equation could show the relation of runoff kinetic energy and sediment loss

and the logarithmic function curve and power function equation could explain the relation of runoff kinetic energy and TN loss. The risk of the loss of sediment and TN was the highest at the later stage of rainy season in the Southern Shaanxi area.