Estimation of adsorbed nitrogen pollution load by soil erosion in Biliu river basin based on spatial grid unit

Integration of universal soil loss equation with sediment delivery and nitrogen enrichment model supporting by ENVI and ArcGIS system, an universal calculation method of absorbed nitrogen load was established based on spatial grid unit.Illustrated by the example of Biliu river basin, the calculation factors of the models were studied, the amount of soil and sediment loss and the pollution load of absorbed nitrogen was estimated with the sampling data and collection information.The result showed that, the average soil erosion module of Biliu river basin was 1137 tons/(km²·a), the average sediment delivery modulus was 295 tons/(km²·a), the loss of adsorbed nitrogen module was 326 tons/(km²·a) in 2012.The total loss of adsorbed nitrogen was 878 tons, forest and arable land together accounted for 64% and 32%, which forest was 562 tons and arable land was 285 tons respectively.In order to reduce the loss of absorbed nitrogen because of soil erosion in Biliu river basin, one should improve the quality of forest and grassland, and implement protection projects in weak water and soil conversation areas.