Surface pollution is the main threat to water quality of Danjiangkou Reservoir.In order to analyze the amount and form of surface pollution in Danjiang-Hanjiang watershed in Shaanxi Province

a study was carried out

and the amounts of the main surface pollutants transported into the rivers and their contribution rates were calculated using the methods of statistical investigation

parameter calculation and comparison analysis.The results indicated that the annual amounts of CODcr

ammonia nitrogen

total-nitrogen

and total phosphorus transported into the two rivers were 103 053

19 851

213 453 and 39 838 t respectively.Domestic sewage

human excrement and urine are the main source of CODcr pollution.Soil and water loss is the main source of nitrogen and phosphorus pollution.The amounts of surface pollutants transported into rivers are related to the factors such as pollution sources baseline

pollutant contents and pollutant scatter degree.It is suggested that more efforts should be invested in soil and water conservation

new countryside construction and extension of ecological and clean small watershed

etc.