Spatio-temporal Variation Simulation Of Non-point SourcePollution In Upper Reach Of Yangtze Basin Considering Precipitation And Terrain

Monitoring data indicates that non-point source (NPS) pollution, which is increasingly serious, has become the primary factor that causeseutrophication and water deterioration in some catchments of upper reach of Yangtze River Basin.This paper selecting upper reach of Yangtze River Basin as studying area,sets updatabases of studying area. Field tests of "precipitation-runoff-pollution" will be carried out in typical plots, and the correlations between key factors (precipitation as well as terrain) and the loss ofNPS pollution will be established. Then a macro-model considers precipitation and terrain will be developed on the bases of the existing export coefficient model.The model will simulate the spatial distribution of NPS pollution more accurately. The study will represent the spatio-temporal variation laws of NPS pollution loadingfrom 1960a to 2003 a, to explore the variation characteristics of main pollution sources with the change of time, and its evolving law of spatial distribution. The main conclusions are as follows:1) Established the correlations between key factors (precipitation as well as terrain) and the loss of NPS pollution.2) The data simulated in 1960a,1970a,1980a,1990a,2000aand2003a are selected. Those of TN are 6.892×105 t,1.0281×106 t,1.1129×106 t,1.8898×106 t, 2.3184×106 t,2.4661×106 t. and as well as those of TP are 9.50×104 t,9.71×104 t, 16.41×104 t,18.18×104 t,24.04×104 t,23.96×104 t.3) Itindicates that replacing natural facts, the human activities, such as rural life,livestock and especially the unnatural land, have become the main contributor of NPS pollution since 1980a.4) During 1960-2000, thegross load andload intensity of TN and TPincreased rapidly, but after 2000 years its growth rate slowed because of the government policy. The loads of NPS pollution in dry land is high after 1980a.Theabove results showed that some measures such as water-soil conservation and farmlandto forest should be strengthened.5) For water and soil conservation as well as water environmental protection of studying area, the suggestions are carrying out the way of conservation tillage and turning slope cropping into contour cultivation, controlling fertilizer consumption, returningfarmlandto forestto keep soil and water, and lessening N、P emission of domestic animal breeding.