Characteristics Of Watershed Of Miyun Reservoir And Loss Of Nitrogen And Phosphorus

As one of the important sources of water pollution, non-point source pollution has been attracted more and more attention, however, research work is mainly focus on the characteristic of runoff and erosion from plots or fi(?)lds, and seldom involves the moving process of nutrients and the impacts on water quality. Shixia experimental plots and upstreamr watershed in Miyun Reservoir is choosed as research areas at two different scales. At Shixia experimental plots, the loss of nitrogen and phosphorus from slopeis discussed, while the tempo-spatial variation of nitrogen and phosphorus loss and impacts of characteristics of watershed (landuse, landscape pattern, drainage density) on nitrogen and phosphorus loss at the watershed scale. The main conclusions are as followed:1) At Shixia experimental plots, concentration of total nitrogen and phosphorus are varied with different landuse, the concentrations from orchard and agricultural land are the highest, that from woodland is the lowest; No tillage can decrease the loss of nitrogen and phosphorus; flow, sediment, nitrogen and phosphorus loss in land covered with vegetation are lower than that without vegetation; the loss of nitrogen and phosphorus in higher slope is higher than that of lower slope; With high water-content, soil has high loss of nitrogen and phosphorus .2) Concentration of nitrogen and phosphorus in the water bodies of upstream watershed of Miyun reservoir has great temporal and spatial variation.At the temporal scale, the concentrations of TN and TP at rainy reason are higher than those after rainy season, and before rainy season; Concentrations of NH₄⁺- N is higher before rainy season than thoseafter rainy season and duringrainy reason due to temperature effect on its existing form. At the spatial scale, concentration of TN, NO₃^-N in Shuibaozi river and Chao river is the highest all the time; Because of the low concentration of NO₂^--N, it does not appear temporal and spatial variation; the spatial variation of TP is distinct, which is high in the sampling point near villages.3) The form of nitrogen and phosphorus loss is varied at the differenthydrological stages. Dissolved nitrogen and phosphorus is the main form in streams before rainy season and after rainy season, the ratio decreases in rainy season, particle nitrogen and phosphorus is the main...