Linking Landscape Characteristics Of Watershed And The Water Quality Variation

Water quality of river is influenced by natural environment and human activities in river basin, the latter of the two factors, especially the change of the land use, is the major factor to the deterioration of the water quality. Therefore, it has significant academic and practical meaning to the management of the river pollution and water protection so as to investigate the change of the water quality in aspects of land use and the change of its sight. In this paper, the upriver drainage basin of MiYun Reservoir is selected as the research object combined with the water quality monitoring. The temporal and spacial diversities of the nitrogen and phosphorus overflow, and the influence of the landscape characteristics of drainage area to the disuse process of the nitrogen and phosphorus have both been analyzed through the distill of the land use and sight characteristics in the drainage area. The main conclusions are as follows:1)The land use data of the MiYun County of 1991,1998 and 2002 are abtained through the explain of the TM image, the dynamic change in 8 years and the inner driver of the image are analysized. The common portraits of the three periods are as follows: Forest land area accounts for absolute dominance(more than 50%) in which the forest land area take the largest proportion, the Cultivated area rank second of it , and the land used for City and country, factory and inhabitation and the unused land are comparatively small.The Contrast result shows as follows: there are some obvious changes in the layout of the land use in 8 years. The inner structure of the forest and cultivated land has obvious changes, The unused land and the cultivated land area reduce to a large extent while the garden plot, residential area, the factory land and forest land area increased accordingly.2) The nitrogen and phosphoru overflow of the upriver drainage area of the Miyun Reservoir show obvious spacial and temporal differences.As the result of the investigation, the nitrogen and phosphoru overflow of the upriver drainage area of the Miyun Reservoir are higher than that of the other period.We can see from that, the Chao river and the Bai river are higher than the other rivers whether in the aspect of nitrogen or phosphoru. The reason of it lies in the fact that the Chao river and Bai river are higher than the other seasonal rivers whether in the aspect of river area, the ambient population density and the intensity of the land use.Sight diversity index has no obvious correlation with the density of the nitrogen and phosphoru according to the Pearson correlation analysis of the sight characteristics index of five typical small drainage area, which reflects the fact that the form process.Of the non-point recourse pollution rest with the spacial layout of every sight types other than the number of the sight types in the drainage area and the influence of the essentiality.3) If there are "sink" sight types in the exit of the drainage area or near the water, the nitrogen and phosphorus flowed from the "source" sight will be effectively stopped By the "sink"sight, so the final non-point contaminants arriving at the water will be very limited even there are more "source" sight types in one drainage area.So there are not obvious correlative relations between the relative importance of the sight types in the drainage area and the non-point pollutants .4) The relativity of the sight factor and the water quality factor of river have the enhanced trend, among which the correlative relation of the break index and the overall thickness of nitrogen and nitration nitrogen are obvious; the thickness of the overall nitrogen, nitration nitrogen and ammonium nitrogen break shows obvious positive proportion among the rainy season and after the rainy season while it's not obvious before the rainy season. There are no obvious relations among the thickness of the overall phosphor and the break.5) There are obvious linear negative relativity among the proportion of the forest and grass land before the rainy season, in the middle of the rainy season and after the rainy season and the thickness of the overall nitrogen. The nitrogen and nitration nitrogen increase as the increase of the cropland. The thickness of the overall nitrogen and nitration nitrogen increase as the increasement of the cropland; The drainage area and overall nitrogen thickness shows negative relativity while the nitration nitrogen doesn't show obvious regularity.