Environmental Effects Of Land Use And Cover Change On River Systems In Huangpu River Catchments

Shanghai's high-speed development has offered the spacial structure of the metropolis a great change, and has enhanced the pressure on the entironment by waste water and waste continuously. These changes have brought water quality of Shanghai river systems significant negative influence. On the earth's surface, intense man-made reconstruction is showed by the mode of LUCC (land use and cover change). Pollutants are transported through runoff or civicism pipe-systems, then drop into Huangpu River anabranches, and at last converge to Huangpu River trunk-river step by step. So the spacial characters of the pollutants in overlying water of Huangpu River could reflect the degree of LUCC and the degree of man-made earth's surface reconstruction. According these, the thesis took Shanghai City which was reconstructed intensely, and Huangpu River which is densely covered by lots of rivers as study objects, to know the status of pollutions on Huangpu River systems and the reasons of being polluted. Using GIS catchments analysis methods, based on catchments, the thesis analyzed the relationships between the types of land-use and pollution concentrations at the controlling points of sub-catchments, estimated the exports of non-points nitrogen and phosphorus reasonably, and discussed environmental effects of LUCC on river systems. It will provide effective decision supports theories to the development of land-use in the areas where there are many human activities.Based on land classifying system for national land-resource remote sensing investigation, combining with the management character, utility models and covering character of land resource, land-use status of study area, dynamic inspection and requirements, the thesis classified the land-use on study area into six varieties, agricultural land-use, greenbelts, denizen land-use, industrial and traffic land-use, water area and non-utilized land. Through folded operation of land-use maps and Huangpu River sub-catchments map, the area and the area proportion of each land-use for each period in each sub-catchment is obtained. Through calculation of land-use levels in each period of study area, the thesis analyzed the land-use degree and its trend of Huangpu River catchment. It is found that, the sub-catchments where there are more denizen land-uses and industrial and traffic land-uses, have more obvious urbanization, and more obvious of the increase on land-use degrees.Through the analysis of water quality datas along Huangpu River, it is found that, from the headstream to the end of Huangpu River, the water quality fell obviously, and there is a great difference between areas. And deducing from water quality of years, pollutions in city area are mainly aroused by industrial waste water and denizen sewage, and the pollutions in suburb are mainly aroused by village corporation waste water, agricultural sewage, living sewage, also the sewage from birds and livestocks. The effect parameters of Huangpu River environment could be generalized into natural parameters, human parameters, land-use parameters, shipping pollutions and river sediments pollutions. Through chief element analysis, it is found that, land-use parameters are one of the most important parameters to affect rivers environment.Using the datas of nitrogen and phosphorus at controlling points of each sub-catchment and the land-use degree of related periods, the thesis analyzed the relationships between the concentrations of nitrogen and phosphorus in Huangpu River catchment river systems and land-use. It is found that, there are significant positive linearity relationships between the concentrations of TN and TP and proportion of agricultural land-use area, and it is mainly because that there are more fertilizers and the agricultural land is corroded easily. Significant positive linearity relationship exists between the concentration of NH₄⁺-N and proportion of industrial and traffic land-use area, while significant negative linearity relationship with the proportion of greenbelt area. Also there is significant positive linearity relationship between each pollutant concentration and proportion of denizen land-use area.Through estimating the exports of nitrogen and phosphorus of unit-area in each sub-catchment, it is found that, the exports of TN from the sub-catchments are more, where there are more agricultural land-uses. The exports of TP from the sub-catchments are more, where there are more agricultural and denizen land-uses. In the recent ten years, from more than half sub-catchments in Huangpu River catchment, the exports of TN are decreasing, and the exports of TP are decreasing. Also, the total exports are decreasing. The thesis based on correlation analysis, knew more relationships between LUCC and the varieties of TN and TP exports in Huangpu River catchment. There are significant positive linearity relationships between the varieties of TN and TP exports and the varieties of agricultural area proportion, while there are negative linearity relationships with the varieties of industrial and traffic area proportion. In Huangpu River catchment, along with the improvement of land-use, thecontrol and treatment system for the pollutions will be perfect, so the pollutions to the Huangpu River will be reducing continuously.