Study On Land Use Change And Impact On River Water Environment In The Context Of Urbanization

The Taihu basin is one of the most developed regions in China,its water pollution occurs frequently makes the regional sustainable development in a big threat.Intensive human activities not only make efforts on its land use's structure and functional change,but also directly disturb the river healthy development and water environment system.In this context,how to find a basic flow to maintain the river normal update and coordination the human demand in water resources has become a hot issue,at the same time after understanding the status of the water environment,do the research about the response of the urbanization of land use change and river water quality,can be regarded as provide a theoretical basis for the future of urban planning and water environmental protection.The paper do the study from a multidisciplinary research perspective,integrated hydrology,ecology,landscape ecology research methods in the Xitiaoxi Basin,the main point is to about the water environment,use environmental flow as a start,combine the study about the land use,and water quality data,with ArcGIS,Canoco for Windows4.5 and other analysis software,taking into account the environmental characteristics and human activities.In the introduction of water flow calculation,we put human activities and water indicators into consideration,and during water quality evaluation,we choose using objective entropy weight to amend comprehensive water quality identification index.We make effort to know the watershed situation,land use types,variation and response pattern of the relationship between the water environment and strive to make up for the lack of research in the region,and try to give some some measures about the water quality control.(1)Analyzed the present situation of water environmentFirstly,we identified the characteristics of the water environment,using Spearman to screen the appropriate water quality indicators,finding that TN,BOD5 and DO was often quality dissatisfaction,and in non-flood days the quality is superior to flood ones.On this basis,We chose environmental flow method to evaluate the water comprehensive situation and found that Huxi and Xitiaoxi Stream was failed,and the rest of the streams were all up to standard.For Xixi,the new index weight method made it changed the result,compared to the weighted average method and the traditional method,the new objective entropy weight is more reasonable.(2)Identified the characteristics of the land use change under the urbanizationWe uesd GIS to analysis the Xitiaoxi watershed's land use data of 2001 and 2010,we found that the urban land increased rapidly,accounting from the 0.76%to 8.87%,while the forest is greatly reduced by 82.32%to 67.86%,and five sub-basin were all have the same change,like urban land increased and dry land and forest area was in a declining trend,especially Xixi's urban land suddenly increased from 0.08hm2 to 23.93hm2,and its local relative change rate is far more than the rate of change of the entire land area of the town.(3)Discussed on the relationship between urbanization land use Change and water qualityIn order to investigate response about the land use change and river basin water quality,we firstly used the GIS to obtain different spatial scales of land use type area,and then calculate the land use pattern index at different spatial scales of each sub-basin by redundancy analysis,the results show that ?the increase of urban land can make the water deterioration,but the paddy fields has the opposite effect and tthere is no seasonal differences.?land use pattern like SHDI,COHE and IJI has a negative effects on the water quality indicators except DO,while PD,SH_MN have a positively correlation with it.(4)Proposed water environment control measuresThe Xitiaoxi basin's natural present situation can be divided into part of the landscape protection area,which can weaken the non-point source pollution,such as sewage emissions.The government should speed up the installation of urban sewage pipe network,and do some further control about the pollution from urban tourism.