Study On Land Use Cover Change And It's Impacts On Flood Disaster Formative Environment In The Yangtze River Delta Region

The Yangtze River Delta Region is not only one of the largest population concentrated area in China, but also the richest and the most developed region.With the rapid progress of urbanization it has became the largest group of highly urbannizationed cities. In this region the urban land area sharply increased, which occupying great amounts of cultivated land, forestland, water area, and grassland. At the same time, it has made massive damage to the structure of river network. The flood disater and water environment issues increased. The scientific significance of this study is to clarify the effect mechanism and puts forward countermeasures.On the theoretical level, this study not only enriched the theory of flood disaster formative environment but also improved the research system of land resources and coupled with environment. The results provided a good example on reasonable use of land resource and reduce flood disaster for highly urbanized area in east China.In this study, the theory of flood disaster formative environment was put forward by induction and summary from disaster theory, environment disaster theory, and hydrology. The discussions were made to understand the dialectical relationship between flood disaster formative environment, inducing factors, and bearing body.From the remote sensing image interpretation and digitalization of related maps, a dataset was built including three diffirent time data, which is from 1991,2001, and 2008. The dataset was used to analyze the LUCC and it's driven forces by factor analysis, which conclusion was used as index of RAGA-PPC and CLUE-S combined model to simulate the land use change. The simulation used not only driven forces, but also the main factors of flood disaster formative environment. The simulation accuracy and efficiency was both improved by the benefit of dimension reduction and iteration procedures from RAGA. The impacts of LUCC on flood disaster formative environment was also analyzed in two typical areas which is Suzhou area and Lake Taihu catchment.The results showed that the formative environment was not only a factor to flood disaster but also a combination of many factors. The occurrence, intensity, and process of flood disaster were comprehensive effected by flood disaster formative environment, inducing factors, and bearing body. From the macro-view the LUCC has sharply changed, the main character showed that massive occupation of urban land to others and the underlying surface was strongly disturbanced by it. From 1991 to 2008 the urban land area of the Yangtze River Delta region has increased from 4857.08km2 to 23178.53km2, the main source of occupation were cultivated land. The result of factor analysis showed that the population and economic grows were the main driven forces of LUCC in the Yangtze River Delta region. From the medium-view the flood diversion and storage ability of Taihu Lake catchment decreased significantly, the mutual-transformation of urban land, water body, paddy field and upland field played a decisive role. From the micro-view the rivernet struture was effected by urbanization, the whole structure was simplified.The simulation results showed that the combined model improved the accuracy to 82% which improved by 5.58% as a whole and partially by 17.75%. The simulation also conclued that the congstruction land would continuous increase at, the main factors of flood disaster formative environment had a same trend, which showed the risk of flood disaster would increase, and the whole flood disaster formative environment had a trend of deteriorative.