Study On Land Use/Cover Change And Soil Erosion In Chaohu Watershed In Recent 20 Years

Based on the GIS and RS technology,Chaohu Watershed as the study area,Landsat satellite remote sensing image is based data analysis of Chaohu Watershed land use / cover,divided into four periods with the temporal and spatial dynamic characteristic in 1992-2013,and based on the Markov model of Chaohu Watershed in the future land use pattern simulation in next 50 years;soil survey data and related data as the data source,using the RUSLE model,a calculation method to determine the factors of RUSLE value,analyzes the spatial distribution and dynamic change of soil erosion in Chaohu Watershed,and the analysis of the land use / Cover Change and soil erosion,draw the following conclusions:(1)the paddy field,forest land and urban and industrial land is the main land types in Chaohu Watershed in recent 20 years.Grassland and unused land,the proportion is very small,the proportion is less than 1% of the total area,followed by dry land,only about 2%.The Chaohu Watershed is the largest area of paddy field,followed by woodland,urban and industrial land and waters.And the area of urban and industrial and mining land increased year by year.Chaohu Watershed is in the stage of urban expansion,the continuous improvement of the level of urbanization,the urban and industrial and mining increased,reduce the area of paddy field;and waters of irregular change,water area have increased 103.49 km2 of the is mainly caused by the development of the construction of the reservoir and aquaculture.(2)In recent 20 years,the land use structure of Chaohu Watershed has changed,which mainly shows that the urban and industrial and mining land has increased by 1044.90 km2.From the point of view,urban and industrial paddy field is built into the main object.The quantity of cultivated land decreased by 1158.29 km2 from 1992 to 2013.On the regional differences,Feixi,Feidong and Hefei City area in the land use pattern change is the most dramatic,is within the watershed land use / cover change in the main reason.(3)Markov model of Chaohu Watershed in the future 50 years of land use pattern of the predicted results show that Chaohu Watershed in the next 50 years,towns and industrial and mining and upland area ratio will be gradually increased;and paddy field area ratio will be further reduced,woodland and water in small amplitude decreasing trend;grassland and non-use in basic stable invariant state.In addition to towns and industrial and mining land development trend of rapid outside,the rest of the land use types of variation in gradually reduce,illustrate this.In the next 50 years,Chaohu Watershed land use / cover spatial pattern will reach a steady state.(4)the Chaohu Watershed in 20 years the average soil erosion modulus decreased significantly.In 1992,soil erosion modulus is 510.70,2006 reduced to 129.79,the rate of decline for 74.59%,2006-2013 soil erosion modulus increased to 149.44,the rate of increase was 15.14%.It is because during urbanization rapid acceleration caused by.Different grades of soil erosion area ratio of significant changes,moderate erosion,strength erosion,extreme erosion and severe erosion by 2.33%,0.09%,0.05%and 1.32% were reduced to 0.68%,0.19%,0.02%and 0.01%.(5)the overall pattern of soil erosion distribution in 1992-2013 in Chaohu Watershed is as follows: along the northeast and southwest of the basin,the distribution of soil erosion is distributed to both sides.Alluvial plain area basically no erosion,erosion area mainly occurred in the low mountain and hilly area.Obviously,the soil erosion of the Chaohu river basin is greatly influenced by the topography.(6)the trend of soil erosion intensity in Chaohu Watershed is obviously decreased.1992-2000 years,there are some areas of soil erosion intensity level rising trend.During the period of 2000-2013,the soil erosion in the watershed of the Chaohu Watershed was greatly improved due to the significant increase of the surface vegetation cover.(7)soil erosion varies in different land use types.Paddy soil erosion area is the largest,accounting for total watershed erosion area 64.42%;followed by the forest and urban and industrial land,total area of 20.98% and 10.36% respectively of the total basin erosion;dry land,waters and the erosion area is lesser,sum total only accounted for watershed erosion 4.24% of the total area.Extremely strong erosion and severe erosion mainly occurred in some parts of Shucheng County,such as dry land and mineral resources.Dry land erosion accounts for a small proportion of total erosion area,but the erosion modulus is as high as 753.