Climate Change In Songliao River Basin And Response Of Potential Soil Erosion To Climate Change In Typical County In Recent 35 Years

This thesis will base on the daily rainfall,daily average temperature data of 129 meteorological stations and daily erosive precipitation data of 303 meteorological stations(daily precipitation is more than 12mm)in Songliao basin from 1980 to 2014,the temporal and spatial characteristics of climate change in recent 35 years in Songliao basin were analyzed by using MATLAB,Arc GIS,Excel and Mann-Kendall test,spatial interpolation,correlation analysis and other methods.On this basis,binxian county,a typical county in Songliao basin,was selected.According to the high score No.1(2m panchromatic,8m multispectral)remote sensing images in 2014,DEM data with spatial resolution of 10 m,soil map and digital map of the county The main conclusions are as follows:1.Spatial-temporal characteristics of climate change in Songliao basin in recent 35 years.(1)The average precipitation of Songliao basin from 1980 to 2014 was 547.77 mm,the year of the highest precipitation was 2012,692.14 mm,and the year of the lowest precipitation was 1999,434.06 mm.In recent 35 years precipitation,1998 is the first abrupt change point,in that year,precipitation cumulative anomaly value is the largest,318.83 mm,2009 is the second abrupt change point,precipitation cumulative anomaly value is the smallest,is-266.64 mm.The general trend of precipitation is decreasing from southeast to northwest,Dandong area and near the most precipitation,annual precipitation of 900 mm,Hulun Buir league area and near the least precipitation,annual precipitation of 300mm-500 mm.The spatial distribution of precipitation in each season is the same as that of annual precipitation.(2)The mean temperature of Songliao basin from 1980 to 2014 was 5.11?,the year with the highest mean temperature was 2007,6.38?,and the year with the lowest mean temperature was 1980,3.81?.1988 was the abrupt change point of temperature.The general trend of temperature change in Songliao basin is decreasing from south to north.The average annual temperature in Dalian and its vicinity is the highest,at about 10?,the average annual temperature in hulun buir league and its vicinity is the lowest,below 0?.(3)The average rainfall erosivity R value from 1980 to 2014 in Songliao basin was 2003.79 MJ·mm/hm2·h·a,the minimum rainfall erosivity year was 1999,1393.58 MJ·mm/hm2·h·a,and the minimum rainfall erosivity year was 1994,3419.08 MJ·mm/hm2·h·a.The area with the largest rainfall erosivity is mainly concentrated in the south of Songliao basin,Dandong city has the largest rainfall erosivity and the smallest rainfall erosivity is concentrated in hulunbuir league area.The correlation between annual rainfall erosivity and annual precipitation was analyzed.The calculated correlation was 0.849,and the correlation coefficient was close to 1.The results showed that the correlation between annual rainfall erosivity and annual precipitation was high in Songliao basin.2.Response of potential soil erosion to climate change in typical counties of Songliao basin in recent 35 years.(1)In binxian county,dry land and woodland are the major land use areas,followed by residential areas and industrial and mining land,water and water conservancy facilities.Along the northern border of binxian county,rivers and waters are mainly distributed,along the southern and eastern border of binxian county,there are mainly large forest land,and other areas are mainly distributed in dry land and residential land.Paddy fields are mainly distributed near rivers in the north and large areas of water in the middle.(2)In recent 35 years,the average annual rainfall erosivity in binxian county was 1646.44 MJ·mm/hm2·h·a,the maximum value was 1739.83MJ·mm/hm2·h·a,the minimum value was 1585.32 MJ·mm/hm2·h·a,and the standard deviation was 27.71.the overall change trend was decreasing from south to north.(3)With the change of rainfall,the potential soil erosion also changes.Through the analysis of the annual erosion in 1986,1993,2000,2007 and 2014,it is found that the erosion is the most serious in 1986,with an area of 1026.54 km2 and an erosion modulus of 1062.89 t /(hm2 a);In 2007,the erosion area was slight,the area was 947.95km2,the erosion modulus was 530.5 t /(hm2 a),the difference of erosion area was 78.59km2,and the difference of erosion modulus was 532.39 t /(hm2 a).(4)the rate of change of erosion varies greatly from year to year.The most significant rate of change is the slight erosion from 2000 to 2007.The rate of change is-35.12 %.In all years,the absolute value of the rate of change of erosion intensity in these two years is basically higher than that in other years.The rate of change of slight erosion was large,and the trend was mainly decreasing.The rate of change of strong erosion is small,and the rate of change is about 2 %.