| The most serious ecological threat in mountainous and hilly areas is soil erosion caused by irrational land use,which not only causes land degradation and soil nutrient loss,but also leads to frequent floods,river siltation and water pollution and other secondary environmental problems.Soil erosion has seriously restricted the sustainable development of human beings and the practice of ecological civilization.Therefore,it is of great importance to explore the formation mechanism and change process of soil erosion and explore the internal driving force of soil erosion for soil erosion control,efficient utilization and planning of land resources and ecological restoration.In this paper,taking Qianxi County as an example,the land use transfer matrix of 1990 A,2000A,2010 a and 2020 A was established to analyze the dynamic situation of regional land use and reveal the dynamic situation of regional vegetation in 30 years,and the dynamic change characteristics of land use/cover in the mountainous and hilly area of Qianxi county from 1990 to2020 were analyzed.The soil erosion modulus of 1990 a,2000A,2010 A and 2020 A in the study area was quantitatively estimated from rainfall,soil,topography,vegetation and land use types by GIS and In VEST model,and the spatial and temporal distribution of soil erosion was analyzed from different angles.In order to further determine the role of regional soil erosion factors drive,using quantitative analysis of each factor on the soil erosion forces geographic detector size and interactions between factors,and identify areas single factor of soil erosion risk areas,for the regional soil erosion monitoring and prevention to provide data support,provide powerful basis for comprehensive control of small watershed,It provides decision-making support for the coordinated development of social economy and ecological environment.This paper mainly draws the following conclusions:The analysis results of land use/cover change in Qianxi county are as follows: from 1900 to2020,the single ground movement attitude of industrial and mining land is the largest in the region,and this land type has realized from nothing to exist and shows a trend of expansion year by year.The attitude of unused ground movement is negative in all four periods and shows a trend of decrease year by year with large absolute value.By analyzing the land use transfer matrix of the study area,it is found that the area of forest land,arable land,grassland and unused land shrinks,while the area of industrial and mining land,building land and economic forest land expands greatly.Among them,the large area of forestland and grassland is converted into economic forestland,and the increase of industrial and mining land is large,and the amount of transfer-in is far more than the amount of transfer-in.Regional vegetation coverage classification results show that the high vegetation coverage area and percentage decline year by year,moderate and above vegetation coverage area is increasing,but also proves that the regional economic forest land expansion trend year by year,and after the three periods of vegetation coverage overlay analysis: qianxi map vegetation coverage drop area significantly greater than 30 years area.In order to realize the quantitative assessment of regional soil erosion,the In VEST model sediment transport proportion module was introduced,and the results showed that the soil erosion in Qianxi county in 1990 a,2000a,2010 a and 2020 a was 1.25×107t,1.41×107t,1.77×107t and2.00×107t,respectively,showing an increasing trend.Based on the analysis of soil erosion distribution at grid scale,it was found that the erosion intensity and above concentrated in northeast China and some parts of southeast China,and the area and proportion of erosion increased year by year.The spatial distribution pattern of soil erosion intensity was higher in the north and lower in the south,and there was no severe erosion intensity in 1990 and 2000,but the proportion of severe erosion intensity,extreme erosion intensity and intensity grade increased in 2010 and 2020.The distribution of soil erosion in vertical direction has significant topographic characteristics,and the area of 8° ～ 25° slope is the main area of moderate erosion and above,and with the passage of time,all grade soil erosion gradually shifted to the direction of high grade soil erosion intensity.The results show that land use type is the main driving factor of soil erosion,and the other influencing factors from strong to weak are slope,soil type,vegetation coverage,rainfall,population and GDP,which fail to pass the significance test.Biological factor detector showed that land use type and other natural factors except rainfall had significant spatial distribution of soil erosion.The results of risk detector showed that industrial and mining land and unused land,slope 15° ～ 25° and>Soil erosion risk was higher in 35° and low VEGETATION coverage area.The results of interaction among different factors have more explanatory power to soil erosion than that of single factor,and the interaction between land use type and other factors has the strongest explanatory power to soil erosion.Based on the regional distribution and main driving forces of soil erosion,the paper finally proposes measures of soil and water loss control countermeasures:(1)strictly implement partitions,will be a strength of the soil erosion of small watershed division set to focus on prevention and control of regional soil erosion area,for the industrial and mining land use and economic forest area special projects,as soon as possible to restore the mining area of vegetation,scientific planting economic crops;The policy of returning farmland to forest will be strictly implemented in areas with a slope above 25°,economic forest will be planted in areas with a slope below 25°,and farmland improvement will be implemented in areas with a slope below 15°.(2)Improve regional water conservation capacity,accelerate forest and grass restoration,carry out river dredging project,strengthen river and reservoir ecological buffer zone construction project,and improve the overall regional ecological service function.(3)Develop green economy,pay attention to rural ecological protection,change the economic model,and take the road of green and sustainable development.(4)To strengthen the erosion ditch remediation project,to prevent the erosion ditch has been formed to the surrounding soil and water pollution. |
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