Study On The Spatial Differentiation Law And Influencing Factors Of Earth-Rock Fence In Anning River Basin

Earth-rock fence is a product of the comprehensive effects of natural conditions and human activities.It refers to a vertical spatial partition structure composed of soil,stones,or mixtures of earth and stone,which plays a role in dividing,isolating,and protecting a certain area.The Anning River Basin has complex geological conditions and fragile ecological environment.Due to frequent natural disasters such as landslides and debris flows,it has been designated as a key area for soil erosion and soil erosion control in Sichuan Province.Due to the small amount of arable land in the basin and the fact that it is located in the three major pastoral areas of Sichuan Province,the rough grazing method has brought serious pressure on the utilization of arable land.Therefore,in order to reduce the damage caused by natural disasters and grazing to the cultivated land,and to improve the ability to withstand disasters to some extent,people have built earth-rock fences that combine the functions of fences and water and soil conservation measures using local materials.Due to the comprehensive effects of various factors,the spatial differentiation of earth rock fences in the Anning River Basin is complex,and the influencing factors for spatial distribution are diverse.Therefore,based on high-resolution remote sensing images,this paper obtains the basic data of earth-rock fences in the study area through visual interpretation.Using methods such as nearest neighbor index,statistical analysis,nuclear density analysis,standard deviation ellipse,hot spot analysis,and overlay analysis,it explores the spatial morphology and differentiation laws of earth-rock fences from three aspects:spatial morphological characteristics,spatial distribution characteristics,and spatial distribution differentiation laws;Using geographic weighted regression,principal component analysis,and geographic detectors,this paper quantitatively explores the factors affecting the spatial distribution of earth-rock fences from three aspects:spatial heterogeneity,factor principal components,and factor explanatory power.The main conclusions are as follows:(1)The analysis of spatial morphological characteristics shows that the minimum perimeter of the earth-rock fence is 22.14 m,and the maximum is 1512.24 m.The concentrated distribution range of the perimeter is 111.21～241.05 m;The minimum area of the earth rock fence is 33.40 m~2,and the maximum value is 78001.52 m~2.The area is generally distributed between 694.69 and 2993.90 m~2.The fragmentation index of earth-rock fences in the Anning River Basin is 2.394 pieces/km~2,among which Xide County,Zhaojue County,and Mianning County are significantly higher than other districts and counties and the overall fragmentation index of the basin,indicating that these three districts and counties are more severely divided by earth-rock fences compared to other districts and counties.The fractal dimension of earth-rock fences in the basin is generally in the range of 0.99 to 1.03,indicating that the boundaries of the patches of the earth-rock fences are relatively regular.(2)The exploration of spatial distribution characteristics shows that the distribution density of soil and stone fences in the Anning River Basin is 0.006 km~2/km~2,and the difference in fragmentation and distribution density indicates that compared to Xide County,Mianning County has a larger area of soil and stone fences.The earth rock fences in the drainage basin are distributed in the north-south pattern,with obvious centripetal force and directionality.The soil and stone fence exhibits a clear spatial agglomeration distribution feature,with a significant core-edge distribution,forming several major agglomeration centers located in Mianning County and Xide County respectively;The nuclear density hotspots are mainly located in Mianning County and Xide County,with significant distribution along the river.(3)The study of spatial distribution differentiation found that the proportion of soil and rock fences within a distance of 1500 meters from the river is about 50%,which is consistent with the distribution of nuclear density hotspots.The terrain pattern of the earth-rock fence shows that the area has an elevation of 1768-2749 m,gentle slopes(5-15°)and slopes(15-25°),slopes towards the central eastern slope,southeast slope,south slope,southwest slope,and west slope or sunny slope,terrain undulation of 70～200 m,surface cutting depth of 0-86.45 m,terrain roughness of less than 1.06,elevation variation coefficient of less than 0.019,terrain humidity index of 5.667～10.736,terrain location index of 9.01～7.18,The terrain index of 0.471～0.671 and the middle slope area are areas with a large distribution of soil and rock fences.The climate pattern shows that soil and stone fences are mainly distributed in areas with annual precipitation of9853.800～10448.055 mm and 10935.777～11406.806 mm,and an average annual temperature range of 6.0～13.3℃.The human and social pattern of the distribution of soil and stone fences shows that they are mainly distributed in areas with sparse population density(<190 people/km~2)and areas with low economic conditions.The soil pattern of the distribution of soil and stone fences shows that the proportion of soil and stone fences distributed in dark yellow brown soil,purple soil,and red soil is 85.95%,with a ratio of about 1:2:2;Among the land use types,arable land,forest land,and grassland are the hot spots for the distribution of soil and stone fences,accounting for 99%of the total.Among them,arable land is mainly distributed in dry land,with a distribution ratio of 8:1 for dry land and paddy field.Based on slope differentiation,it can be further concluded that soil and rock fences are mainly distributed in slope farmland,slope forest land,and slope grassland land use types.(4)The research on the influencing factors of earth rock fence shows that the spatial distribution of earth rock fence is mainly affected by soil type,terrain,vegetation,climate and social economy.The terrain factors mainly include elevation,elevation variation coefficient,surface cutting depth,and slope;Climate factors mainly include temperature and precipitation;The main socio-economic factor is GDP.Under the influence of spatial heterogeneity,in the northern part of the study area,the core density of earth rock fences is negatively correlated with slope and surface cutting depth,and positively correlated with the coefficient of variation of elevation and GDP.In the southern part of the study area,the core density of the earth rock fence is positively affected by the slope and surface cutting depth,and negatively affected by the coefficient of variation of elevation and GDP.The results of principal component analysis indicate that most soil and rock fences are distributed in areas with high comprehensive factor scores.The spatial distribution of soil and rock fences is mainly influenced by three comprehensive indicators,the first being terrain and vegetation,the second being climate,and the third being socio-economic factors.The results of geographical detectors show that the top five explanatory factors are soil type,air temperature,GDP,elevation and precipitation,and the top five interactive factors are soil type and precipitation,soil type and temperature,soil type and GDP,soil type and elevation,precipitation and temperature.The research results provide a new understanding of the spatial distribution and influencing factors of earth-rock fences,help to clarify the formation and development mechanism of earth-rock fences,synthesize their spatial differentiation laws and their influencing factors,and provide a theoretical basis for decision-makers to manage and construct earth-rock fences in the river basin.