| Analysis of the spatial and temporal pattern characteristics and influencing factors of soil hydraulic erosion provides theoretical basis and data support for the prevention and control of soil hydraulic erosion and the comprehensive management of the ecological environment in the region.Taking the middle of the northern slope of Tianshan Mountains as the research area,a method of combining field survey,remote sensing(Remote Sensing,RS),geographic information system(GIS)and mathematical statistics was used,based on the Chinese Soil Loss Equation,CSLE)Calculate each factor in the model to get the soil erosion modulus.Quantitatively analyze the spatio-temporal pattern of soil hydraulic erosion in the study area from 2000 to 2018,analyze the trend of soil hydraulic erosion intensity at different levels in the area,clarify the relationship between soil hydraulic erosion intensity and rainfall,topography,soil,vegetation,and discuss the influence of human factors(land Use,tourism,grazing activities)on soil,vegetation and soil hydraulic erosion intensity.Concluded as follow:(1)From 2000 to 2018,the R value of rainfall erosion factor in the study area generally showed an upward trend,increasing by 43.7MJ·mm/(hm~2·h)every 10 years;the distribution characteristics of rainfall erosion force during the year were obvious,generally concentrated in April-August,it accounted for80.15%of the annual rainfall erosion force;in terms of spatial distribution,the rainfall erosion force gradually decreased from south to north.The range of soil erodibility factor K in the study area was0.0060-0.0716t·hm~2·h/(hm~2·MJ·mm),and the regional average value was 0.0280t·hm~2·h/(hm~2·MJ·mm);the southern middle was low The K factor value was relatively low in the hilly area,while the K factor value in the northern alluvial fan and sloping plain area was generally high.The maximum slope length and slope factor(L,S)in the study area were 31.57,the minimum value was 0,and the average value was 8.38;the high-value areas of L and S factors were mainly distributed in areas with higher altitudes,with an average value of 11.63;the low value The area was mainly distributed in the plain area,with an average value of 3.68.From 2000 to 2018,the B value of the biological measures in the study area was in a fluctuating trend(coefficient of variation of 11.71%),but the arbor woodland tended to be stable(coefficient of variation of 3.06%).Facility land>Other woodland>Rural homestead>Artificial pasture>Shrub woodland>Natural pasture>Arbor woodland.Correlation analysis between the soil erosion modulus measured by the runoff plot and the soil erosion modulus estimated by the CSLE model in the middle of the northern slope of Tianshan Mountains(R~2=0.8734,RMSE=7.7034t/(hm~2·a)),the prediction accuracy was higher.(2)From 2000 to 2018,the intensity of soil hydraulic erosion in the middle of the northern slope of Tianshan Mountains was mainly light and slight erosion,accounting for 32.34-40.87%and 33.36-43.01%of the total area;moderate erosion followed,accounting for 7.37-13.84%of the total area;other areas of erosion intensity account for a relatively small proportion,accounting for 8.61-21.18%of the total area;but in the past 20 years,the areas of light and slight erosion had shown a downward trend,while moderate,strong,The areas with extremely strong and severe erosion were on the rise,and the overall soil erosion intensity was increasing.Spatially,the average annual soil erosion modulus in the past 20 years was Urumqi>Changji>Fukang>Hutubi County>Manas County>Shawan County>Shihezi City.(3)Natural and human factors in the middle of the northern slope of Tianshan Mountains comprehensively affected the soil erosion modulus.The rainfall was significantly positively correlated with rainfall erosion force and soil erosion modulus(r=0.9089**,0.6083**;p<0.01).The influence of topography on soil erosion modulus was mainly considered from the aspects of altitude and slope.In general,as the altitude increases,the soil erosion modulus increased.However,when the altitude was between 1800 and 2800 m,the soil erosion modulus decreases slightly,mainly because it was located in the central mountain area and the vegetation coverage was good.When the slope was between 5°-45°,the soil erosion modulus increases with the slope.When the slope was greater than 45°,the soil erosion modulus decreases with increasing slope.When the slope was between 35°-55°,the soil erosion modulus was the largest,indicating that the soil hydraulic erosion in the study area mainly occurs between 35°-55°.Different soil types had different abilities to resist soil erosion,with grass felt soil>grey brown desert soil>brown calcareous soil>chestnut soil>cold calcium soil>black felt soil>grey desert soil>black calcareous soil>grey brown soil>New fill.Vegetation can protect the soil.Vegetation coverage was inversely proportional to soil erosion modulus.When the vegetation coverage was less than 15%,the soil erosion modulus was the largest;when the vegetation coverage was greater than 75%,the soil erosion modulus was smaller.The average annual soil erosion modulus in the past 20 years had been different due to different land use types,showing other grasslands>natural pastures>shrub land>mining land>land for scenic facilities>other woodland>inland tidal flat>rural homestead>artificial pasture land>dry land>arbor woodland>irrigated land.Increased tourism or grazing intensity had significant positive or negative effects on vegetation,soil and soil hydraulic erosion.With the increase of tourism and grazing intensity,vegetation characteristics(coverage,height,aboveground biomass),soil volume water content,organic matter content decrease,soil bulk density increases,soil erodibility factor K value and biological measure factor B value were both Increase,the soil erosion modulus increases accordingly.With the increase of total tourism income and total output value of animal husbandry,the soil erosion modulus was increasing.The occurrence of soil erosion in the middle of the northern slope of Tianshan Mountains was mainly affected by rainfall factors.Among the driving forces of each factor,rainfall(0.4888)>soil type(0.1657)>elevation(0.1520)>slope(0.1080)>vegetation coverage(0.1004)>land use type(0.0395). |
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