| The problem of soil erosion in the Loess Plateau is of great significance for ensuring the safety of our country’s ecological environment,flood control and irrigation,grain red lines,and drinking water sources.In this paper,the revised general soil loss equation RUSLE model is used to comprehensively manage five small watersheds in the Loess Plateau.Based on 2016 remote sensing images,three different resolutions of soil erosion intensity of 15 m,30m,and 90 m are calculated,using multiple fractal theory constructs a multi-fractal spectrum of elevation,land use type,slope and vegetation coverage,and combines three factors of land use type,slope and vegetation coverage to analyze the spatial differentiation characteristics of soil erosion intensity.1.The overall status quo of soil erosion in each small watershed after comprehensive management has been explored.The soil erosion in Nihegou watershed is mainly micro and light erosion,the Quanjiagou watershed is mainly micro and severe erosion,the Wangdonggou watershed is mainly micro erosion,and the Zaozigou watershed is mainly light and slight erosion,Zhifanggou watershed is mainly mild and severe.2.The spatial distribution of different erosion intensities in different watersheds on slope,land use type and vegetation cover.The slight erosion in each watershed is mainly distributed on slopes of <5°,and the slight erosion and above are mainly distributed on slopes of 5°～8° and 8°～15°.As the spatial resolution decreases,the severely eroded area concentrates on 5°～8° slopes;The forests and shrubs in each watershed are mainly slightly eroded,and light and above erosion are mainly distributed in farmland,grassland,and grassland.Hardened ground and bare land;Except for the Quanjiagou watershed,vegetation coverage in the other watersheds is slightly eroded in the interval<0.05,and mild and above erosion is mainly distributed in the interval >0.7 and 0.5～0.7.As the spatial resolution decreases,the erosion in the interval >0.7 and 0.5～0.7 becomes more serious.The erosion of Quanjiagou watershed is mainly concentrated in the interval> 0.7,and is dominated by severe erosion.3.The multi-fractal spectrum of elevation,land use type,slope,and vegetation coverage corresponding to the different resolution DEM of each watershed has a bellshaped characteristic.As the DEM resolution decreases,the extreme values of the multifractal spectrum in the Nihegou,Wangdonggou,Zaozigou,and Zhifanggou watersheds first increase and then decrease.The difference between them first increases and then decreases,the ability to summarize geomorphological information is first weak and then strong,and the complexity of the geomorphology first increases and then decreases;the Quanjiagou watershed first decreases and then increases,which is reflected in the DEM resolution In the case of gradual decrease,the difference between elevations first decreases and then increases,the ability to summarize geomorphological information is first strong and then weak,and the complexity of the geomorphology first decreases and then increases.As the resolution of land use types decreases,the extreme values of the multifractal spectrum in the Nihegou,Wangdonggou,Zaozigou,and Zhifanggou watersheds first increase and then decrease,which shows that the resolution of land use types gradually decreases.The difference between land use types first increases and then decreases.The ability to summarize land use type information is first weak and then strong.The complexity of land use types first increases and then decreases;the Quanjiagou watershed increases,this It shows that when the resolution of land use types gradually decreases,the difference between land use types increases,the ability to summarize land use type information weakens,and the complexity between plots increases.As the slope resolution decreases,the extreme values of the multifractal spectrum in the Wangdonggou and Zaozigou watersheds first increase and then decrease.This shows that when the slope resolution gradually decreases,the difference between landforms first increases After decreasing,the ability to summarize slope information is first weak and then strong.The complexity of the topography increases first and then decreases;the watersheds of Nihegou,Quanjiagou,and Zhifanggou increase,which shows that the slope resolution gradually decreases.Under the circumstance,the difference between landforms increases,the ability to summarize slope information is weakened,and the complexity between landforms increases.As the resolution of vegetation coverage decreases,the extreme values of the multifractal spectrum in the Wangdonggou,Zaozigou,and Zhifanggou watersheds first increase and then decrease.The difference first increases and then decreases,and the ability to summarize vegetation coverage information is first weak and then strong.The complexity of vegetation coverage first increases and then decreases;the Nihegou and Quanjiagou watersheds increase,which shows that the vegetation cover When the resolution gradually decreases,the difference between vegetation coverage increases,the ability to summarize vegetation coverage information decreases,and the complexity of vegetation coverage increases.4.Clarify the main driving force of soil erosion under different resolution DEM conditions.The single-factor detection results of soil erosion intensity show that at 15 m resolution,the main driving forces of soil erosion in each watershed are vegetation cover and land use type;at 30 m resolution,it is vegetation cover and slope,and at 90 m resolution Is the slope.With the decrease of DEM resolution,the effect of land use type on soil erosion is decreasing,the effect of slope is increasing,and the effect of vegetation coverage is basically stable.The two-factor interaction results of soil erosion intensity show that the combined effects of vegetation coverage and slope in each watershed at 15 m,30m,and 90 m resolution have a greater impact on soil erosion intensity.In short,the overall soil erosion of the small watershed under the comprehensive management of the Loess Plateau has improved significantly,with small areas of intense erosion concentrated in local areas(Zhifanggou watershed and Quanjiagou watershed),mainly bare land and 5°～8° slopes.It shows that the comprehensive management of small watersheds in the Loess Plateau has achieved remarkable results in the past 20 years,and soil erosion has been effectively controlled.Therefore,the improvement of the ecological environment and soil and water conservation of the Loess Plateau will continue to focus on soil erosion prevention and control in the future,scientific afforestation,rational use of local land resources,improvement of the ecological environment,control of soil erosion,and further improvement of the ecological environment of the Loess Plateau. |
