Effects Of Potential Vegetation Restoration And Terracing Constraction On Soil Erosion In The Yellow River Basin

In recent decades,with a series of ecological management projects implementation in China,such as“Grain for Green”project and Natural Forest Protection project,the ecological environment of the Yellow River basin has been effectively improved,the vegetation coverage has increased significantly.Soil erosion has been effectively controlled.The amount of sediment transported by the Yellow River has been greatly reduced.Vegetation restoration has had a significant impact on soil erosion in the Yellow River basin,but large-scale vegetation restoration has also caused many ecological problems,such as unreasonable vegetation structure causing ecosystem degradation,and excessive vegetation restoration in some areas exceeds the area’s water carrying capacity etc.Therefore,studying the impact of vegetation restoration on soil erosion,and clarifying the potential of vegetation restoration in the Yellow River basin are of great significance for soil erosion control and ecological civilization construction in the Yellow River basin.This study took the Yellow River basin as the research area,collected the data of soil properties,topography,vegetation,land use and other data.We analyzed the temporal and spatial changes of vegetation coverage from 2000 to 2020,and used the“similar habitat”method to predict the potential vegetation restoration of the Yellow River basin.We also analyzed the trend of annual precipitation and average annual temperature changes of the Yellow River basin based on future forecast data.The RUSLE model was used to analyze the changes of soil erosion in the Yellow River basin at different periods,and to quantify the impact of potential vegetation restoration and terraces on soil erosion.Finally,we explored the changes of soil erosion under the"slope arable to terraces"scenario in different periods of the basin,based on the different climate scenarios data from 2021 to 2050.The main conclusions as follows:(1)The ecological environment of the Yellow River basin has been effectively improved from 2000 to 2020.NDVI increased from 0.49 in 2000 to 0.615 in 2020,with an average growth rate of 0.053/10a.The area of vegetation improvement is much larger than the area of vegetation degradation.(2)From 2000 to 2020,soil erosion in the Yellow River basin showed a downward trend.The study area was mainly very slight erosion class,mostly concentrated in the northwest region of the basin and the source area of the Yellow River.The areas with severe soil erosion are concentrated in the gully area,the sandy and coarse sand area of the Loess Plateau and the southeast area of the basin.There were significant differences in soil erosion modulus for different land use types,and the overall manifestations were:cultivated land>unused land>grassland>forest land.The erosion intensity of slope cultivated land is strong erosion class and the erosion amount accounts for more than 60%of the total erosion amount in the basin,which is the main source area of erosion and sediment yield in the Yellow River basin.(3)In the future 30 years,the Yellow River basin will show a trend of warming and humidification,under different climatic scenarios,the annual precipitation and average annual temperature showed a fluctuating upward trend.In the future,there is still a certain space for vegetation recovery in the Yellow River basin.In the southeast of the basin,such as Ziwuling Forest Area,Liupan Mountain and the northern foothills of Qinling Mountains,the vegetation restoration potential index is close to 0,indicating that the zone is close to the maximum recovery potential and the future vegetation restoration space is small.The areas with high vegetation recovery potential are mainly located along the Yellow River in the northwestern part of the basin.The marginal areas of Kubuqi Desert and Mu Us Sandy Land are affected by human vegetation restoration,and there is a certain potential of vegetation restoration.The vegetation restoration potential of Loess Plateau in northern Shaanxi is limited.(4)Vegetation restoration and terracing can effectively reduce soil erosion.Terracing measures reduced the average annual soil erosion modulus by 9.55%,and the area of soil erosion decreased by 12,800 km~2.Under the vegetation restoration potential,the average annual soil erosion modulus decreased from 2169 t/km~2/a to 1769 t/km~2/a under the vegetation restoration potential,a decrease of 18.44%,and the area of soil erosion decreased by 63,100 km~2.In the future,under different climate scenarios and"slope arable land to terraced"scenarios,although the rainfall erosivity gradually increased,the area of strong erosion class and severe erosion class decreased,indicating that the construction of terraces could effectively reduce soil erosion in sloped cultivated land.