Evaluation Of Ecological Sensitivity And Value Of Soil And Water Conservation In Typical Managed Small Watershed Of Loess Plateau

Identifying the current natural conditions and the anti-interference ability of the ecosystem under the background of human interference is an important part of the country’s major strategy for the construction of ecological civilization.In order to protect the ecological environment of the Loess Plateau and realize the harmonious coexistence between man and nature,this study uses five typical small watersheds(Nihegou,Quanjiagou,Wangdonggou,,Zaozigou and Zhifanggou)as the research area.After nearly20 years of comprehensive management from the Sixth Five-Year Plan to the Ninth Five-Year Plan,the ecological sensitivity status and the temporal and spatial evolution characteristics of soil and water conservation value will be discussed and studied.Based on the research and construction of the ecological sensitivity evaluation index system of the study area,combining the characteristics of the natural environment of typical small watersheds and the interference of human activities,this study selects five factors including slope,undulation,soil erosion status,land use type and vegetation coverage status.Sensitivity factors,using remote sensing and geographic information system technology,introducing the entropy method to determine the weights and constructing a comprehensive evaluation model for the ecological sensitivity of typical small watersheds.At the same time,the transfer matrix is used to evaluate 5 typical small watersheds in the 20 years of governance restoration period(1998-2018).The ecological sensitivity of the basin and its temporal and spatial changes are analyzed.When estimating the value of soil and water conservation,the soil conservation value and water conservation value were selected as representative indicators,and the total value of water and soil conservation in 5 typical small watersheds was determined.Finally,the paper analyzed the ecological sensitivity of typical small watersheds and the spatial distribution of soil and water conservation values.Researched the inter-annual changes and the correlation between the two.the result shows:(1)From the perspective of the time change of comprehensive ecological sensitivity,the comprehensive ecological sensitivity of the five typical small watersheds has decreased significantly in the past 20 years.The average sensitivity of Nihegou,Quanjiagou,Wangdonggou,Zaozigou and Zhifanggou decreased by 0.34(3.26 → 2.92),1.95(6.38 →4.43),1.81(4.59 → 2.78),0.51(3.08 → 2.57),respectively),1.89(5.99 → 4.10),the ecosystem’s anti-interference ability to the outside world is significantly enhanced.From the perspective of spatial changes,the overall sensitivity level of the five typical small watersheds has decreased overall in the past 20 years.The areas of Nihegou,Quanjiagou,Wangdonggou,Zaozigou and Zhifanggou basins with constant sensitivity levels accounted for 60.72%,7.46%,5.31%,6.19%,and 25.66%,respectively,with the grades from high to low areas The area accounts for 25.30%,91.48%,93.79%,93.02%,64.61%,and the area from low to high area accounts for 13.98%,1.06%,0.90%,0.79%,and 9.74%,respectively.This shows that the ecological environment of the typical small watershed in the Loess Plateau has been significantly improved in the 20 years after comprehensive management,and the ecological management effect has been significant.(2)From the perspective of the total value of water and soil conservation,the value of water and soil conservation in 5 typical small watersheds has increased significantly in the past 20 years.Nihegou,Quanjiagou,Wangdonggou,Zaozigou and Zhifanggou have increased rates of total soil and water conservation values of 76.10%,26.74%,58.13%,136.51%,and 158.73%,respectively.Among them,the growth rates of soil conservation value were 74.18%,12.10%,67.08%,68.45%,and 138.65%;the growth rates of water conservation value were 78.20%,90.04%,44.74%,232.19%,and 233.92%.(3)Through the analysis of the spatial correlation between ecological sensitivity and soil and water conservation value,the correlation between the two has been greatly weakened.The correlation coefficient of the Nihegou watershed decreased from 0.54 to0.42 in 2018,but still showed a medium-strength correlation;the correlation coefficient of the Quanjiagou watershed decreased from 0.30 to 0.07 in 2018,that is,the correlation coefficient changed from weak to almost irrelevant;The correlation coefficient of Wangdonggou watershed decreased from 0.86 to 0.27 in 2018,that is,the correlation coefficient changed from strong correlation to weak correlation;the correlation coefficient of Zaozigou watershed decreased from 0.72 to 0.20 in 2018,that is,the correlation coefficient changed from strong correlation to weak correlation;Zhifanggou The watershed correlation coefficient decreased from 0.73 to-0.01 in 2018,that is,it turned from a weak correlation to almost no correlation.In general,after the implementation of ecological protection measures in a typical small watershed on the Loess Plateau during the 20 years from 1998 to 2018,the ecological sensitivity has declined,and the total value of soil and water conservation has increased significantly.There is a correlation between ecological sensitivity and the value of soil and water conservation.The ecological zoning changes are obtained through the comprehensive normalization and superposition of ecological sensitivity and water and soil conservation value,indicating that the typical small watershed of the Loess Plateau has been restored to natural ecology after 20 years of governance,and the overall ecological quality has improved,but the ecology of the Zhifanggou watershed has been damaged.The increase in the area of the treatment area provides a spatial reference for the next stage of ecological management.In summary,based on GIS technology,ecological sensitivity theories and methods,and soil and water conservation value theories and methods,this study has estimated the ecological sensitivity levels of the five typical small watersheds of the Loess Plateau in the study area and the spatial distribution and annual distribution of the total value of soil and water conservation.Global changes have identified key ecological areas for the implementation of relevant ecological measures,which have important practical significance for the ecological research of small watersheds.