| The ecological environment in places with substantial soil erosion and ecological fragility is particularly vulnerable to external disturbance,and recovery after damage is exceedingly difficult,which can easily produce serious soil erosion disasters and undermine ecological security.As an ecological barrier connecting north and south,soil erosion in the Yangtze Basin is strongly related to the regional ecological environment and to economic and social development.To ensure sustainability by spatial control of conserving water and soil as well as supervision of artificial soil loss in the Yangtze River Basin,it is critical to delineate soil or water conservation ecological vulnerability zones and evaluate soil along with water conservation ecological vulnerability in usual Yangtze River Basin counties.The study occurred in Jinsha County and Qixingguan District.Guidelines for evaluation and study of conserving soil and water ecological instability zones in the basin of the Yangtze were set and their reach defined in line with applicable laws and rules such as the laws on Soil and Water Conservation and the Yangtze River Safety Law on managing the needs of restricting mining and building activities.It happened in Jinsha County and Qixingguan District.Guidelines for assessing and studying the preservation of watersheds and ecological instability zones in the watershed of the Yangtze were developed and implemented according with applicable law,like laws on saving water and soil and the Yangtze River Safety Law on managing needs of restricting mining construction activities.Based on Jinsha County,we built a preserve water and soil ecological vulnerabilities method model and a logistic regression model in quantifying risks of soil and water conservation ecological vulnerability in Qixingguan District,and we analyzed and compared each model to serve as base for upcoming studies.Here are the primary conclusions:(1)The ecological fragile zone of soil and water conservation changes as something where capacity of ecosystems endure outside cause and keep theirs stability is weak,and the risk of soil loss and rock desertification exists after destruction by humans,and it is difficult to repair,given the traits of the Yangtze River basin and added rules and laws.Through the combination of qualitative and quantitative,the research rules and delineation indexes of soil and water conservation ecological fragile zone are established.The zoning results indicate vicinity of soil and water conservation ecological fragile zone in Jinsha County is 276.36km~2,which is 10.97%of Jinsha County’s territory,and the soil-water conservation ecological fragile zone mainly lies in Pingba Township,Anluo Township,Shiba Township,Taiping Township,plus other townships;the area of soil and water conservation ecological fragile zone in Qixingguan District is 450.44km~2,accounting for Tiankan Township,Qingshui Shop Township,Yangjiawan Township,Puyi Township,and different townships are most sensitive regions of saving water and soil in Qixingguan District.(2)Jinsha County and Qixingguan District have more ecologically fragile areas for soil and water conservation in the north than in the south,and they are scattered but not concentrated.All the communities are roughly dispersed,however there’s considerable variances between them.From the topographic distribution,there’s an array of distribution on mountaintops with dangerous slopes and steep terrain;from the facts near waterways,there is an area of soil and water conservation ecologically fragile areas near water systems,and it is a correlation between soil and water conservation ecologically fragile areas and drinking systems.Therefore,the influence factors are selected from topographic conditions,vegetation,land use types,landscape patterns and socio-economic aspects to quantify the ecological vulnerability evaluation of soil and water conservation.Each influence was split into a variety(or intervals)based on location and traits of soil and water conservation ecological vulnerability areas of Jinsha County and Qixingguan District,and the spread of soil and water conservation ecological vulnerability areas in the subsets(or intervals)investigated.It is found that forested grassland,with elevation range of 800-1800m,topographic relief below 60m,slope of 10-40°,vegetation cover between less than 15%and 25-35%,water content of 0.08-0.16,average annual temperature of 15-17℃,and landscape fragmentation in the range of 0-60 are potential ecologically fragile areas for soil and water conservation.(3)Given findings of a sensitivity test of effects in water and soil conservation ecological vulnerability area,15 evaluation factors selected as gauges of soil and water conservation ecological vulnerability quantification using level of correlation between those factors to find the factors’feasibility.Jinsha County devised an evaluation model of ecological vulnerability of soil and water conservation based on weighted information quantity technique and logistic regression approach.From both models,ecological vulnerability of soil and water conservation in Qixingguan District predicted.Validity and accuracy tests revealed both models’reasonableness levels met those requirements,and accuracy at the weighted information quantity approach was greater over that of the log-regression method.The Roc curve and Re value tests showed weighted information quantity approach had better reliability and higher AUC and Re values than the logistic model analysis method.paired rationality and accuracy tests showed risk assessment way of ecological vulnerability of conserving water and soil with weighted information quantity method performed better. |
