Ecological Environment Vulnerability Dynamic Assessment Based On GIS In Hengyang Basin

Ecological environment is deteriorating, especially the extremely urgent andserious problems faced by developing countries. Hengyang Basin, one of the typicalred soil hilly landform development provinces, is a typical ecological environmentvulnerable area. Because of natural and man-made reasons, the district is serious soilerosion, degradation of natural vegetation, reduce soil quality, and the people livingin poverty, ecological and economic and social problems. Therefore, the evaluationof the eco-vulnerability, promoting ecological construction in the region to achieveeconomic and social sustainable development,is of great significance.Hengyang Basin, on the basis of the analysis overview of the ecologicalenvironment of the study area (the Hengyang Basin) and its ecological environment,Using a combination of administrative units and the raster cell approach, ecologicalenvironment caused by human activities in the environmental vulnerabilityevaluation is divided into the assessment of potential vulnerability indicators and thereality of vulnerability assessment indicators, the reality of fragile ecologicalenvironment refers to the interference impact of human activities. Use "3S"technology to extract climatic factors, soil factors, human activity factors, by theweighted sum of the composite index evaluation model to calculate the value of thefragile ecological environment, in order to make assessment results more intuitive,in accordance with the ecological vulnerability index The division of high to low forthe extremely fragile, fragile strength, moderately fragile, slightly fragile, microdegree of vulnerability of five. And calculate the1990,2000and2005the potentialvulnerability of the three year study area and the reality vulnerability classificationarea statistics, can be found:(1) whether it is a potentially vulnerable or fragile reality, the vast majority of mildfollowing regional strength fragile and above region moderately vulnerable region isvery small, indicating that the Hengyang basin is basically vulnerable only in someareas of medium vulnerability, moderately vulnerable areas in less than10%, duringthe period with some fluctuations, because it is located in the humid subtropicalmonsoon climate zone, four distinct seasons and mild climate, lead to the increase and decrease of the potential vulnerability factor is the seasonal changes inprecipitation, which is the index of drought, the rainfall variability of the rainyperiod.(2)From1990to2000, the reality vulnerability moderate vulnerability reduce,theproportion of human activities on the ecological restoration of the levels ofcontribution is less than the degree of contribution of natural factors on ecologicalrestoration. From2000to2005, the reality vulnerable to moderate vulnerabilityproportion increased, indicating that the impact of human activities on the ecologicaldegradation is greater than the influence of natural factors on the ecologicaldegradation.(3)1990to2000, the main region affected by human activities are Leiyang、Hengdong、Hengshan County、Hengyang County and Qidong County, the area ismainly influenced by natural factors are Changning、Hengnan and Hengyang City.Relative to the level of degradation of2000,2000and2005, apart from QidongCounty, mainly by natural factors, from1990to2000,the other counties and citiesare the same. regions affected by natural and human factors has a certain stability.(4)The nugget/sill is less than25%, space is a strong correlation. The nugget/sillis less than25%, indicating that the ecological vulnerability of space is a strongcorrelation, and from1990to2005, the stability of ecosystem Nugget/sill is greater,the variation caused by samples is more than caused by random factors, the weakerthe spatial correlation, spatial correlation can be found more and more weak.