Ecological Risk Assessment Based On Land Use Change In Linjiang City

The ecosystem is an integrated whole consisted by various ecosystems which isconstituted by biological communities and non-organism natural factors, and it is the supplierof material and energy and the carrier of survival and development for all the life organisms inthe region. Since the industrial revolution was carried out in19th century and with thedevelopment of sustainable economic in the region, the human activity was also triggered aseries of ecological and environmental issues, such as extinction of species, land degradationand global warming, which result in the decline of environmental quality. And this seriouslyaffected the quality of human life, and constrained the social and economic sustainabledevelopment.So far, the research and application of environmental risk assessment is mostlyconcentrated in the human health risk assessment, but for the long-lasting, relatively slowchanges in natural ecosystem caused by human activities and various natural factors it is lackof vigilance.On the basis of summarizing existing ecological risk assessment, this paper see the landuse as the risk source which cause the change of ecological risk, and carry out the study ofecological risk assessment in the context of land use change, and form a relatively complete,systematically theory and methodology for ecological risk assessment under the land usechange. Generally speaking, this paper conducted a study of following aspects:1. Using three images of Landsat TM in1990and2000and2010as the data source,using ENVI image processing software, combining the unsupervised classification of remotesensing and artificial visual interpretation, extracted the land use information in Linjiang in1990,2000and2010.And then take advantage of the ArcGIS data analysis software, analyzedthe spatial and temporal evolution of land use type from1990to2000and from2000to2010.And combining the demographic and economic statistics, applied the logistic regressionmodel to do the analysis of the various driving factors. And the results showed that, the mainfactors affecting the land use change in Linjiang area are average annual temperature, annualprecipitation, the distance from the nearest residential area, the distance from the nearest riverand the distance from the nearest road.2. Based on land use change, combining the related theories about risk assessment,selected the indicators of risk evaluation corresponding to the degree of land use. Andestablish the ecological risk assessment index system on the base of land use change.3. Dealt with the various indicators under the ArcGIS software, and resampled everyindicator into raster data of30m multiple30m, then used an integrated assessment model atthe gird cell level to establish the integrated ecological risk index. At the same time, used thespatial analysis methods to do the space quantization for ecological risk index, generate themap of the ecological risk degree in Linjiang, and analyzed the spatial distributioncharacteristic and form mechanism of the ecological risk in the study area. The analysis resultshowed that although the Linjiang city is on the edge of the natural reserve zone, the integrated risk index is not so high, but due to the deforestation imbalance, the structure offorest quality has severely degraded. As the road cutting in the space and the expansion of thebuilt-up area and encroachment of industrial and mining areas, the fragmentationphenomenon of the original natural landscape is growing on serious. The result of ecologicalrisk assessment showed that, the ecological risk in Linjing city has a very significantdifference, the densely populated cities and towns like the Sengong Street have a higherecological risk index.4. Used the spatial overlay analysis in the ARCGIS software to overlay the ecologicalrisk distribution map of three periods in1990,2000and2010, and get the temporal change ofecological risk in Linjiang area. It can be seen from the result that, after ten years, because ofthe development of urbanization and the increase of land use degree, the ecological risk indexin Linjiang area has a tend to getting large. Combining the map of land use change in Linjiang,make the correlation analysis of the ecological risk change and the land use change, and itrevealed that, land use change has a positive impact to the ecological risk change at someextent, and in the region with a large land use change, the changes in its ecological risk valueis also greater.