Research On The Ecological Security Assessment Of The High-grade Highway In Guizhou Province Base On 3S Techniques

Due to the rapid development of the high-grade highway(HGH) in Guizhou Province,the highway-caused impact on ecological environment especially the ecological security issues it triggered are getting prominent. So it's out of great necessity to carry out investigation on the status quo of the ecological environment along the HGHs all over Guizhou and conduct ecological security assessment (ESA). By means of 3S technologies, we have made in Guizhou Province such a comprehensive and systematic assessment which has rarely been done by both home and abroad. This research is of great significance theoretically and practically for the purpose of promoting harmonious development between Guizhou's HGH construction and environmental protection measures.This paper describes the status quo of Guizhou's HGH development; argues ESA's theoretical foundation as well as 3S technology's application in ESA. Considering the uniqueness of Guizhou's Karst environment and the substantial ecological security problems existed in the research area, we do research from perspectives of natural background, the fragility of ecological environment and impact drawn by human society. Hierarchy analysis method has been adopted to build index system as well as quantitative analysis & assessment on the ecological security conditions of Guizhou's HGH. We use CBERS images as data source to extract the line features representing HGH and consider the buffer areas 2km away from both sides of the HGH as research area. ESA factor extraction technique has been discussed. Taking the remote-sensing (RS) images of CBERS as data source, multiple theme-data and field survey aided, we got RS interpretation of the land use, forest coverage, soil and water erosion and desertification in the research area to yield corresponding result maps. GIS techniques has found its way in making maps for slope, lithology, population density and area division based on the likelihood of geologic disasters. Comprehensive index assessment method has been adopted to calculate HGH's ESA comprehensive indexes which combined with the raster data overlay-analysis yield final ESA result of the HGH. Corresponding measures on ecological security protection has been suggested aiming to solve the substantial ecological problems.The following are our main study areas and conclusions drawn from it:1. Investigation on the status quo of ecological environment along the HGH by means of RS technology has been conducted. Supported by GIS technology, taking the remote-sensing (RS) images of CBERS as data source aided with multiple theme-data and field survey, we have done survey on the status quo of ecological environment along HGHs and its influence area in Guizhou Province. The result demonstrates many ecological problems such as irrational land use, low forest coverage, serious soil & water erosion, high level of desertification and high frequency and variety of geological disasters along the HGH lines.2. Building ESA index system. Hierarchy analysis method has been adopted to build the ESA index system for Guizhou HGH. In accordance with the index selection principles, we choose 8 indexes, they are forest coverage, lithology, slope, erosion intensity, desertification development level, population density as well as land use and the likelihood of geological disasters. 3S technology has been applied to get these indexes and make statistic analysis, establish a database for evaluating ecological security level as well as doing quantitative analysis & assessment on the ecological security conditions of Guizhou's HGH.3. Comprehensive index assessment method has been adopted to conduct comprehensive assessment of ecological security. Referencing the standard of ecological environment quality hierarchy we divide the ecological security level into 5 states as severe warning, moderate warning, pre-warning, relatively safe and safe. The assessment result shows that the overall ecological conditions in the area along Guizhou's HGH are not pleasing. Indexes are low and relatively concentrated ranging from 4.8 to 6.2 which primary represents relatively safe and pre-warning states. Of the 8 HGHs assessed, Zhenshui, Zhensheng, Guihuang, Bijie, Guanxin are in pre-warning state while Guichong, Guixin and Mayu are relatively safe.4. Raster-oriented spatial analysis methods dealing with GIS polygon overlay has been adopted to make ESA. GIS technology enables us to overlay all the factor layers, to do functional operations and finally, output a map illustrating the ESA status quo of Guizhou's HGH. Result shows that maximally 58.17% of the area along the HGH has reached warning level, 33.07% relatively safe, 5.75% moderate warning level, only 3.01% has been considered safe, no severe security threatening.5.We analyze that ESA conducted by comprehensive index assessment method plus GIS spatial analysis method of image overlay may present us an overall and at different scares of picture of the ESA status quo of Guizhou's HGH and it's spatial distribution which are of great significance to carrying out further ecological protection, construction and management of the HGHs.6. Based on the assessment result, we have offered protection measures and countermeasures dealing with ecological security problems that is to pay more attention to the water & soil conservation, desertification management and geological disaster prevention in the areas along HGHs.