Enviromental Risk Assessment Of Metal Tailing Ponds In Daye Based On RS And GIS

Tailing pond is a indispensable facility of mining enterprise, which plays significant function in environment and resourse protection. Nevertheless, tailing pond is mining enterprise’s biggest hazard identification. Many mine accidents are prone to happening at this place. Kinds of geological disasters that tailing pond courses, like debris flow, landslide, soil and water pollution, etc. not only affect mine’s normal operation, but also seriously threaten the surrounding residents’ and environment’s safety. Consequently, it is very important to have research on tailing pond’s environmental risk. Also making environmental risk assessment of tailing pond is necessary, which plays an vital role in reducing the environment risk of tailings operation, ensuring the safety of residents and ecological environment around the tailing pond.Environmental risk assessment is a essential content and a new research direction of building project’s environmental impact assessment. Based on environmental risk assessment fundamentals, environmental risk value is the product of risk occurring probability and risk hazard. This paper used the risk value to determine tailing pond’s risk level. Combining with the natural and geological environment of the research area, taking WorldView-2remote sensing image, basic geographic data, this paper used synergy methods of remote sensing monitoring and ground survey to proceed space-ground monitoring to tailing ponds. With GIS technologies, the paper acquired tailing ponds’monitoring information, containing scales, types, covering area, spatial distribution, etc., then analyzed the possible environmental problems that tailing ponds may produce.Analytic hierarchy process (AHP) is a multi-objective decision-making method that decomposes decision’s related elements into objectives, criterions, programs, etc. to proceed with further qualitative and quantitative analysis. It is widely used in recent years. Based on RS and GIS, the research built a hierarchical structural model of tailing pond’s environmental risk assessment with AHP. It divided environmental risk into perniciousness and probability(objective layer), then divided perniciousness into toxicity, potential, risk suffers and divided probability into itself conditions, natural elements, else factors(criterion layer), finally divided these criterion factors into21measurable index factors, containing minerals, volume, dam height, drainage area, etc.. The assessment model contained4layers and21index factors. The paper constructed the weight discriminant matrix with AHP and expert scoring method, then calculated each index’s weight and quantified them.With the environmental risk assessment structural model and RS monitoring, GIS technologies, ground survey, the paper took Tongshankou copper tailing pond in Daye as a risk assessment case study. This provides beneficial reference for regional other tailing ponds and tailing ponds’daily emergency maintenance and management.The paper obtains the conclusions below:(1) The thesis extracted the research area’s nonferrous metal tailing ponds, analyzed the tailing ponds’features and potential environmental risk problems. It extracted360pond patterns from WorldView-2remote sensing image, counted their covering area is6.15square kilometer. There are253small tailing ponds (covering area is1.07square kilometers),100middle tailing ponds (covering area is2.57square kilometers) and7large tailing ponds (covering area is2.51square kilometers). Large tailing ponds’area occupies41percent of the total. They bring about serious environmental risk because of their big scale and volume. Therefore, large tailing ponds are the focus of the tailings’environmental monitoring and prevention. It could be concluded after comprehensive analysis that the research area’s tailing ponds produce serious potential environmental hazards and risks, mainly including sudden geological disasters like debris flow, landslide, etc. and chronic environmental disruptions like land occupation, dust pollution, Water and soil’s heavy metal pollution, etc..(2) The thesis built a hierarchical structural index system of tailing pond’s environmental risk assessment (4layers and21index factors). Using AHP, combining with ground measured data and RS monitoring condition, the research built a Comprehensive hierarchical assessment model of tailing pond’s environmental risk based on RS and GIS, which ensured the assessment’s comprehensiveness, integrity and objectivity. With AHP and expert scoring method, the paper calculated each index’s weight and quantified them, which obtained all indexes’quantitative range values.(3) The thesis had a case study on Tongshankou copper tailing pond in Daye with synergy methods of remote sensing monitoring and ground survey. Using remote sensing image as basic data, through GIS technologies, field investigation and meteorological hydrological datas, the study acquired Tongshankou tailing pond’s assessment indexes information, figured out its risk value was0.18, which belonged to general risk level. Nevertheless, Tongshankou tailing pond has huge volume and tall dam, it is close to many risk receptors containing river, resident, farmland and road. It is important to reinforce the pond dam’s stability maintaining and environment safety monitoring in daily especially in flood season. Meanwhile, it is essential to strengthen the risk receptors’protection.Tailing ponds’environmental risk problem is a complicated problem that is affected by various factors.Because I am lack of other areas’professional knowledge and short of energy, the paper has some defects in research techniques, methods and frame, many aspects like theory knowledge and technique methods. Further research should be proceeded in the aspects contained enlarging RS and GIS technologies’ monitoring application range, finding more objective and scientific mathematical method for assessment, and processing macro tailing ponds’ environmental risk assessment from overall perspective. These will improve the research about tailing ponds’environmental risk assessment method and technology and provide guidance for comprehensive and objective tailing ponds’ environmental risk assessment study.