The Study On Anti-fouling Performance Of Karst Groundwater In Tai'an City

Water resource, energy, population and ecological environment have become major issues of common concern to all countries, the problem is one of the restraint conditions in the survival and development of human society, arouses more and more attention. Groundwater resource occupies decisive position in our country water resource, but, the karst groundwater exploitation can not be ignored in our country's role, especially in northern china, it has a strategic important role. In recent years, with the rapid development of china's economy and people's living standard continues to improve, the pesticide, fertilizer, sewage and industrial "three wastes" blowoff amount enhance gradually, the antifouling performance and sensitive characteristic of groundwater are day by day remarkable in the northern karst groundwater system, and show the change track effected by multiple factors. Affect by the hydrogeological condition and human activity, the karst groundwater system to some extent changes the initial form, emerge a series of environmental geological problems, such as: overexploitation, unreasonable exploitation, karst collapse and karst water quality degradation, and so on. For the negative evolution of the karst groundwater system, if you do not take measures to control, karst groundwater quality declining, karst water environmental geology problem will intensify. Therefore, studying on anti-fouling performance of karst groundwater system under the influence of hydrological condition and human activities contaminant, dividing the antifouling function grade and carrying out valuation, have importance to our country north karst water resources protection.This paper selects Tai'an city as typical representative of karst area in northern China, based on hydrogeology, geology, china karst, fuzzy mathematics, analytic hierarchy process and other basic theory, using borehole data which obtained from the geological department, systematically study the karst water aquifer dynamic characteristics and chemical evolution law of the karst water system in Tai'an, analyse the relationship of karst water system, water chemistry field, hydrodynamic field and the external environmental condition, establish the evaluation index system and evaluation method of Karst water antifouling evaluation. Eight evaluation factors about shallow groundwater antifouling and four assessment indexs about confined water antifouling have been concluded, using fuzzy theory with the analytic hierarchy process and improved DRASTIC model research methods, study systematically groundwater antifouling function of the karst water system in study area.First, according to the research status of groundwater antifouling valuation, analyse the problems and development trends of groundwater anti-fouling properties, further improve the definition of groundwater anti-fouling, and analyze the factors affecting groundwater anti-fouling and five commonly used methods, establish a karst water anti-fouling evaluation method which based on fuzzy theory with AHP and improved DRASTIC coupling appraises method.Secondly, based on the relevant information of the study area, analyse the natural geographic profiles, geological setting, hydrogeological condition and karst water chemical characteristics, clarify the boundary permeability of study area, karst aquifer rock group division, rich water distribution, karst water recharge, runoff and excretion conditions, karst water quality status, dynamic characteristics and water chemical evolution, etc. The underlying data collection laid the foundation for the selection of evaluation factors and the test of evaluation results.Finally, based on borehole data of the study area, karst groundwater is divided into diving areas and confined water area, choose groundwater depth, topography, water-rich aquifers, impact of the vadose zone media, soil media, vadose zone in clay layer thickness, population density and land use types as the evaluation indicators of karst groundwater diving zone; select the watertight roof depth, impermeable thickness, impermeable rock, aquifer hydraulic conductivity as the evaluation indexes of karst groundwater confined water area; introduce the fuzzy theory into karst water anti-fouling evaluation, make sure the relative membership degree of each evaluation factors on the karst water anti-fouling properties; through the analytic hierarchy process determining the weight of assessment factors; at the same time, in the support of geographic information system (Arcview GIS), overlaying various thematic layers of confined water area and diving area, make karst groundwater anti-fouling properties partition map, bring forward karst environment protection measure, it has laid a solid theoretical basis for the economic sustainable development of taian city and the protection of groundwater resources.