Assessment Of Groundwater Vulnerability In Guangzhou

Groundwater development degree of utilization is low in Guangzhou, until now they have not investigated thoroughly the groundwater capacity, which is avaliable to be utilized, have not got any idea about the water source, nor quality condition of groundwater pollution. Therefore, the study of groundwater vulnerability is till a blank. Here take Guangzhou for example, to access regional groundwater vulnerability, which provides some scientific basis to groundwater management and protection in Guangzhou through differentiating and selecting groundwater vulnerable area.According to the groundwater situation in Guangzhou, the author selected depth to water,net recharge,aquifer media,soil media,topography,aquifer thickness,conductivity of aquifer as the evaluate indexes of groundwater inherent vulnerability; established the DRASTMC evaluation model to evaluate, systematically, the inherent groundwater vulnerability. At the same time, considering the influence by human, it added land utilization and groundwater ability to provide water as an indexes of groundwater special vulnerability, adopts fuzzy method to assess groundwater special vulnerability in Guangzhou.As to the weight, this article uses the fuzzy analytic hierarchy process (FAHP), which can construct fuzzy consistent matrix simply and conveniently. As to the process of indexes, this paper uses ArcGIS9.2 software to vector Guangzhou each indexes, and obtains the grading charts about indexes.When evaluating groundwater inherent vulnerability,this article adopts DRASTMC evaluation model.it weights the grading charts about inherent indexes, obtaining the rank chart of Guangzhou groundwater inherent vulnerability. When evaluating the groundwater special vulnerability in Guangzhou,adopts fuzzy method.Firstly, it calculates the membership functional chart of each index by functional calculus formula, then, by weighting the degree of membership functional charts,obtaining the rank chart of groundwater special vulnerability in Guangzhou. Finally, according to 0.4 and 0.6 weights, this article draws the rank chart of Guangzhou groundwater vulnerability by overlaying the rank chart of Guangzhou groundwater inherent vulnerability and the rank chart of Guangzhou groundwater special vulnerability.Through the study of groundwater vulnerability in Guangzhou, this paper divides the vulnerability of Guangzhou groundwater into five grades: groundwater vulnerability lower, groundwater vulnerability low, groundwater vulnerability medium, groundwater vulnerability high, groundwater vulnerability higher. And analyzes distribution and reason of vulnerability in detail, proposes development countermeasure correspondingly. Through the evaluation of groundwater vulnerability and the fix of vulnerability scope of groundwater, people can adopt practical measures when exploring and utilizing the groundwater in Guangzhou to ensure the sustainable use of groundwater.