Application Of Grey Clustering Evaluation In The Water Supply Security Evaluation Of Nanyang City

As the main locality of economic construction,there is a high demand of water supply security for the large population and intensive industry in cities.The water resource in our country is not abundant and the distribution is uneven,which bring certain difficulties to water supply.Now most cities are faced with different levels of water security issues.In this paper,the water supply system in Nanyang is evaluated by grey system theory method,and then the water supply safeguard measures based on evaluation results are given.The evaluation index system is constituted with the target layer,criterion layer and index layer.17 indexes are choosed according to the characteristics of water supply system,making the evaluation index system appropriate to the water supply condition in Nanyang;The weight value of indexes is calculated by using grey incidence analysis."Water supply per capita" and "water quality qualified rate" are considered as the characteristic value of water supply system,and the relevance between index sequences and characteristic sequences could be translated as weight value.The calculation results is reasonable,important indexes such as "water production capacity per capita","water supply popularizing rate" and "water consumption per capita for daily life" have large weight value;The endpoint triangular whitenization weight function is established based on the evaluation criterion,then the security situation of water supply system is expressed by the distribution of clustering coefficient.The security analysis of 2012 shows that water supply condition of Nanyang is integrally in the degree of "probable security".The source security,water production capacity and manage security are the weak links of water supply system.The main factors that lead to "less security" are "exploitation quantity of groundwater accounted for the proportion of the supplementary amount","water production capacity per capita","water supply popularizing rate","municipal water supply accounted for the proportion of the total water supply" and "spending on water proportion".From what has been discussed above,the main problems of water supply system in Nanyang are excess exploitation of groundwater,insufficient of water supply capacity and imperfect of water supply infrastructure.According to the conclusions,some water supply safeguard measures are given to improve the present situation.The consequence of water supply security evaluation in 2015 and 2020 shows that the security levels of source and water production rise as the south-to-north water diversion put into use and the water supply security will become more stable.