The Urban Water Supply Security Evaluation Of Luohe City Based On PCA And Grey Relational Analysis Method

With the speeding up pace of urbanization and industrialization, the total urban water demand is increasing. In some cities, water supply pattern and local water resources don’t match, therefore the contradiction between water supply and demand gradually appears, which will be the main obstacle to the sustainable development of social economy in the future. So it is very important to ensure the safety of urban water supply. At present, city water security study focuses on regional water resources security research, however, the study of water supply security covering the whole process of water supply system from water supply resources to the users is less.In this paper, Grey Theory and mathematical statistics method were adopted to quantitatively evaluate the security of urban water supply. Four subsystems(water supply resources, purification works, water supply network and water users) were employed based on the characteristic of water supply system. Thus, 30 indexes were initially chosen, and then 16 of these indexes were selected based on grey relation clustering analysis method.The Principal Component Analysis(PCA) by Statistical Product and Service Solutions(SPSS)was used to determine the index weight, and the model of grey relational analysis was built to evaluate the urban water supply security level. It was divided intoⅠ~Ⅴlevel from very security to insecurity grade,and the level was determined by the grey comprehensive correlation degree.Taking Luohe as an example, the grey relational analysis model was used to evaluate its water supply security level, and using Analytic Hierarchy Process(AHP)to control. At last, the water supply security level of the city planning in 2020 was also predicted. The main results are as follows:(1) The water supply security of Luohe from 2006 to 2014 was evaluated. The maximum value of the grey comprehensive correlation degree in 2006 was 0.757 corresponding to the basic security grade( Ⅲ level) and the security grades from2007 to 2013 were also in Ⅲ level. In 2014, the maximum value of the grey comprehensive correlation degree was 0.727 corresponding to the Ⅲ level, and thegrey comprehensive correlation degree of Ⅱ level was 0.711. so it was close to the more security grade( Ⅱ level) in 2014. However, the index of per capita water resources was in the insecurity grade(Ⅴlevel), so it was faced with the shortage of water resources.(2) The control comprehensive evaluation based on AHP. The comprehensive evaluation scores gradually decreased from 2006 to 2012, and the water supply security condition were all in the basic security grade(Ⅲ level). Furthermore, the scores in 2013 to 2014 were 2.470 and 2.356, which were all in the more security grade(Ⅱlevel). This result was basically same as the research conclusion of the grey relational analysis model, so the model was effective and feasible.(3) The prediction of water supply security level in 2020. The maximum value of the grey comprehensive correlation degree in 2020 is 0.709 corresponding to the more security grade(Ⅱlevel), and the grey comprehensive correlation degree ofⅠlevel was 0.687. So it’s close to the very security grade(Ⅰlevel). The overall water supply condiction in 2020 is better, but the per capita water resources index is in the less security grade(Ⅳlevel), and the per capita water supply capacity index is in the insecurity grade( Ⅴ level). In addition to the pipeline density of water supply in built-up area index and per capita domestic water consumption index are in Ⅲlevel,the others have reached II and above level.When all of the South-to-North Water Transfer projects are put into operation in2020, the general security of water supply system will be in the more security grade(Ⅱlevel). The main factors that may affect the security of water supply in the future are the lack of per capita water resources and inadequate water supply capacity.Meanwhile, the size of water supply pipe network and urban domestic water-saving capacity is weak, which can provide some advices for urban water supply planning.