Comprehensive Analysis On The Quality Of Drinking Water In Zhejiang Province By Spatial Analysis

Objective Drinking water safety is always the hotspot the government and people concerned. The water quality will directly influence the people’s health. According to statistics,80%of the epidemiological data has spatial attributes, also drinking water data has obvious geographical characteristics of spatial distribution. Spatial analysis can use the spatial information that traditional statistical methods not used yet.It provides researchers with a new, reliable, scientific and reasonable spatial information processing method. The results of this thesis, show the quality of drinking water situation in Zhejiang Province, but also provide a theoretical basis for the government to develop drinking water policy.Material and methods The drinking water quality monitoring data of Zhejiang Province in2010was collected. And the electronic map was obtained from the electronic map of1:400million Chinese county boundaries in National Fundamental Geographic Information Network database. The finished water and terminal tap water samples of all waterworks with hygiene license in Zhejiang Province formed the monitoring drinking water samples. The finished water was monitored once in dry or flood season. The terminal tap water was monitored as follows:one terminal tap water sampling was set with population of per20,000in water supply area; each sampling was monitored once quarterly."Drinking water health standards (GB5749-2006) and drinking water standard test methods"(GB/T5750-2006) carried out the inspection and evaluation. The drinking water quality monitoring data summary, the qualification rate of computing and data conversion completed in EXCEL2003. Spatial analysis completed in the ARCGIS10.0and GS+9.0.Result1. The drinking water quality of area maps The finished water and terminal tap water qualification rate area maps produced under the monitoring data of2010drinking water quality in Zhejiang Province and Zhejiang County-border electronic map.2. Three-dimensional trend analysis The finished water and terminal tap water qualification rate exist trends in the East-West and North-South direction. The trend of higher terminal tap water qualification rate in Central Zhejiang than in other regions in the North-South direction is more pronounced.3. The fitting results of semivariogram function Finished water:nugget variance is0.0095, sill variance is0.2040,the ratio of nugget variance to sill variance is0.047, the maximum range of spatial autocorrelation is0.297,and goodness of fit is0.616, model fitting is good. Terminal tap water:nugget variance is0.0799, sill variance is0.1608,the ratio of nugget variance to sill variance is0.497, the maximum range of spatial autocorrelation is2.38, and goodness of fit is0.370, model fitting is general.4. Kriging interpolation Finished water:by distribution map, we find that the finished water qualification rate in the southwest of Zhejiang is higher than in the southeast coastal regions. The evaluation indices of prediction error are the following: Mean is0.005024,Mean Standardized is0.01058, Root Mean Square Standardized is0.9694, Root Mean Square is0.4477, Average Standard Error is0.4624. Terminal tap water:we find that the terminal tap water qualification rate in the southwest of Zhejiang and near the Hangzhou Bay area is higher than in the north and southeast coastal regions. The evaluation indices of prediction error are the following:Mean is0.01816,Mean Standardized is0.04646, Root Mean Square Standardized is1.0107, Root Mean Square is0.3187, Average Standard Error is0.3152.The prediction error of cross validation indicates that the spatial distribution map of the finished water and terminal tap water in Zhejiang is a good fitness.5. Analysis of spatial autocorrelation After the global Moran’s I and the global Getis coefficients analysis of finished water and terminal tap water, only the global Moran’s I coefficients of terminal tap water is0.2865and has the statistical significance(P<0.005). Global spatial autocorrelation indicators illustrate that there is cluster with higher qualification rate of terminal tap water in Zhejiang. Through the local Moran’s I and the local Getis coefficient analysis, the clustering performance of finished water and terminal tap water is very similar. Regions with higher water qualification rate cluster locate in the southwest of Zhejiang, near Suichang and Longyou County, while regions with lower rate locate in the southeast coast of Zhejiang, near Ruian City, Pingyang and Cangnan County.Conclusions This thesis shows graphically the geographical distribution of drinking water quality in Zhejiang Province by spatial analysis. It is proved that the clustering performance of finished water and terminal tap water is very similar. Regions with higher water qualification rate cluster locate in the southwest of Zhejiang, near Suichang and Longyou County, while regions with lower rate locate in the southeast coast of Zhejiang, near Ruian City, Pingyang and Cangnan County. So it is beneficial for enacting corresponding policy and taking measures.