Research On The Evolution Of Spatiotemporal Pattern Of Water Use Efficiency And Its Cause In Guangdong Province

Water resources are fundamental natural resource,strategic economic resource and important elements of ecological environment.Water resources shortage and water pollution become global challenge due to human’s unreasonable exploitation.With the most population,China is one of the severe water-shortage countries in terms of per capita water resources and more than half of provinces face water resources shortage in China.As one of the most economically developed provinces in China,Guangdong province has ranked the first in terms of total GDP for 32 years,while it also ranks the first in terms of discharge of wastewater along with the rapid socioeconomic development.Besides,the per capita water resource of Guangdong is lower than the national level,the uneven spatiotemporal distribution of water resources within Guangdong province and the influence of downstream salt tides in Pearl River Delta make Guangdong province facing the pressure of water supply safety due to high quality economic and social development,constrained total water use and water environment protection.Water use efficiency（WUE）reflects the effective degree of water utilization.Improving WUE is of great significance for alleviating regional water resources shortage and water pollution.The important premise of achieving sustainable economic and social development is to scientifically evaluate the status of WUE and systematically analyze the spatiotemporal pattern of WUE and its causes.For this purpose,based on the long time series of economic,social and water use statistics in Guangdong province from 2006 to 2019,this thesis initially improved the current Super-slack based model（Super-SBM）and calculated WUE of the whole province using the improved SuperSBM model and revealed the evolution of spatiotemporal pattern of WUE via the spatial autocorrelation method and Theil index.Then Geographically and Temporally Weighted Regression（GTWR）model and Spatial Markov Chain were employed to identify the main influencing factors of the spatiotemporal evolution pattern of WUE.The driving mechanism of the spatiotemporal pattern of WUE were discussed from the perspectives of spatial heterogeneity and spillover,and several corresponding countermeasures and suggestions on the spatial equilibrium regulation of WUE were put forward.The main conclusions are as follows:（1）The improved Super-SBM model can effectively prevent the underestimation of WUE.The value of standard deviation of WUE is larger when the output indicator involves social benefit,economic output and undesirable output of environmental pollution,indicating that it has good performance at the degree of discrimination.（2）The spatial pattern of Guangdong province’s WUE basically presents radial distribution,with high WUE located in Pearl River Delta（PRD）.The global Moran’s I and local Moran’s I show that WUE in whole province has significant positive spatial autocorrelation,among which the cluster of High-High locates in PRD,and the cluster of Low-Low locates in Northern Guangdong（NG）and Eastern Guangdong（EG）.Meanwhile,the degree of spatial cluster initially strengthens and then weakens.With regard to the spatial difference of WUE,Theil index shows that the spatial difference appears the tendency of initially narrowing and then intensifying,among which the contribution of internal regional difference to total difference reaches 60% during 2009～2016.In addition,the order of spatial difference between sub-regions shows that the PRD is the greatest,followed by WG and then EG,the NG ranks the last,among which the PRD makes the greatest contribution to internal regional difference.（3）Per capita GDP,per capita water use,proportion of water use by secondary and tertiary industries,proportion of R＆D expenditure and foreign direct investment（FDI）are identified as the major influencing factors.In terms of spatial heterogeneity,1)per capita GDP exhibits inhibiting effect in improving WUE in NG;2)per capita water use restrains the improvement of WUE,especially for the PRD;3)proportion of water use by secondary industry makes restrained effect in WG and EG;4)proportion of water use by tertiary industry facilitates the improvement of WUE,and shows a strengthened tendency from east to west;5)proportion of R＆D expenditure makes the greatest positive influence on the improvement of WUE in NG,while it has the inhibiting effect in that in EG;6)the FDI promotes the improvement of WUE,and exhibits a strengthened tendency from west to east.In terms of spatial spillover,there exists in spatial spillover effect of WUE between cities in Guangdong province,indicating that cities with higher WUE make positive spillover effect on neighboring cities,and conversely make negative spillover effect,which leads to the agglomeration of high and low WUE,and finally causes the spatial difference of WUE in whole province.（4）The corresponding countermeasures and suggestions oriented to spatial equilibrium regulation of WUE are put forwards,mainly including making efforts to reduce per capita water consumption in PRD,optimizing water consumption structure of steel and petrochemical in main production area along coast,improving the quality of investment of R＆D and enhancement of FDI in NG,WG and EG.