Spatial-temporal pattern evolution of wastewater discharge in Yangtze River Economic Zone from 2002 to 2015

This study uses Exploratory Spatial Data Analysis (ESDA) method and Logarithmic Mean Divisia Index (LMDI) model to analyze and discuss the Spatial-temporal pattern as well as the dominant driving factors of wastewater discharge in Yangtze River Economic Zone from 2002 to 2015. The paper indicates that: (1) In terms of the spatial-temporal pattern, the amount of wastewater discharge in Yangtze River Economic Zone shows an increase trend from 2002 to 2005, and then put up a decline trend between 2005 and 2015. Referring to the spatial characteristics, firstly, the amount of wastewater discharge increases from upstream to downstream. There are few high discharge cities whereas more low and middle discharge cities. Secondly, a certain amount of wastewater discharge transfers from the downstream to the midstream and upstream, and the wastewater discharge in mountainous area is lower than other regions. (2) In terms of the change of spatial relationship among cities in the research area, the wastewater discharge shows a significant spatial agglomeration. High discharge cities are concentrated in the Yangtze river delta and low discharge cities are distributed in underdeveloped areas in the western part of China, especially the tourism-oriented cities. (3) In terms of the driving factors, the technical improvement effect did a negative contribution and controlled the amount of wastewater discharge, whereas the industrial structure effect did a positive or a negative contribution depend on the policy and market. The economy development effect, which was one of the dominant factors, did a positive contribution to the amount of wastewater discharge. Moreover, the population scale effect did a positive contribution to the wastewater discharge, but the impact is not significant.