Are the Water Quality Improvement Measures of China's South-to-North Water Diversion Project Effective? A Case Study of Xuzhou Section in the East Route.

Ye Pan,Yuan Yuan,Ting Sun,Zhengqiu Fan,Yujing Xie,Yuxin Wang

doi:10.3390/ijerph17176388

Abstract

Xuzhou is the hub city of the east route of China’s South-to-North Water Diversion (SNWD) project and implemented dozens of measures to ensure the water quality security of the water transmission line. In order to detect the effectiveness of water quality improvement measures, the monthly water quality data of five water quality parameters from 2005 to 2015 of six state-controlled monitoring sites in Xuzhou section were selected for analysis. The results showed that the water quality improved from 2.95 in 2005 to 2.74 in 2015, as assessed by the comprehensive water quality identification index (CWQII), and basically reached the Class III standards of China’s Environmental Quality Standard for Surface Water (GB3838-2002) from 2011 to 2015. The trend analysis showed that the decline of ammonia nitrogen (NH3-N) was the most obvious among the five water quality parameters. However, the concentrations of phosphorus (TP) showed significant upward trends at three sites. The positive abrupt change of time series of water quality occurred in 2009–2011. The identification of influencing factors of water quality changes by multivariate statistical methods found that the urbanization factor accompanied by a decrease in agricultural nonpoint source pollution emissions and the enhancement of wastewater treatment capacity, the closure of factories with substandard emissions and precipitation were the major influencing factors of most water quality parameters, which confirmed the effectiveness of measures for water quality improvement in Xuzhou.

Highlights

Interbasin water transfer refers to the construction of water transfer projects across two or more river basins to transfer water resources from the regions with abundant water resources to those in shortage, which is used worldwide to resolve the uneven distribution of water resources among regions [1]
The maximum values of dissolved oxygen (DO) and the minimum values of the other four parameters were defined as the best values, and the minimum values of DO and the maximum values of the other four were defined as the worst values
The water quality in the study area had greatly improved during the monitoring period assessed by comprehensive water quality identification index (CWQII) and basically reached Class III of China’s Environmental Quality Standard for Surface

Summary

Introduction

Interbasin water transfer refers to the construction of water transfer projects across two or more river basins to transfer water resources from the regions with abundant water resources to those in shortage, which is used worldwide to resolve the uneven distribution of water resources among regions [1]. By 2015, more than 160 interbasin water transfer projects had been completed or under construction in about 20 countries and regions, among which the South-to-North Water Diversion (SNWD) project in China is the largest in the world [2]. The SNWD project has a total length of 3833 km trunk canal and is planned to transfer 44.8 billion m3 of water per year when fully completed in. The project has three transfer routes: the east route, the middle route and the west route. The construction of the SNWD project started in late 2002, and the first phase of the east and middle route of the project were completed in 2013 and 2014 [3,4]. Public Health 2020, 17, 6388; doi:10.3390/ijerph17176388 www.mdpi.com/journal/ijerph

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