Water Environmental Capacity Calculation Based on Control of Contamination Zone for Water Environment Functional Zones in Jiangsu Section of Yangtze River, China

Qiuxia Ma,Yong Pang,Ronghua Mu

doi:10.3390/w13050587

Abstract

In recent years, due to unsustainable production methods and the demands of daily life, the water quality of the Yangtze River has deteriorated. In response to Yangtze River protection policy, and to protect and restore the ecological environment of the river, a two-dimensional model of the Jiangsu section was established to study the water environmental capacity (WEC) of 90 water environment functional zones. The WEC of the river in each city was calculated based on the results of the water environment functional zones. The results indicated that the total WECs of the study area for chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and total phosphorus (TP) were 251,198 t/year, 24,751 t/year, and 3251 t/year, respectively. Among the eight cities studied, Nanjing accounted for the largest proportion (25%) of pollutants discharged into the Yangtze River; Suzhou (11%) and Zhenjiang (12%) followed, and Wuxi contributed the least (0.4%). The results may help the government to control the discharge of pollutants by enterprises and sewage treatment plants, which would improve the water environment and effectively maintain the water ecological function. This research on the WEC of the Yangtze River may serve as a basis for pollution control and water quality management, and exemplifies WEC calculations of the world’s largest rivers.

Highlights

Jiangsu Province, a Chinese province currently undergoing rapid economic development, is faced with serious problems with regard to its water environment [1,2,3]
Nanjing directly discharged the most pollution into the Yangtze River; the amounts of chemical oxygen demand (COD), NH3 -N, and total phosphorus (TP)
The percentage bias (PBIAS) and Nash–Sutcliffe efficiency coefficient (NSE) of the simulated water level were calculated according to the measured water level data of Nanjing Station (NJ) and Zhenjiang Station (ZJ)

Summary

Introduction

Jiangsu Province, a Chinese province currently undergoing rapid economic development, is faced with serious problems with regard to its water environment [1,2,3]. In order to further protect the water ecological environment, it is necessary to study the water environmental capacity (WEC), which refers to the maximum amount of pollutants that can be contained in a water body while maintaining normal function [6,7], based on hydraulic modeling that can calculate the flow direction, flow volume, and water quality transport [8]. Considering the synergetic influence of point and surface sources, a nonlinear optimization allocation model was used to calculate the WEC with the genetic algorithm based on controlled section water quality standards [23]. As a professional modeling software, MIKE takes into account both topography and hydrological conditions to improve the hydrodynamic simulation accuracy and further improve the water quality simulation accuracy. A MIKE 11 model was established to study the WEC of Qinhuai

Methods

Results

Discussion

Conclusion