Identification and assessment of potential water quality impact factors for drinking-water reservoirs.

Qing Gu,Ke Wang,Jun Li,Yi Lin,Yang Hong,Muye Gan,Jinsong Deng,Ligang Ma

doi:10.3390/ijerph110606069

Abstract

Various reservoirs have been serving as the most important drinking water sources in Zhejiang Province, China, due to the uneven distribution of precipitation and severe river pollution. Unfortunately, rapid urbanization and industrialization have been continuously challenging the water quality of the drinking-water reservoirs. The identification and assessment of potential impacts is indispensable in water resource management and protection. This study investigates the drinking water reservoirs in Zhejiang Province to better understand the potential impact on water quality. Altogether seventy-three typical drinking reservoirs in Zhejiang Province encompassing various water storage levels were selected and evaluated. Using fifty-two reservoirs as training samples, the classification and regression tree (CART) method and sixteen comprehensive variables, including six sub-sets (land use, population, socio-economy, geographical features, inherent characteristics, and climate), were adopted to establish a decision-making model for identifying and assessing their potential impacts on drinking-water quality. The water quality class of the remaining twenty-one reservoirs was then predicted and tested based on the decision-making model, resulting in a water quality class attribution accuracy of 81.0%. Based on the decision rules and quantitative importance of the independent variables, industrial emissions was identified as the most important factor influencing the water quality of reservoirs; land use and human habitation also had a substantial impact on water quality. The results of this study provide insights into the factors impacting the water quality of reservoirs as well as basic information for protecting reservoir water resources.

Highlights

Due to the uneven spatiotemporal distribution of precipitation and the severe deterioration of river water quality, various reservoirs have been functioning for years as the most important sources of drinking water in Zhejiang Province
The remaining parameters were excluded from the rules, not because they had no relation with the water quality of the reservoirs but because they did not significantly affect the water quality compared with the parameters listed above, which masked their effect
The classification and regression tree (CART) decision tree method was employed to estimate the classes of reservoir water quality based on a set of parameters, and a reasonable accuracy was obtained

Summary

Introduction

Due to the uneven spatiotemporal distribution of precipitation and the severe deterioration of river water quality, various reservoirs have been functioning for years as the most important sources of drinking water in Zhejiang Province. The drinking water supply derived from approximately 500 reservoirs supports approximately 70% of the population in Zhejiang Province [2]. Monitoring data has indicated that the overall status of the water quality of drinking water source reservoirs is favorable in Zhejiang; a number of reservoirs have been subject to increasing pressure and degradation, with a recent deterioration trend [4]. Sewage discharges have increased with the continuing economic development and urban construction, severely damaging the reservoir environment and affecting reservoir function. A better understanding of the status of the water quality of drinking water reservoirs and the factors that impact water quality is urgently needed

Methods

Results

Discussion

Conclusion