The Changing Water Quality Characteristics from Urban Drinking Water Sources in Guangdong, China

Abstract

Studies regarding the temporal-spatial variability of water source quality are crucial for protecting urban drinking water and for urban planning. With 41 typical drinking water sources in Guangdong Province as the research object, this study investigated temporal-spatial trend of different kinds of water sources in different seasons, a subject that has received little attention. The water quality index (WQI) method was used to study the quality of water sources, and the seasonal Kendall testing method was used to analyze the trends in changing water quality. The following results were obtained: (1) Overall, 22 water sources showed tendencies towards improvement and 13 showed a steady trend towards improvement. In addition, 6 sources faced water quality deterioration problems. The quality of the water source and its variations in eastern, northern and western Guangdong are satisfactory. However, the water sources with the poorest quality or that exhibited deteriorative trends were concentrated in the Pearl River Delta. (2) More water sources exhibited improving quality during the non-flood season than during the flood season. In addition, this effect was more pronounced in river-type source water than in reservoir-type source waters. During the flood season, 5 water sources exhibited deteriorative trends. Of these water sources, 3 were river-type. In addition, 18 water sources had improving water quality. Of these, 12 were river-type. During the non-flood season, only 2 river-type water sources exhibited a deteriorative trend. In addition, 19 water sources showed water quality improvements. Of these, 14 were river-type sources. (3) According to the calculated WQI and its temporal variations, this paper suggests that water sources in Guangdong can be classified into four groups, high WQI, saltatory WQI, fluctuant WQI, and low WQI. In addition, the WQI method and seasonal Kendall testing methods are appropriate for investigating the temporal-spatial variability of water source quality and can provide guidance for regional water source planning.