Quantitative impacts of population on river water quality in the Jinshui River basin of the South Qinling Mts., China

Abstract

Increasing population is generally responsible for the degraded river ecosystem. Using regression models and mathematical functions, the research quantitatively estimated the population and elevational gradient effects on river water quality during nine surveys from 2006 to 2008 in the Jinshui River basin of the South Qinling Mts., China. The total factor scores at 11 different sampling sites were calculated in factor analysis and first used as pollution index to represent the water quality levels. Population and elevational gradient both significantly linked with most water quality variables and pollution index in correlation analysis and explained 36.5-77.8 % of the total variances in regression analysis, indicating that human activities were gradually frequent with population growth and affected the input and output of pollutants in river water. On the basis of regression models and quadratic functions among population, elevational gradient, and pollution index, the population capacity of the river basin was estimated as 1815 people, and the threshold value of elevation was calculated as 1174 m. The results of multivariate linear models further confirmed that population and population distribution had direct influences on river water quality. This study will facilitate the ecosystem management for mountainous streams and provide quantitative models for understanding and mitigating human impacts on river system.

Impact of Population Growth on the Water Quality of Natural Water Bodies

“…Further, less correlation between population density and NO 3 − has been shown in other research conducted in Sierra Nevada, California by Dylan S. Ahearn et al [29]. The research conducted on the Jinshui River Basin of the South Qinling Mountains, China, predicted the most correlated water quality parameters, which have strong correlation with population, by defining the linear equations [10]. Comparison of the results for both rivers clearly illustrates the relationship between population and the water quality of the river basin.…”

“…Therefore, the POP-2 range is suitable for maintaining water quality in class C. Taken together, a watershed with a population density of less than 2375, helps to maintain water quality at a higher level with the classification classes A and B in the river basin, whereas a population density less than 2672 is helpful with regard to class C. This proposed population density can be taken into account when determining the carrying population density of the watersheds. Numerous studies that have been conducted on water pollution in river basins have identified a high correlation between population and water quality parameters [1,4,9,10]. The present study further evaluated the effects and defined threshold values for population density with respect to the classification of water quality in river basins.…”

“…The evaluation and mitigation of the contamination and control of the non-point source pollution is more difficult than that of the point source pollution. Furthermore, contamination of the catchment areas of a river has been increasing due to urbanization near the many rivers [5,10]. Identifying the level of impact of non-point source pollution is very essential to facilitating the watershed ecosystem.…”

“…Research conducted on the Jinshui River by Hongmei Bu et al proposed a method to find the threshold value of population by a quadratic equation of the pollution index and population [10]. The threshold values of population was based on the total factor score of the sample site with the best water quality.…”

“…This may be caused by improperly planned urbanization or uncontrolled development [9]. This has been made evident by Hongmei Bu et al's work conducted on the Jinshui River in China, where they reported that the population had a significant impact on most of the water quality parameters [10]. Thereby, they identified a population capacity for the river basin, and estimated the possible increase of population.…”