Surface water quality change and the analysis of acting factors of Hutuo River-reach system in the urban areas of Xinzhou City in 2004-2011

Hutuo River system is the most important drainage system for Xinzhou City( Shanxi),whose water quality has an important influence on the urban environment and the downstream areas. The paper intends to analyze the causes of the influential factors on the quality of the river by using the surface water monitoring data from 2004 to 2011,including the statistical data of water quality,the social and economic statistical data and the monitoring data in terms of the sewage treatment plants. The results of our study show that the trend of surface water pollution of the river system can be divided into two stages,involving the water quality deterioration and the water quality improvement. Generally speaking,the turning point took place in 2009,when the pollution rate of the river pollutants was reduced to class Ⅳ by the national standard. The water quality in wet seasons can be said even a bit better than that in dry seasons. Furthermore,the river water,the precipitation situation and the water quality can be said negatively correlated, with the correlation coefficients being0. 675 and 0. 532,respectively( p 0. 01),though the improvement of the river water quantity and the effect of the precipitation on the river water quality was limited. After all,the water quality and the period of change should be well noted. However,the deterioration of the water quality took place mainly involved the discharge of the industrial waste since 2009,which led to the correlation coefficient reduced to 0. 689( p 0. 01). And,then,the correlation coefficient was reduced to 0. 465( p 0. 05) as a result of the domestic sewage discharge. Though living sewage emission accounts for a greater part than that of industrial sewage,it has been made easier for the standard operation of sewage treatment plant that promoted the river water quality further improved since 2009. Since the sewage rate and the effluent water quality rate are the premise to the continuous improvement to ensure the water quality in the region. Further improvement of the river water quality would have much to do with the standard operation in the sewage treatment plants in the area.