Study on the Reservoir Water Quality Change Rule in Northern China

Water quality index of reservoir source water were tracked during three years in a north frigid area, the effect on supplied water quality was also studied. Based on the analysis of the monitoring data during the same season, the reservoir source water had typical and seasonal variation characteristics that was divided into four periods including the icebound period, spring period (or peach blossom period), stable period in summer and autumn and winter period. The icebound period was charactered by the typical low temperature and turbidity, pH and oxygen consumption decreased gradually showed that the gradually anaerobic trend existed in the reservoir. In May as the reservoir completely thawed, upstream water inflow and the total pollutant in the reservoir gradually increased, but the bottom of reservoir bottom was stable in the anaerobic state temporarily. The state completely disappeared, various index increased significantly in the middle of July. The water had high chroma characteristics, chroma and turbidity increased significantly in the summer and autumn (7-11 months), but stability of water quality was poor because of rainfall. The reservoir gradually froze after the middle of November and the flow of water decreased. The peak of chroma appeared a month later than the water temperature. Due to the water turbidity was low, and the floc was small and light, the conventional water purification process design based on removal of turbidity achieved removal of chroma through a lot dosing of coagulant.