A study of spatial and temporal water quality variation in Liangzi Lake

Liangzi Lake is the second largest fresh water lake in Hubei Province. It is of important significance to understand the temporal and spatial variation of the lake water quality for construction of Liangzi Lake and neighboring cities. The sampling data of water quality during spring, summer, autumn and winter were studied, and the geostatistical analysis used to analyze the temporal and spatial characteristics of water quality factors, including total nitrogen (TN), total phosphorus (TP), ammonia nitrogen ($NH_{4}^{+}$-N) and permanganate index (COD_Mn). The results showed that the TN concentrations in water in winter were higher than the spring, with higher values in north area. The overall annual variation of TP was small, decreasing from east to west. The $NH_{4}^{+}$-N was higher in winter compared with summer, decreasing from east to west, and in individual regions the concentration was higher in winter than in autumn. The COD_Mn was generally low in spring and winter and higher the summer and the autumn, mainly in the middle of the western and eastern lake. Therefore, temporally the water quality in winter and spring was better than summer and autumn, and spatially the water quality was better in the center of lake but worse in the east estuary of the lake and the lake inlets.