Abstract: Water level, as a key hydrological factor of Poyang Lake, plays a crucial role in determining the hydro-dynamic process and water quality changes of the lake. Based on the monitoring data on water level and water quality of the main lake area of Poyang Lake and the dish-shaped sub-lake from 2014 to 2015, we examined the characteristics about the changes of the water level and major parameters of water quality within the year, and defined the characteristics about the response of water quality to water level. The results showed that: 1) during the wet season, the sub-lake is connected with the main lake area, and there is a linear correlation between water level of the sub-lake and that of the main lake area. During the dry season, the water level of the sub-lake is higher than that of the main lake area, the coefficient of variation for average monthly water level within the year in the main lake area was calculated to be 0.13, while that in the sub-lake was 0.08. 2) During the wet season, the N/P ratio in the main lake area and the sub-lake was recorded to be 19.29 and 46.27 respectively, while the figure was 17.88 and 40.39 respectively during the dry season. 3) The correlation between major water quality parameters and water level in the main lake area is significantly stronger than that in the sub-lake. The TN, NH3-N, TP and DO are found to be negatively correlated with water level in the main lake area, while there is only a correlation between pH and water level in the sub-lake. 4) During the dry season, the content of TN is high in the sub-lake, while that of TP and NH3-N is high in the main lake area. Overall, these results imply that optimizing water level management during the dry season can help effectively reduce the risk of eutrophication of Poyang Lake.
Key words：water level; water quality; dish-shaped lake; Poyang Lake