4.2.1 Changes in Flow in Lake
Fig 5 shows that the annual inflow of Poyang lake from 1977 to 2020 has an increasing trend. MK trend test shows that the increasing trend is insignificant (Z =1.10). Mk mutation test shows that the change point was in 1992 and 2003. Pearson analysis tested the relationship between lake area and inflow. The result shows that the coefficient in the flood season was 0.38 and in the dry season was 0.08. The correlation coefficient in flood season passed the 99% level test.
However, Fig 6 shows that the annual net outflow of Poyang lake from 1977 to 2020 also has an increasing trend. Mk trend test confirms that the increasing trend was lower than inflow runoff (coefficient 0.54), and the Mk mutation test also shows that the change point was insignificant. The Pearson analysis tested the relationship between lake area and net outflow. Results showed a correlation coefficient between lake area and runoff in the dry season was 0.09. The correlation coefficient in flood season was 0.48, indicating a correlation between lake area and net outflow, and the consequences passed the 99% level test. Test results demonstrated that flood season lake areas have an associative relationship with the lake flow.