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.