Abstract: This paper analyzes the changes in flow diversion from the Jingjiang River to the Dongting Lake
in the recent sixty years, and demonstrates the causes of these changes: extra-large floods, construction of
lower Jingjiang cut-off project, and operation of the Gezhouba reservoir and Three Gorges reservoir. The
changes in the diverted flows through the Jingjiang Three Outlets showed significantly periodical behaviors,
and at each stage of such periods the diverted flows were dominated by several trend-adjusting periods and
equilibrium-adjusting periods. A deeper exploration on the causes and their effect on the adjustment of flow
diversion at the outlets reveals that the direct cause for reduction in the diverted flows was the decrease in
water level difference between the Yangtze mainstream and the Three Outlets channels before the mid 80’s,
and then it was shifted to the flow reduction in the middle Yangtze. The variation trends of flow diversion
from Jingjiang to Dongting were predicted by using changes in control factors at different stages.