Abstract: The three outlets of Jingjiang river, as the link between Dongting Lake and Jingjiang River, has always been the key point of flood control, shipping, water environment changes and water resources utilization in Dongting Lake area. In this paper, the diverted flow rates from Jingjiang River in the presence and in the absence of the Three Gorges Reservoir were calculated using a flow diversion model of the three outlets of Jingjiang River. The observed and corresponding naturalized data of daily flow rate at Zhicheng station during 2008-2015 were taken as the model inputs. Moreover, the influences of the Three Gorges Reservoir on the runoff, diversion ratio and diverted flow of the three outlets (including the comprehensive influence of runoff regulation and river channel adjustment) were discussed, and in particular, the influence of river channel adjustment on the runoff of the three outlets was expounded. In the presence of the Three Gorges Project, under the comprehensive influence of runoff change and river channel topography regulation, in pre-flood season the multi-year average diverted runoff and diversion ratio increased by 28.17% and 9.59%, respectively, and the zero-flow situation of the outlets basically remained unchanged; in flood period the annual average runoff decreased by 2.11% while diversion ratio increased by 0.56%, with the zero-flow situation changed little; in post-flood season, the multi-year average diverted runoff and diversion ratio decreased by 33.87% and 19.84% respectively, with barely no change in the zero-flow situation at Songzi and Taiping whereas increased and advanced days of zero-flow at Ouchi; in dry season, the multi-year average diverted runoff increased by 8.60%, the multi-year average diversion ratio decreased by 2.93%, and the multi-year average number of days of zero decreased by 30.43 days and 6.80 days respectively at Songzi and Ouchi, but increased by 30.86 days at Taiping. In addition, the adjustment of river channel topography increased the runoff of Jingjiang River by 2.73% in flood season, and reduced the runoff of Jingjiang River by 16.62%, 3.10%, and 18.49% respectively in pre-flood season, pre-flood season and dry season. The research findings lay a foundation for the study of lake drought and water resources utilization and protection in the Dongting Lake area as well as the operation of Three Gorges Reservoir.

Key words: Three Gorges Reservoir, three outlets of Jingjiang River, diverted runoff, diversion ratio, zero-flow