Abstract: In order to explore the flow characteristics of hydrological stations after reservoir impoundment of Three Gorges project, we took Yichang station as an example and analyzed the characteristics of water level and flood according to measured data from 2003 to 2014.Results showed that water level fluctuation intensified and water level decreased under the same discharge, the highest annual water level declined and the lowest water level raised. The duration of mid-low water level increased and its discharge varied in daily scale; Moreover, annual minimum discharge tended to increase and gradually kept stable at 6 000 m³/s. Since annual maximum discharge was under the control of regulation and impoundment of Three Gorges reservoir, the duration of flood peak lasted longer and annual discharge varied with longer low flow period and shorter flood period. Relationship between mid-low water level and discharge showed a tendency of many single lines. Therefore, according to current characteristics of water flow, we should adjust the methods of collecting water level and discharge data to meet the need of compilation.

Key words: Three Gorges project, impoundment, Yichang station, flow characteristics, test measures