摘要: Magnitude-frequency analysis of gauging station records (1950-1982) on the Lower Mississippi shows that there is a clearly defined dominant flow of about 30,000 cu m/s. This lies within an effective range of channel-forming flows ... 展开 Magnitude-frequency analysis of gauging station records (1950-1982) on the Lower Mississippi shows that there is a clearly defined dominant flow of about 30,000 cu m/s. This lies within an effective range of channel-forming flows between 17,000 and 40,000 cu m/s, which are responsible for transporting a disproportionately large percentage of the sediment load. The 33-year period of record is sufficiently long that the occurrence of an extreme high-flow event does not significantly change these results. Hydrographic survey data, long- profile records, and stage-discharge relationships from calibrated one- dimensional flow models indicate that the dominant discharge corresponds to 'bar-full' discharge on the lower Mississippi and that the effective range of flows occurs between the stage that just tops mid-channel bars and that which significantly overtops the bank. Historical trends in bar growth suggest that bar-top elevations have generally risen to the dominant flow elevation over the last 30 years. 收起