Abstract

Based on the recorded data, the channel evolution characteristics of Neimenggu reach of the Yellow River since 1986 is studied. And results show that since 1990 the sediment deposition in this reach has been increased, the water level of the same discharge has been risen, while the

bank-full discharge has been decreased. These changes caused a series of disadvantage results which include the flow-carrying capacity decreasing, the floodplain overflowing at low discharges, and the ice flood hazards increasing etc. The response relationship between the bank-full discharge，the water level of the same discharge and the water-sediment condition is also analyzed. And results indicate that the decreases in both flood peak and runoff volume are the main reasons of river channel shrinkage.

Keyword: Neimenggu reach, channel shrinkage, response, reason and result