Abstract: Beiluohe River, a tributary of the Huanghe River(Yellow River), is located in the middle region of the Yellow River basin. This branch is characterized by its high sediment yield. Its annual mean discharge is 25 m3/s and its sediment concentration is measured at 128 kg/m3. The river has a bed slope of 2. The mean diameter of the suspended sediment is 0.036mm. Both of the bed slope and the sediment composition are similar to those at the lower reaches of the Yellow River.Since most of the sediment (72% of the sediments are produced annually in long term average) are transported by floods with a concentration of higher than 300 kg/m3(sometime it can be as high as 800-900kg/m3) . bank slumping associated with lower sediment concentration flow occurs rarely. In contrary, the sediment concentration is very low during non-flood season. However, if the sediment transport is described by the empirical equation Qs=kQm for all situations,the value of m for this river can be as high as 5. 0. which is the condition for meander river to form. Since he hyper-concentrated flow occurs during flood season. sediments are mainly deposited on the flood plain and the channel is usually deepened in this period. This character is in favor of not only the sediment transport during flood season but also the formation of a meander river.In summary, having narrow and deep channel is a necessary boundary condition for a river to become a meander one.

Key words: Lower Beiluohe River, hyperconcentrated floods, river channel adjustment