Architectures,Relationships between Discharges and Width/depth Ratios of Stream Cross Profiles, and Stream Powers of Anastomosing Rrivers

As a new type of rivers, anastomosing river has been concerned by researchers although some questions about it was not clear for understanding it. This paper discusses the river architectures, relationships between width/depth ratios of stream cross sections and discharges, and stream powers of anastomosing rivers according to references and obtained data recently. It is helpful to researchers who is interested in this river pattern to develop the theory for it. Many aspects of anastomosing river appear particular characteristics compared with other river patterns. In the planform architectures, the multiple channels joining each other enclose flood basins on which vegetation, swamps and lakes develop basically. Longitudinal gradients of the channels are very low while the channel width/depth ratios are smaller than 40. In the depositional architectures of cross profiles, some isolated sand bodies of channel deposits are floating in the mud bodies of flood basins. In the half logarithm diagram of width/depth ratios of stream cross profiles vs. discharges, the scatters of anastomosing rivers are below compared with that of other river patterns. The stream powers of anastomosing rivers are very low compared with the old trunk channel from which it diverted because the channel gradients and discharges of every anastomosing channel are smaller than that of the old trunk channel. The specific stream power of the anastomosing channels: eastern Songzi River, western Songzi River, Hudu River, Ouchi River, northern Ouchi River and Songliheliu River are 3.0 W/m 2, 5.5 W/m 2, 2.8 W/m 2, 6.4 W/m 2, 3.7 W/m 2 and 2.7 W/m 2, respectively. Obviously, all of them are smaller than 10 W/m 2. But the specific stream power of anabranched Changjiang trunk channel is 140 W/m 2. All of the characteristics of anastomosing rivers indicate that this river pattern is different from the anabranched rivers represented by the lower Changjiang River, especially from other river patterns.