Statistical Analysis Characterizing Differences in Planform Geometry between Wetland and Alluvial Rivers

It is well known that natural meandering rivers have very distinct patterns of sinuosity. These are often divided into two types: alluvial rivers and wetland/peatland rivers. Each channel pattern is formed under the influence of the relevant dominant fluvial processes. In the case of alluvial rivers, channel pattern forms through the processes of erosion, deposition, and transport of sediment. On the other hand, the channel patterns of wetland rivers appear to depend more strongly on bank and bed erosion. These different formation mechanisms of the two river types may account for the milder, smooth curvature of the former type and the more zigzag geometry of the latter type. Several theoretical studies gave powerful mathematical descriptions of meandering river processes. They have mainly succeeded in explaining the formative mechanisms of alluvial rivers. However, the formative mechanisms of wetland rivers are not sufficiently understood. From engineering and geomorphic points of view, understanding the differences in formation mechanism between these two types of meandering rivers is necessary to quantify meander growth. The differences in planform are illustrated here. The results can be applied to develop conservation and restoration methods for wetlands, which store carbon dioxide and nitrogen. This study discusses geometric characteristics with reference to satellite radar images of about 50 rivers (including the two types of meandering rivers mentioned above) around the world, and characterizes the differences between these two types of meandering rivers.