Channel Processes Disconnectivity in Rivers Hydromorphology

Abstract

The present paper deals with five main structural levels of channel processes and channel patterns due to disconnectivity of fluvial processes. River braiding is related to existence of point, bar, channel (island), anabranching and large distributary channels (located in the deltas of large and largest rivers). Meandering is related to sinuosity of the flow and formation of complex loop and large meanders, the dimensions of which are larger than those corresponding to the water content of the river, and the meanders of the meandering belts. Due to the instability of the straight flow, the structural levels of the straight single channel are distinguished by their size: pool hollows on the riffles, reaches between adjacent bends and segments of braided channel, sections between single branches and stretched stretch areas along the bedrock banks or in the incised channel. Each structural level is related to the previous one forming scaling sequence (middle and side channels are the basis for the formation of branches and bends, etc.), representing genetic series, although in some cases they may have a different origin (intra-floodplain intercepts, relics of delta branches, etc.). The meandering process happens over various scales in both braided and straight channels. The formation of structural levels is governed by river size, geology, effective discharges and local drivers.