Straight-line non-branching channels: morphological diversity and typifi cation

Relatively straight non-branching channels account for the smallest share among all morphodynamic types of channels, which is due to the instability of the rectilinear flow movement. Recently they have become objects of study from the point of view of their morphology, dynamics and conditions of formation, including on particular rivers, due to the difficulties arising in solving water management and water transportation problems. Despite their apparent uniformity and relatively weak intensity of channel reformations, they are characterized by certain morphological variability associated mainly with the parameters of the channels, their water content, and specific conditions of formation. Rectilinear channels could form an independent type and associated morphologically homogeneous sections in a wide-floodplain, adapted and incised channel. They could also occur in the form of small sections (“insertions”) between adjacent bends in a meandering channel, in floodplainchannel branches, in the branches of conjugated and single branchings. Rectilinear “insertions” are an integral part of complex chest (trapezoidal) bends, in which they separate the upper forced bend of the channel on the approach to the leading bedrock bank or the ledge of a high, rarely flooded floodplain, and the lower bend with an upper wing near the bedrock bank. Taking into account all factors, a complete classification of rectilinear channels has been elaborated. The conditions of their formation and specific features of their deformations have been defined, as well as possibilities of the optimal management of channel processes to ensure the stability of waterways and hydraulic structures, and the operation of water management facilities.