Abstract:

To reveal the formation and evolutionary patterns of typical meandering river morphology in the main stream of the Tarim River, this study used remote-sensing images and overlaying techniques to summarize the types of planform changes in the river boundaries of the middle reach of Tarim River from Wusiman to Aqike over the past decade. Moreover, integrating measured cross-sections and hydrological data, river regime analysis was employed to evaluate the stability of river cross-sections at different times. The results are as follows: 1) The planform geometric evolution of the middle reach from Wusiman to Aqike can be categorized into four single patterns (positive shift, negative shift, extension, and contraction) and four combined patterns (positive shift plus extension, positive shift plus contraction, negative shift plus extension, and negative shift plus contraction). Among them, the positive shift plus extension pattern is the most prevalent in the study reach. 2) Morphological parameters, namely the offset degree and widening degree, along with their calculation methods, were proposed to depict the main types of planform evolution in river channels. Annual discharge was found to be the primary factor influencing the offset degree, followed by the annual sediment transport and bedload discharge. Flood was identified as the key factor affecting the widening degree. 3) In recent years, the hydraulic geometric relation coefficient has increased, suggesting an enhanced longitudinal stability of the riverbed. Meanwhile, the transverse stability of the riverbed has also improved along the study reach. This research offers significant reference for flood control engineering and river channel regulation of meandering rivers in the middle reach of the Tarim River.

Key words: meandering river channel, river evolution, hydraulic geometric relation, flood protection works, river regulation, Tarim River