Understanding morphodynamic mechanics controlling evolution of meandering rivers
A meandering river is a single-thread channel with variable degrees of wiggling. In the Qinghai-Tibet Plateau (QTP), meandering rivers, regardless of their locations, share two morphological characteristics. First, their planform is almost always featured by high sinuosity. Second, their banks have widely subject to cantilever bank erosion due to the composite structure of bank profiles. While neither characteristic is unique as it may be found in meandering rivers of other regions, understanding mechanisms of their evolution and future evolutional trajectories is important in both theory and practice, because these rivers seem to have not affected by environmental shift caused by climate change including glacier retreat, permafrost shrinking, increasing upland erosion, and degradation of indigenous land types (peatland). I argue that the evolution mechanisms of these meandering rivers are controlled by two fundamental processes: (1) cutoff and (2) cantilever bank erosion. In almost all meandering rivers in the QTP, meander bend cutoff is dominated by neck cutoff, which is well known that its occurrence takes longer time than more commonly seen chute cutoff. Along the banks of these meandering rivers, cantilever arms with variable lengths are easily discernable. The collapsed cantilever bodies are also widely distributed at the toe of channel banks. My overarching goal is to find answers for explaining what factors or their compound effects dominate evolution of these meandering rivers, if not climate change. My studies are focusing on two areas:
- Morphodynamic principles controlling neck cutoff
- Hydraulic and morphological mechanisms of bank collapse and deposition
| The Black River (a tributary) | The Lanmucuo River | The Upper Nu River |
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Although image analysis and modeling simulation are typical ways of achieving research goals in this area, field campaign and measurements are essential. Here are some examples:
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