Large‐Scale Scour in Response to Tidal Dominance in Estuaries
نویسندگان
چکیده
Channel beds in estuaries and deltas often exhibit a local depth maximum close to the river mouth. There are two known mechanisms of large-scale (i.e., >10 widths along-channel) channel bed scours: width constriction draw-down during discharge extremes, both creating flow acceleration. Here, we study potential third mechanism: tidal scour. We use 1D-morphodynamic model reproduce dynamics scours that morphologic equilibrium. A equilibrium is reached when net (seaward) sediment transport matches upstream supply along entire reach. The residual (river) current river-tide interactions create seaward transport. Herein, represent advection tide-induced suspended by flow. Tidal asymmetry typically creates landward Scours form amplified through funneling energy. simultaneously reduce interaction contribution transport, thereby maintaining When influence relatively large, convergence strong, an only obtained with scouring profile. propose predictor dependent on convergence, quantified as SB, ratio between specific peak at mouth boundary (qtide/qriver). develop if (qtide/qriver)/SB exceeds 0.3. Scour conditions were found occur globally across range scales, which allows its prediction under future changes.
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ژورنال
عنوان ژورنال: Journal Of Geophysical Research: Earth Surface
سال: 2021
ISSN: ['2169-9011', '2169-9003']
DOI: https://doi.org/10.1029/2020jf006048