Impacts of Engineered Diversions and Natural Avulsions on Delta-Lobe Stability
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Reduced sediment supply and rising sea levels are driving land submergence on deltas worldwide, motivating engineering practices that divert water and sediment to sustain coastal landforms. However, lobe response following channel abandonment by diversions has not been constrained by field-scale studies. Herein, avulsion and engineered diversion scenarios are explored for the Huanghe delta (China), where three lobes were abandoned in the last 40 yr. Two lobes were completely cut off by diversions, and one naturally by an avulsion. Shoreline retreat rates are strikingly different: ∼400 m/yr for diverted lobes and ∼90 m/yr for avulsed lobe. We hypothesize that this variability is linked to vegetal cover across lobes, and therefore the capacity to buffer hydrodynamic reworking of shoreface sediment. Furthermore, the vegetal cover is related to lobe salinity and elevation, which vary by abandonment style. We offer this as a case study to inform about the efficacy of future delta diversions.
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Carlson, Brandee N., Nittrouer, Jeffrey A., Swanson, Travis E., et al.. "Impacts of Engineered Diversions and Natural Avulsions on Delta-Lobe Stability." Geophysical Research Letters, 48, no. 13 (2021) Wiley: https://doi.org/10.1029/2021GL092438.