Hydrodynamics and short-term morphodynamics of hybrid terrace configuration in a tidally restored impoundment subject to relative sea-level rise

Document Type

Article

Publication Date

6-1-2026

Abstract

We present a reduced-complexity modeling framework that couples hydrodynamics, short-term bed morphodynamics and marsh vegetation accretion to evaluate terrace-based restoration designs. Using this framework, we test a hybrid terrace configuration consisting of angled linear, chevron and circular shapes in a tidally restored impoundment. Hydrodynamics are controlled by terrace configuration, with tidal flow directed into and out of the domain, establishing simulated circulation conditions favorable for sediment retention in the back of the domain. Subaqueous depositional patterns depend on the terrace form and arrangement, while the deposition extent and magnitude are governed by the sediment type (grain size). The side slopes of the terrace configuration provide intertidal elevations favorable for marsh vegetation growth and ecosystem function. Edge habitat increases under relative sea-level rise due to vegetation-enhanced accretion. Gains in marsh edge habitat area were volumetrically equal for fresh, brackish and saline conditions but were variably distributed over subtidal, intertidal and supratidal elevations. Elevation capital produced through vegetation-enhanced marsh accretion is greatest for fresh species due to greater biomass productivity, followed by salt-tolerant brackish species, while saline marsh vegetation demonstrated greater stability of mature productivity under rising sea level. Homeostatic marsh vegetation along the terrace edges provides multiple ecological benefits, including sediment retention, habitat expansion and structural support for invertebrates, nekton and waterbirds. Our results demonstrate the reduced-complexity modeling of terrace designs can be used by restoration practitioners to assess physical and ecological outcomes to develop management plants to sustain wetland health.

Publication Source (Journal or Book title)

Ecological Engineering

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