Reshaping of San Jose Island, TX, USA, by Unconfined Washover and Channelized Washout During Hurricane Harvey
Year: 2026
Type: article
Abstract: Hurricane Harvey (2017) produced 31 net‐erosional washout channels on San Jose Island, Texas, USA, where offshore‐directed flows cut through two dune ridges and the beach. Channel growth was affected by natural, pre‐existing aeolian topography, rather than prior washover channels or infrastructure. We investigate how offshore directed outwash, initially unconfined across the back‐barrier, was focused by pre‐storm topography. This work assesses their initiation, morphology, and 8 years of recovery using pre‐ and post‐storm LiDAR, field surveys, hydrodynamic modeling, sediment transport estimates, and satellite imagery. Pre‐storm dune topography was sufficient to restrict landward overwash in the early phases of the storm. Pre‐storm LiDAR indicates that washout channel locations corresponded to pre‐existing topographic lows, indicating that outwash preferentially exploited swales and wind gaps. ANUGA hydrodynamic simulations revealed that dune topography strongly shaped water‐surface gradients and flow velocities, concentrating flow into incipient channels. Sediment transport calculations matched erosion volumes, indicating that channel growth was limited by outwash duration and can be approximated using steady‐flow unidirectional transport algorithms. Channels widened predictably with landward elongation and displayed dendritic headcuts and signatures of flow capture analogous to dam‐break flows, gullies, and interacting channel networks, offering parallels to better‐studied environments. Recovery has been slow: berm rebuilding began immediately but slowed after 6 months, while dune regrowth has lagged. Timescales are at least three orders of magnitude longer than incision, leaving Harvey's channels as persistent, low‐elevation conduits to the island interior. These new pathways highlight how storm‐driven outwash reshapes barrier morphology and reduces thresholds required for future cross‐island flooding.
DOI: 10.1029/2025jf008876
Language: English
Topic: Coastal and Marine Dynamics
Subfield: Earth-Surface Processes
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,070
OpenAlex ID: W4414601524
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