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Submarine flows carve canyons into continental shelves, yet the conditions and events responsible for canyon incision are incompletely understood. Coarse sediment flux has been shown to promote terrestrial bedrock incision via abrasion in rivers, but similar processes in submarine canyons have yet to be systematically documented. We use repeat bathymetry, provenance analysis, wave modeling, and channel network analysis to show that longshore sheltering and wave focusing by the Delgada submarine canyon induce sediment accumulation and elevated wave shear stresses in its headwall region that frequently mobilize coarse bed material. These mobilizations scour bedrock in the headwall and generate abrasive turbidity currents that work to carve the canyon's active channel into bedrock. These findings highlight an important positive feedback between submarine canyons, waves, and sediment supply and suggest that submarine canyons adjacent to wave‐dominated, coarse sediment‐rich coastlines seek the shorelinethrough headward incision. The carving of submarine canyons into the continental shelf is poorly understood relative to river valleys on land. We studied a submarine canyon in Northern California that is connected through littoral transport to river sediment using a combination of seafloor mapping, tracking sediments using their chemical elements, and simulating waves and currents to better understand which processes are responsible for canyon erosion. Our findings suggest that canyon focusing of wave energy and an abundant supply of coarse sediment cause erosion at the canyon's head. This finding helps explain why submarine canyon channel networks erode toward shore and predicts that canyons near mountain ranges will preferentially remain connected the shoreline. Repeat sonar surveys and sedimentary provenance document sediment transport and erosion in Delgada submarine canyon, Northern CaliforniaHydrodynamic modeling and littoral budgets suggest that coarse sediment is mobilized by waves in the canyon head, triggering turbidity currentsSediment supply and wave focusing promote erosion of submarine canyons along tectonic coasts, encouraging littoral to deep sea connectivity

Barrier islands are especially vulnerable to hurricanes and other large storms, owing to their mobile composition, low elevations, and detachment from the mainland. Conceptual models of barrier‐island evolution emphasize ocean‐side processes that drive landward migration through overwash, inlet migration, and aeolian transport. In contrast, we found that the impact of Hurricane Dorian (2019) on North Core Banks, a 36‐km barrier island on the Outer Banks of North Carolina, was primarily driven by inundation of the island from Pamlico Sound, as evidenced by storm‐surge model results and observations of high‐water marks and wrack lines. Analysis of photogrammetry products from aerial imagery collected before and after the storm indicate the loss of about 18% of the subaerial volume of the island through the formation of over 80 erosional washout channels extending from the marsh and washover platform, through gaps in the foredunes, to the shoreline. The washout channels were largely co‐located with washover fans deposited by earlier events. Net seaward export of sediment resulted in the formation of deltaic bars offshore of the channels, which became part of the post‐storm berm recovery by onshore bar migration and partial filling of the washouts with washover deposits within 2 months. This event represents a volumetric setback in the overwash/rollover behavior required for barrier transgression, but the new ponds and lowland habitats may provide beneficial habit for endangered species and will likely persist for years. As sea level rises, barrier islands tend to migrate toward land, helped by storms that move sand from the ocean to the back side. In rarer events, such as Hurricane Dorian (2019), storms can transport sand from the back side to the ocean. Using overlapping photos collected from a plane, we created 3‐D elevation maps and stitched‐together photo mosaics of North Core Banks, North Carolina, immediately before and after Hurricane Dorian, and then once a month for 3 months afterward, to document the erosion and recovery of the beach and barrier island. We found major changes. During the storm, abnormally high water levels in Pamlico and Core Sounds flooded the island and created distinct channels as water drained from the sound side into the Atlantic Ocean. This process, called outwash, moved 18% of the island sand into the ocean over the course of a few hours. The maps also showed the initial stages of a recovery process, as beach sand was moved by ocean waves and plugged the channels, creating new, and semi‐permanent, habitats within the barrier island. Events such as Hurricane Dorian may slow the typical migration process of barrier islands and change the landscape for years to come. Wind‐driven surge from Pamlico Sound inundated the barrier island of North Core Banks during Hurricane DorianSeaward‐directed flow (outwash) through gaps in the dunes eroded about 18% of the island volume, mostly from antecedent washover depositsThis event represents a setback for barrier transgression but has created beneficial habitat for endangered species Wind‐driven surge from Pamlico Sound inundated the barrier island of North Core Banks during Hurricane Dorian Seaward‐directed flow (outwash) through gaps in the dunes eroded about 18% of the island volume, mostly from antecedent washover deposits This event represents a setback for barrier transgression but has created beneficial habitat for endangered species

This paper introduces a method for determining spatially‐distributed, 2‐D bedload rates using repeat, high‐resolution surveys of the bed topography. As opposed to existing methods, bedform parameters and bedload rates are computed from bed elevation profiles interpolated along the local bedform velocities. The bedform velocity fields are computed applying Large‐Scale Particle Image Velocimetry, initially developed for surface velocity measurements, to pairs of successive Digital Elevation Models (DEMs). The bathymetry data are interpolated along the direction of each bedform velocity and the mean height of the closest bedform is computed. The dune shape factor is also evaluated along each bedform direction of travel. The local bedload fluxes can be computed by multiplying the bedform velocity by its mean height averaged over the successive two DEMs, and they can be time‐averaged over a series of DEM pairs. This method is applied to a high‐resolution acoustical survey of an approximately 300 m long by 40 m wide reach of the Colorado River in Grand Canyon upstream from Diamond Creek, USA. The repeat period was about 6–10 min and bed elevation was interpolated every 0.25 m. The obtained results provide insight to the spatial and temporal variability of bedload rates, bedform parameters and bedload fluxes through cross‐sections. The method can be applied to other repeated acoustical surveys of river reaches provided that the space and time resolutions are high enough to capture the local movement of bedforms. We introduce a method for mapping bedload fluxes using repeat, high‐resolution acoustical bathymetric surveys of a river reachThe method combines cross‐correlation velocimetry and local analysis of individual bedforms along their direction of travelApplication to the Colorado River in Grand Canyon provides a proof‐of‐concept and shows the spatio‐temporal variability of local bedload We introduce a method for mapping bedload fluxes using repeat, high‐resolution acoustical bathymetric surveys of a river reach The method combines cross‐correlation velocimetry and local analysis of individual bedforms along their direction of travel Application to the Colorado River in Grand Canyon provides a proof‐of‐concept and shows the spatio‐temporal variability of local bedload

The article presents a case study that considers the causes, consequences and management of coastal erosion of a gravel beach-barrier system on the south Devon coast. It reveals that coastal change is often the result of a number of processes operating at different timescales. The article discusses the key processes causing coastal erosion: sea-level rise, longshore sediment transport and storms. INSETS: Importance of Slapton barrier;Barrier evolution.