A method for estimating sediment budgets of washover deposits using digital terrain models

Abstract

Washover fans are located on small barriers in fetch‐limited micro‐tidal coastal environments in Denmark. These washover fans are formed during high‐energy storm events and we present a method to quantify their volumes and to estimate sediment exchanges between washover fans and their adjacent morphologies. We use high resolution digital terrain models (DTMs) based on light detection and ranging (LiDAR) data. We have delineated landforms using known methods of scale analysis and geomorphometric classification. We quantified volumes of the delineated landforms and estimated the related sediment budgets. These computed volumes were compared using different pre‐depositional surfaces. Finally, we assessed the sediment exchange and associated sources of sediments of the washover fans. We applied a scale analysis to determine suitable DTM resolution and focal statistics window size as input to a geomorphometric classification analysis. Landform areas and landforms were delineated using morphometric threshold values, and volumes and sediment budgets of the delineated landforms were computed using different assumptions to define the pre‐depositional surface. Resulting washover fan volumes were validated against digital elevation model (DEM) of difference (DoD) derived volumes. Sediment budgets were derived from representative volumes of the washover fans and adjacent berms. We show that quantification of washover features derived from DTMs, using geomorphometric analysis is feasible and that the presented approach provides estimates of washover deposit volumes with an accuracy between 1% and 28% compared to control volumes. © 2021 John Wiley & Sons, Ltd.

Volume Estimation From Planform Characteristics of Washover Morphology

“…We measured washover morphometry, including volume, for 148 deposits in natural (non‐built) and built settings along the barrier coastline of New Jersey, USA, by taking the difference between lidar‐derived DEMs bracketing Hurricane Sandy (2012). We also collated 35 measurements of washover morphometry, including volume, reported in the literature by six different studies, sampling different storm events in different non‐built barrier settings (Carruthers et al., 2013; Hansen et al., 2021; Rodriguez et al., 2020; Williams, 2015; Williams & Rains, 2022), including a carbonate system (Jamison‐Todd et al., 2020). Lidar surfaces were downloaded from the NOAA Digital Coast Data Access Viewer (NOAA, 2022).…”

Volume estimation from planform characteristics of washover morphology

“…We measured washover morphometry, including volume, for 148 deposits in natural (non-built) and built settings along the barrier coastline of New Jersey, USA, by taking the difference between lidar-derived DEMs bracketing Hurricane Sandy (2012). We also collated 35 measurements of washover morphometry, including volume, reported in the literature by six different studies, sampling different storm events in different non-built barrier settings (Carruthers et al, 2013;Hansen et al, 2021;Rodriguez et al, 2020;Williams, 2015;Williams & Rains, 2022), including a carbonate system (Jamison-Todd et al, 2020). Lidar surfaces were downloaded from the NOAA Digital Coast Data Access Viewer (NOAA, 2022).…”