Beach scarps are nearly vertical seaward facing sandy cliffs within the cross-shore beach profile. These features are often associated with eroding (nourished) coastlines and can reach heights of O(2–3 m). An analysis of a six-year dataset of beach scarp presence at the nourished Sand Engine beach shows that the formation of beach scarps at the nourishment is linked to mildly erosive (summer storm) conditions, whereas destruction is often related to extremely erosive (winter storm) conditions. Additional experiments were carried out showing the formation, migration, and destruction of scarps from artificially constructed mounds with linear slopes. The field experiments show that steep initial slopes are more susceptible to beach scarp formation. Video observations at these experiments show that the scarp toe level, where the vertical slope meets the gently sloping beach, is related to the high wave runup events. The commonly used 2% exceedance wave runup estimates can therefore be used to predict the final elevation of the scarp toe. The strong connection of maximum runup elevation with the scarp toe elevation provides a direct relation between the final scarp height through nourishment platform height and hydrodynamic conditions. High platform nourishments will promote the formation of beach scarps and steep initial profiles increase the speed at which scarps form. This study suggests that by adjusting the design of beach nourishments, beach scarp formation and persistency can be limited by regulating the natural destruction of these features.@en

Quantification of human impact on water, sediment, and nutrient fluxes at the global scale demands characterization of reservoirs with an accuracy that is presently unavailable. This letter presents a new method, based on virtual dam placement, to make accurate estimations of area-volume relationships of large reservoirs, using solely readily available elevation data. The new method is based on regional similarity of area-volume relationships. The essence of the method is that virtual reservoirs are created in the vicinity of an existing reservoir to derive area-volume relationships for the existing reservoir. The derived area-volume relationships reproduced in situ bathymetric data well. An intercomparison for twelve reservoirs resulted in an average R² = 0.93. This is a significant improvement on estimates using the best existing global regression model, which gives R² = 0.54 for the same set of reservoirs.

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