Short-term Volumetric Changes of Berm and Beachface during Storm Calming

Abstract

Bugajny, N. and Furmańczyk, K., 2020. Short-term volumetric changes of berm and beachface during storm calming. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 398–402. Coconut Creek (Florida), ISSN 0749-0208.The storm calming coastal processes are presented in the paper. Within these hydrodynamic conditions, the most intensive changes take place on the berm, the beachface and the nearshore, where erosion and accumulation processes are observed. This research was carried out along an approx. 300 m long section of the dune coast of the southern Baltic Sea, in the area of Dziwnow Spit. The measurements were taken using GPS RTK within four days, twice a day. Consecutive profiles were located in about 20 m distance from each other covering the most dynamic part of the beach and the shallow bottom to a depth of about 0.5 m. In order to compare volumetric changes in the profiles, a 1 m grid along every profile was created. Next, a rate of those changes was calculated for each grid. During the storm calming, the significant wave height changed from 1.0 m to 0.2 m from SW to SE direction, and the water level dropped down by 20 cm. A diversified rate of volumetric changes of the beach in time and space was identified, depending on profile location along the coast. Also, temporal and spatial differentiation of the beach volumetric change rate was found, depending on profile location and its parts. The beach accumulation rate did not exceed 0.012 m3/m/h, and erosion - 0.019 m3/m/h, while in the shallow bottom, the accumulation rate did not exceed 0.030 m3/m/h, and erosion rate - 0.020 m3/m/h. The diversity of these processes in time and space are observed and they are related to hydrodynamic conditions. The obtained results will help to understand the accumulation processes during the storm calming in non-tidal environments.