TY - JOUR

T1 - Effect of Variations in Water Level and Wave Steepness on the Robustness of Wave Overtopping Estimation

AU - Kerpen, Nils B.

AU - Daemrich, Karl Friedrich

AU - Lojek, Oliver

AU - Schlurmann, Torsten

N1 - Funding text 1: This research received no external funding. The publication fees are sponsored by SINTEF Ocean. The authors gratefully acknowledge the support of Susanne Huxhage who gave significant support with the conduction of the hydraulic model tests as part of her student thesis.

PY - 2020/1/21

Y1 - 2020/1/21

N2 - The wave overtopping discharge at coastal defense structures is directly linked to the freeboard height. By means of physical modelling, experiments on wave overtopping volumes at sloped coastal structures are customarily determined for constant water levels and static wave steepness conditions (e.g., specific wave spectrum). These experiments are the basis for the formulation of empirically derived and widely acknowledged wave overtopping estimations for practical design purposes. By analysis and laboratory reproduction of typical features from exemplarily regarded real storm surge time series in German coastal waters, the role of non-stationary water level and wave steepness were analyzed and adjusted in experiments. The robustness of wave overtopping estimation formulae (i.e., the capabilities and limitations of such a static projection of dynamic boundary conditions) are outlined. Therefore, the classic static approach is contrasted with data stemming from tests in which both water level and wave steepness were dynamically altered in representative arrangements. The analysis reveals that mean overtopping discharges for simple sloping structures in an almost deep water environment could be robustly estimated for dynamic water level changes by means of the present design formulae. In contrast, the role of dynamic changes of the wave steepness led to a substantial discrepancy of overtopping volumes by a factor of two. This finding opens new discussion on methodology and criteria design of coastal protection infrastructure under dynamic exposure to storm surges and in lieu of alterations stemming from projected sea level rise.

AB - The wave overtopping discharge at coastal defense structures is directly linked to the freeboard height. By means of physical modelling, experiments on wave overtopping volumes at sloped coastal structures are customarily determined for constant water levels and static wave steepness conditions (e.g., specific wave spectrum). These experiments are the basis for the formulation of empirically derived and widely acknowledged wave overtopping estimations for practical design purposes. By analysis and laboratory reproduction of typical features from exemplarily regarded real storm surge time series in German coastal waters, the role of non-stationary water level and wave steepness were analyzed and adjusted in experiments. The robustness of wave overtopping estimation formulae (i.e., the capabilities and limitations of such a static projection of dynamic boundary conditions) are outlined. Therefore, the classic static approach is contrasted with data stemming from tests in which both water level and wave steepness were dynamically altered in representative arrangements. The analysis reveals that mean overtopping discharges for simple sloping structures in an almost deep water environment could be robustly estimated for dynamic water level changes by means of the present design formulae. In contrast, the role of dynamic changes of the wave steepness led to a substantial discrepancy of overtopping volumes by a factor of two. This finding opens new discussion on methodology and criteria design of coastal protection infrastructure under dynamic exposure to storm surges and in lieu of alterations stemming from projected sea level rise.

KW - Coastal structures

KW - Dynamic exposure

KW - Physical model test

KW - Storm surge

KW - Tide

KW - Water level variations

KW - Wave flume

KW - Wave overtopping

UR - http://www.scopus.com/inward/record.url?scp=85084080076&partnerID=8YFLogxK

U2 - 10.3390/JMSE8020063

DO - 10.3390/JMSE8020063

M3 - Article

AN - SCOPUS:85084080076

VL - 8

JO - Journal of Marine Science and Engineering

JF - Journal of Marine Science and Engineering

IS - 2

M1 - 63

ER -