TY - JOUR
T1 - Field measurements and numerical modelling of wind-driven exchange flows in a tidal inlet system in the Dutch Wadden Sea
AU - van Weerdenburg, Roy
AU - Pearson, Stuart
AU - van Prooijen, Bram
AU - Laan, Stendert
AU - Elias, Edwin
AU - Tonnon, Pieter Koen
AU - Wang, Zheng Bing
PY - 2021
Y1 - 2021
N2 - Multiple tidal inlet systems like the Wadden Sea have long been considered as separated basins, bordered by so-called tidal divides. Recently, it was however shown that fluxes of water and sediment occur over the borders of these basins, especially during wind events. In this paper, the wind-driven fluxes over these borders and the residual flow of water through the main inlet are studied. The study is based on flow measurements at the tidal divides and in the main inlet of the Ameland Inlet system in the Dutch Wadden Sea and on numerical modelling. The measurements were carried out during 40 days in the fall of 2017, including both calm conditions and storm events. Numerical simulations of a full year have been used for upscaling results from the measurements to system scale exchange flows, and to unravel the effects of several mechanisms. The wind-driven variability in exchange flows between back-barrier basins at tidal divides was measured in the field and reproduced by the numerical model. Water level set up increases the water depth and thus the conveyance capacity at tidal divides, such that the exchange flows increase in magnitude. The flow conditions due to wind forcing are similar for both tidal divides of the Ameland Basin. The conveyance capacity and therefore the total volume exchange are however different. This leads to a residual compensation flow through the main inlet, which is directed outward (i.e., in the ebb direction) during winds from the prevailing southwestern wind direction. The net discharge through the main inlet is therefore a consequence of the residual flows over the tidal divides.
AB - Multiple tidal inlet systems like the Wadden Sea have long been considered as separated basins, bordered by so-called tidal divides. Recently, it was however shown that fluxes of water and sediment occur over the borders of these basins, especially during wind events. In this paper, the wind-driven fluxes over these borders and the residual flow of water through the main inlet are studied. The study is based on flow measurements at the tidal divides and in the main inlet of the Ameland Inlet system in the Dutch Wadden Sea and on numerical modelling. The measurements were carried out during 40 days in the fall of 2017, including both calm conditions and storm events. Numerical simulations of a full year have been used for upscaling results from the measurements to system scale exchange flows, and to unravel the effects of several mechanisms. The wind-driven variability in exchange flows between back-barrier basins at tidal divides was measured in the field and reproduced by the numerical model. Water level set up increases the water depth and thus the conveyance capacity at tidal divides, such that the exchange flows increase in magnitude. The flow conditions due to wind forcing are similar for both tidal divides of the Ameland Basin. The conveyance capacity and therefore the total volume exchange are however different. This leads to a residual compensation flow through the main inlet, which is directed outward (i.e., in the ebb direction) during winds from the prevailing southwestern wind direction. The net discharge through the main inlet is therefore a consequence of the residual flows over the tidal divides.
KW - Exchange flows
KW - Flow measurements
KW - Tidal divides
KW - Wadden sea
KW - Wind-generated currents
UR - http://www.scopus.com/inward/record.url?scp=85117700512&partnerID=8YFLogxK
U2 - 10.1016/j.ocecoaman.2021.105941
DO - 10.1016/j.ocecoaman.2021.105941
M3 - Article
AN - SCOPUS:85117700512
SN - 0964-5691
VL - 215
SP - 1
EP - 12
JO - Ocean and Coastal Management
JF - Ocean and Coastal Management
M1 - 105941
ER -