University of Twente Student Theses


Identifying tidal divides, tidal subbasins and tidal prisms in an exploratory model of multi-inlet tidal systems

Bogers, L.C. (2019) Identifying tidal divides, tidal subbasins and tidal prisms in an exploratory model of multi-inlet tidal systems.

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Abstract:Multi-inlet tidal systems typically consist of several barrier islands, separated by tidal inlets that connect a back-barrier basin to a sea or ocean. Hydraulic tidal divides, forming the boundaries between tidal subbasins corresponding to the inlets, can be identified based on the flow patterns in the back-barrier basin. In this study, these tidal divides are identified in the exploratory model by Roos et al. (2013). Furthermore, the model results are compared to the empirical O’Brien-Jarrett Law, which relates tidal prisms to the cross-sectional area of inlets, and a sensitivity analysis is performed with respect to the ocean conditions. From this, a relation between the tidal subbasin area and the cross-sectional area of an inlet is derived. The model combines Escoffier’s stability concept for tidal inlets with a hydrodynamic model. The evolution and stability of each tidal inlet depends on the balance between waves, transporting sediment into the inlet, and tidal currents, transporting sediment out of the inlets. Two possible methods of identifying tidal divides in the model by Roos et al. (2013) are compared. It is concluded that a method based on identifying lines of minimum flow velocity amplitude in the basin gives accurate results and can be used to divide the back-barrier basin into tidal subbasins for each open inlet, whereas the results of a method based on large phase differences in alongshore flow velocity amplitude cannot be used to calculate these tidal subbasin areas directly. The tidal prism is defined as the water volume entering a tidal (sub)basin during a characteristic tidal cycle. It is approximated by multiplying the tidal range with the tidal (sub)basin area. The actual tidal prism resulting from the model is calculated by integrating the flow discharge through the inlet over half a tidal cycle. The result is a linear relationship between the tidal prism
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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