Quantification of salt transports due to exchange flow and tidal flow in estuaries

Fuente: arXiv
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Auteurs principaux: Biemond, Bouke, de Swart, Huib E., Dijkstra, Henk A.
Format: Preprint
Publié: 2024
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author Biemond, Bouke
de Swart, Huib E.
Dijkstra, Henk A.
author_facet Biemond, Bouke
de Swart, Huib E.
Dijkstra, Henk A.
contents To understand mechanisms of salt intrusion in estuaries, we develop a semi-analytical model, that explicitly accounts for salt transport by both exchange flow and tidal flow. This model, after calibration, successfully hindcasts hydrodynamics and salinity dynamics in three estuaries that have strongly different characteristics. We find, from analyzing the model results for these three estuaries, that salt transport processes by exchange flow and tidal flow interact through the subtidal stratification. Transport by exchange flow creates stratification, thereby generating a phase shift of tidal salinity with respect to the tidal flow, which is important for the magnitude of the tidal salt transport. Conversely, the strength of tidal currents determines the vertical mixing that breaks down stratification. A new analytical formulation is presented for the component of the salt transport driven by the depth-averaged tidal flow. This salt transport is larger than the component associated with the vertical shear of the tidal current. Finally, a method that yields analytical equations that quantify the importance of different contributions to the salt transport using only primary information is developed using approximate solutions for the subtidal stratification. This method performs well for the estuaries considered.
format Preprint
id arxiv_https___arxiv_org_abs_2408_06378
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Quantification of salt transports due to exchange flow and tidal flow in estuaries
Biemond, Bouke
de Swart, Huib E.
Dijkstra, Henk A.
Atmospheric and Oceanic Physics
Fluid Dynamics
To understand mechanisms of salt intrusion in estuaries, we develop a semi-analytical model, that explicitly accounts for salt transport by both exchange flow and tidal flow. This model, after calibration, successfully hindcasts hydrodynamics and salinity dynamics in three estuaries that have strongly different characteristics. We find, from analyzing the model results for these three estuaries, that salt transport processes by exchange flow and tidal flow interact through the subtidal stratification. Transport by exchange flow creates stratification, thereby generating a phase shift of tidal salinity with respect to the tidal flow, which is important for the magnitude of the tidal salt transport. Conversely, the strength of tidal currents determines the vertical mixing that breaks down stratification. A new analytical formulation is presented for the component of the salt transport driven by the depth-averaged tidal flow. This salt transport is larger than the component associated with the vertical shear of the tidal current. Finally, a method that yields analytical equations that quantify the importance of different contributions to the salt transport using only primary information is developed using approximate solutions for the subtidal stratification. This method performs well for the estuaries considered.
title Quantification of salt transports due to exchange flow and tidal flow in estuaries
topic Atmospheric and Oceanic Physics
Fluid Dynamics
url https://arxiv.org/abs/2408.06378