Salt Intrusion as a Function of Estuary Length in Periodically Weakly Stratified Estuaries

Wei, Xiaoyan, Williams, Megan E, Brown, Jennifer M, Thorne, Peter D and Amoudry, Laurent O ORCID: 0000-0002-6592-6790 (2022) Salt Intrusion as a Function of Estuary Length in Periodically Weakly Stratified Estuaries. GEOPHYSICAL RESEARCH LETTERS, 49 (15).

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Official URL: http://dx.doi.org/10.1029/2022gl099082

Abstract

<jats:title>Abstract</jats:title><jats:p>Estuarine salt intrusion greatly threatens freshwater supply in surrounding lands. Physical barriers, which reduce the estuary length (<jats:italic>L</jats:italic>), are widely constructed to control salt intrusion. Yet, the role of <jats:italic>L</jats:italic> in salt intrusion remains unknown. Using a process‐based, idealized, semi‐analytical three‐dimensional model, we systematically investigate for the first time this unknown for tide‐dominated, periodically weakly stratified estuaries. Results show decreasing <jats:italic>L</jats:italic> significantly reduces salinities for short estuaries (<jats:italic>L</jats:italic> < <jats:italic>L</jats:italic><jats:sub><jats:italic>w</jats:italic></jats:sub>/4, with <jats:italic>L</jats:italic><jats:sub><jats:italic>w</jats:italic></jats:sub> the dominant tidal wavelength), but not for long estuaries. Tidal pumping remains a key salt importer in most estuaries, regardless of <jats:italic>L</jats:italic>. However, substantial decreases in <jats:italic>L</jats:italic> relative to <jats:italic>L</jats:italic><jats:sub><jats:italic>w</jats:italic></jats:sub>/4 can change the dominant landward salt importer from tidal pumping to horizontal diffusion. The latter, together with gravitational circulation, weakens responses of salt intrusion to changes in tidal and river forcing in short estuaries. This study highlights the importance of considering <jats:italic>L</jats:italic> to understanding and mitigating salt intrusion.</jats:p>

Item Type:	Article
Uncontrolled Keywords:	salt intrusion, lateral shear dispersion, gravitational circulation, tidal pumping, estuary, fresh water supply
Divisions:	Faculty of Science and Engineering > School of Environmental Sciences
Depositing User:	Symplectic Admin
Date Deposited:	12 Sep 2022 13:29
Last Modified:	25 Aug 2023 23:36
DOI:	10.1029/2022GL099082
Open Access URL:	https://doi.org/10.1029/2022GL099082
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3164394