An Analytical Solution for Watershed Delineation in a Marsh Platform Drained by Tidal Creeks

Abstract Coastal marshes are important ecosystems providing numerous ecological services, including coastal protection, carbon storage, and biodiversity enhancement. Salt marshes are dissected by dendritic creeks dividing the marsh into distinct watersheds. The size and location of watersheds influe...

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Main Authors: Chia‐Chu Chu, Alberto Canestrelli, Daniele Pinton, Sergio Fagherazzi
Format: Article
Language:English
Published: Wiley 2025-03-01
Series:Water Resources Research
Subjects:
Online Access:https://doi.org/10.1029/2024WR038111
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author Chia‐Chu Chu
Alberto Canestrelli
Daniele Pinton
Sergio Fagherazzi
author_facet Chia‐Chu Chu
Alberto Canestrelli
Daniele Pinton
Sergio Fagherazzi
author_sort Chia‐Chu Chu
collection DOAJ
description Abstract Coastal marshes are important ecosystems providing numerous ecological services, including coastal protection, carbon storage, and biodiversity enhancement. Salt marshes are dissected by dendritic creeks dividing the marsh into distinct watersheds. The size and location of watersheds influence marsh hydrodynamics, which in turn, affect sediment and nutrient transport. Consequently, these processes shape marsh morphology and ecology. Current methods for determining divide positions rely exclusively on numerical approaches, which are computationally intensive, and do not explain how variations in marsh and creek geometry, friction, mean sea level, and tide influence the location of these divides. In this study, we introduce a simplified analytical model based on the shallow water equations (SWEs) to rapidly locate watershed divides in salt marshes with parallel creeks. We compare the analytical results with those obtained numerically using a two‐dimensional Poisson model, a linearized form of the SWEs, alongside a two‐dimensional Delft3D model, which solves the full SWEs. The proposed explicit analytical solution well agrees with numerical predictions. Our results indicate the divide moves toward the centerline of the marsh platform (i.e., the position equidistant from two neighboring creeks) as marsh friction, tidal amplitude, creek depth, marsh width, and MSL increase. Conversely, the divide moves away from the centerline for larger creek friction, water depth on the marsh platform, creek length, creek width, and larger difference in the geometry of the creeks. Our method enables to estimate the effect of man‐made and natural modifications of marsh systems on watershed shape, and, consequently, on the water and sediment fluxes.
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spelling doaj-art-be076f49a08641c4a8cb854e1bb07c652025-08-20T03:30:56ZengWileyWater Resources Research0043-13971944-79732025-03-01613n/an/a10.1029/2024WR038111An Analytical Solution for Watershed Delineation in a Marsh Platform Drained by Tidal CreeksChia‐Chu Chu0Alberto Canestrelli1Daniele Pinton2Sergio Fagherazzi3Department of Civil and Coastal Engineering University of Florida Gainesville FL USADepartment of Civil and Coastal Engineering University of Florida Gainesville FL USADepartment of Civil and Coastal Engineering University of Florida Gainesville FL USADepartment of Earth and Environment Boston University Boston MA USAAbstract Coastal marshes are important ecosystems providing numerous ecological services, including coastal protection, carbon storage, and biodiversity enhancement. Salt marshes are dissected by dendritic creeks dividing the marsh into distinct watersheds. The size and location of watersheds influence marsh hydrodynamics, which in turn, affect sediment and nutrient transport. Consequently, these processes shape marsh morphology and ecology. Current methods for determining divide positions rely exclusively on numerical approaches, which are computationally intensive, and do not explain how variations in marsh and creek geometry, friction, mean sea level, and tide influence the location of these divides. In this study, we introduce a simplified analytical model based on the shallow water equations (SWEs) to rapidly locate watershed divides in salt marshes with parallel creeks. We compare the analytical results with those obtained numerically using a two‐dimensional Poisson model, a linearized form of the SWEs, alongside a two‐dimensional Delft3D model, which solves the full SWEs. The proposed explicit analytical solution well agrees with numerical predictions. Our results indicate the divide moves toward the centerline of the marsh platform (i.e., the position equidistant from two neighboring creeks) as marsh friction, tidal amplitude, creek depth, marsh width, and MSL increase. Conversely, the divide moves away from the centerline for larger creek friction, water depth on the marsh platform, creek length, creek width, and larger difference in the geometry of the creeks. Our method enables to estimate the effect of man‐made and natural modifications of marsh systems on watershed shape, and, consequently, on the water and sediment fluxes.https://doi.org/10.1029/2024WR038111marshescreekswatershed divideanalytical solutionPoissonDelft3D
spellingShingle Chia‐Chu Chu
Alberto Canestrelli
Daniele Pinton
Sergio Fagherazzi
An Analytical Solution for Watershed Delineation in a Marsh Platform Drained by Tidal Creeks
Water Resources Research
marshes
creeks
watershed divide
analytical solution
Poisson
Delft3D
title An Analytical Solution for Watershed Delineation in a Marsh Platform Drained by Tidal Creeks
title_full An Analytical Solution for Watershed Delineation in a Marsh Platform Drained by Tidal Creeks
title_fullStr An Analytical Solution for Watershed Delineation in a Marsh Platform Drained by Tidal Creeks
title_full_unstemmed An Analytical Solution for Watershed Delineation in a Marsh Platform Drained by Tidal Creeks
title_short An Analytical Solution for Watershed Delineation in a Marsh Platform Drained by Tidal Creeks
title_sort analytical solution for watershed delineation in a marsh platform drained by tidal creeks
topic marshes
creeks
watershed divide
analytical solution
Poisson
Delft3D
url https://doi.org/10.1029/2024WR038111
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