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Modeling the effects of vegetation distribution and density on hydrological connectivity and water age in a river delta
  • Matthew Hiatt,
  • Madoche Jean Louis
Matthew Hiatt
Louisiana State University Department of Oceanography and Coastal Sciences

Corresponding Author:[email protected]

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Madoche Jean Louis
Louisiana State University Department of Oceanography and Coastal Sciences
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Abstract

Water transport timescales (WTTs) quantify how long it takes for water to travel through or remain in a system and are often cast as indicators of ecosystem function and health. Such timescales are known to be affected by vegetation in various environments. We quantify the impact of floodplain vegetation on WTTs within the Wax Lake Delta (WLD), a river delta system in Louisiana, USA, using a high-resolution Delft3D Flexible Mesh (DFM) model incorporating vegetation-induced flow resistance. We show that increased vegetation density leads to extended WTTs within vegetated sections of WLD while fostering flow localization and accelerating transport within distributary channels. We find that the presence or absence of floodplain vegetation significantly influences the volumetric flow directed toward the floodplain, with spatial distribution exerting more control than vegetation density. Vegetation density and spatial arrangement have minimal impact on flow directed out of the deltaic floodplain, indicating that vegetation does not constrain flow across the bayward boundary. Floodplain vegetation strongly influences local-scale transport timescales within the deltaic floodplain but minimally affects water age distributions within distributary channels. Furthermore, network-scale water age distribution remains largely unaffected by vegetation density and spatial arrangement, except for slight modifications in the heavy right tail of the distribution. These findings contribute to a better understanding of how vegetation affects deltaic hydrology across scales, highlighting the importance of considering multi-scale vegetation influences for coastal restoration and management strategies.
01 Mar 2024Submitted to Ecohydrology
01 Mar 2024Assigned to Editor
01 Mar 2024Submission Checks Completed
05 Mar 2024Review(s) Completed, Editorial Evaluation Pending
24 Mar 2024Reviewer(s) Assigned