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Hydrological Connectivity in Vegetated River Deltas: The Importance of Patchiness Below a Threshold
Author(s) -
Wright Kyle,
Hiatt Matthew,
Passalacqua Paola
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl079183
Subject(s) - delta , vegetation (pathology) , hydrology (agriculture) , environmental science , sediment transport , biogeochemical cycle , geology , river delta , percolation (cognitive psychology) , sediment , hydraulics , residence time (fluid dynamics) , geomorphology , ecology , medicine , geotechnical engineering , pathology , neuroscience , engineering , biology , aerospace engineering
Hydrological connectivity in coastal deltas is important for delivering flow, sediment, and nutrients to the island interiors. The roughness of island vegetation limits connectivity, but how important is the spatial distribution of vegetation? Using hydrodynamic modeling, we test the influence of vegetated percent cover, patch size, and stem density on the discharge‐fraction allocated to the islands of an idealized delta complex, modeled after Wax Lake Delta. We find that heterogeneity has negligible effects when vegetation is relatively sparse but is important when vegetation is relatively dense and covers less than a “disconnectivity” threshold of 40–50% of the islands, near the theoretical percolation limit. Below this threshold, preferential flow paths develop in the islands, which alter the hydraulics and residence time distribution of the delta complex and enhance potential sediment transport with respect to model runs with uniform vegetation. Patchiness has hydrogeomorphic and biogeochemical implications, which should be considered when modeling deltaic systems.