Now showing 1 - 6 of 6
  • Publication
    River Delta Morphotypes Emerge From Multiscale Characterization of Shorelines
    (2023)
    L. Vulis
    ;
    ;
    H. Ma
    ;
    J. H. Nienhuis
    ;
    C. M. Broaddus
    ;
    J. Brown
    ;
    D. A. Edmonds
    ;
    J. C. Rowland
    ;
    E. Foufoula‐Georgiou
    Delta shoreline structure has long been hypothesized to encode information on the relative influence of fluvial, wave, and tidal processes on delta formation and evolution. We introduce here a novel multiscale characterization of shorelines by defining three process-informed morphological metrics. We show that this characterization yields self-emerging classes of morphologically similar deltas, that is, delta morphotypes, and also predicts the dominant forcing of each morphotype. Then we show that the dominant forcings inferred from shoreline structure generally align with those estimated via relative sediment fluxes, while positing that misalignments arise from spatiotemporal heterogeneity in deltaic sediment fluxes not captured in their estimates. The proposed framework for shoreline characterization advances our quantitative understanding of how shoreline features reflect delta forcings, and may aid in deciphering paleoclimate from images of ancient deposits and projecting delta morphologic response to changes in sediment fluxes.
      5
  • Publication
    The Entropic Braiding Index : A Robust Metric to Account for the Diversity of Channel Scales in Multi‐Thread Rivers
    (2022) ;
    Jon Schwenk
    ;
    Maarten Kleinhans
    ;
    Ajay B. Limaye
    ;
    Lawrence Vulis
    ;
    Paul Carling
    ;
    Holger Kantz
    ;
    Efi Foufoula‐Georgiou
    The Braiding Index (BI), defined as the average count of intercepted channels per cross-section, is a widely used metric for characterizing multi-thread river systems. However, it does not account for the diversity of channels (e.g., in terms of water discharge) within different cross-sections, omitting important information related to system complexity. Here we present a modification of BI, the Entropic Braiding Index (eBI), which augments the information content in BI by using Shannon Entropy to encode the diversity of channels in each cross section. eBI is interpreted as the number of “effective channels” per cross-section, allowing a direct comparison with the traditional BI. We demonstrate the potential of the ratio BI/eBI to quantify channel disparity, differentiate types of multi-thread systems (braided vs. anastomosed), and assess the effect of discharge variability, such as seasonal flooding, on river cross-section stability
      39  8
  • Publication
    Dynamic Clusters to Infer Topologic Controls on Environmental Transport of River Networks
    (2022) ;
    Roy, Juthika
    ;
    Singh, Arvind
    The knowledge of structural controls of river networks (RNs) on transport dynamics is important for modeling and predicting environmental fluxes. To investigate impacts of RN’s topology on transport processes, we introduce a systematic framework based on the concept of dynamic clusters, where the connectivity of subcatchments is assessed according to two complementary criteria: minimum- and maximum-flow connectivity. Our analysis from simple synthetic RNs and several natural river basins across the United States reveals the key topological features underlying the efficiency of flux transport and aggregation. Namely, the timing of basin-scale connectivity at low-flow conditions is controlled by the abundance of topologically asymmetric junctions (side-branching), which at the same time, result in a slow-down of the flux convergence at the outlet (maximum-flow). Our results, when compared with observed topological trends in RNs as a function of climate, indicate that humid basins exhibit topologies which are “naturally engineered” to slow-down fluxes.
      60  16
  • Publication
    First‐Order River Delta Morphology Is Explained by the Sediment Flux Balance From Rivers, Waves, and Tides
    (2022) ;
    Broaddus, C. M
    ;
    Vulis, L. M
    ;
    Nienhuis, J. H
    ;
    Brown, J
    ;
    Foufoula‐Georgiou, E
    ;
    Edmonds, D. A
    We present a novel quantitative test of a 50-year-old hypothesis which asserts that river delta morphology is determined by the balance between river and marine influence. We define three metrics to capture the first-order morphology of deltas (shoreline roughness, number of distributary channel mouths, and presence/absence of spits), and use a recently developed sediment flux framework to quantify the river-marine influence. Through analysis of simulated and field deltas we quantitatively demonstrate the relationship between sediment flux balance and delta morphology and show that the flux balance accounts for at least 35% of the variance in the number of distributary channel mouths and 42% of the variance in the shoreline roughness for real-world and simulated deltas. We identify a tipping point in the flux balance where wave influence halts distributary channel formation and show how this explains morphological transitions in real world deltas.
      15  1
  • Publication
    Climate Signatures on Lake And Wetland Size Distributions in Arctic Deltas
    (2021) ;
    Vulis, Lawrence
    ;
    Zaliapin, Ilya
    ;
    Rowland, Joel C.
    ;
    Foufoula-Georgiou, Efi
    Lake areas in arctic deltas exhibit a lognormal distribution associated with a simple mechanistic growth process. 2. Wetland areas exhibit a power law distribution consistent with inundated topography. 3. Colder arctic deltas have larger average lake sizes, likely due to thicker permafrost restricting sub-lake hydrologic connectivity.
    Scopus© Citations 1  32  18
  • Publication
    Channel Network Control on Seasonal Lake Area Dynamics in Arctic Deltas
    (2020) ;
    Foufoula-Georgiou, Efi
    ;
    Piliouras, Anastasia
    ;
    Rowland, Joel
    ;
    Schwenk, Jon
    ;
    Vulis, Lawrence
    The abundant lakes dotting arctic deltas are hotspots of methane emissions and biogeochemical activity, but seasonal variability in lake extents introduces uncertainty in estimates of lacustrine carbon emissions, typically performed at annual or longer time scales. To characterize variability in lake extents, we analyzed summertime lake area loss (i.e., shrinkage) on two deltas over the past 20 years, using Landsat-derived water masks. We find that monthly shrinkage rates have a pronounced structured variability around the channel network with the shrinkage rate systematically decreasing farther away from the channels. This pattern of shrinkage is predominantly attributed to a deeper active layer enhancing near-surface connectivity and storage and greater vegetation density closer to the channels leading to increased evapotranspiration rates. This shrinkage signal, easily extracted from remote sensing observations, may offer the means to constrain estimates of lacustrine methane emissions and to develop process-based estimates of depth to permafrost on arctic deltas.
    Scopus© Citations 2  639  63