What Controls the Transition from Confined to Unconfined Flow?                    Analysis of Hydraulics in a Coastal River Delta

Hiatt, Matthew; Passalacqua, Paola

doi:10.1061/(asce)hy.1943-7900.0001309

Cited by 35 publications

(77 citation statements)

References 56 publications

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“…Emergent vegetation has been shown to affect flow at the plant and patch scale, with implications for wetland growth and channel erosion [ Jadhav and Buchberger , ; Luhar et al ., ; Vandenbruwaene et al ., ]. Our results agree with the findings of Hiatt and Passalacqua [], who show that channel‐island hydrological connectivity decreases as island roughness increases.…”

Section: Discussionsupporting

confidence: 92%

“…The upstream to downstream orientation of the discharge information transfer suggests a possible similarity among the time scales of information transfer and the physical travel times of water in the delta. We compare the information transfer time scales to the water transport travel times obtained from hydrodynamic modeling at WLD based on the solution of the 2‐D shallow water equations [ Hiatt and Passalacqua , ]. After computing the travel times through channels and islands from the velocities at every cell in the domain (Figure and Table ), we find that the modeled travel times are within the estimated range of information flow time scales at all locations, with the exception of Greg Island and Pintail Island.…”

Section: Discussionmentioning

confidence: 81%

“…Its strength is higher after tidal fluctuations are removed (Figure e) and lower after the longer‐term fluctuations are removed (Figure f). Spatial differences in the water level response to discharge occur with an upstream to downstream pattern as flow down‐delta becomes increasingly unconfined [ Hiatt and Passalacqua , ], resulting in a more attenuated discharge signal, hence lower synchronization. In such a small system as WLD, however, these differences are subtle, but could be more pronounced in a large and heterogeneous system.…”

Section: Discussionmentioning

confidence: 99%

“…The domain is only partially shown as it extends 100 km upstream. For more information on the model, see Hiatt and Passalacqua [].…”

Section: Discussionmentioning

confidence: 99%

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Process connectivity in a naturally prograding river delta

Sendrowski

Passalacqua

2017

Water Resources Research

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River deltas are lowland systems that can display high hydrological connectivity. This connectivity can be structural (morphological connections), functional (control of fluxes), and process connectivity (information flow from system drivers to sinks). In this work, we quantify hydrological process connectivity in Wax Lake Delta, coastal Louisiana, by analyzing couplings among external drivers (discharge, tides, and wind) and water levels recorded at five islands and one channel over summer 2014. We quantify process connections with information theory, a branch of mathematics concerned with the communication of information. We represent process connections as a network; variables serve as network nodes and couplings as network links describing the strength, direction, and time scale of information flow. Comparing process connections at long (105 days) and short (10 days) time scales, we show that tides exhibit daily synchronization with water level, with decreasing strength from downstream to upstream, and that tides transfer information as tides transition from spring to neap. Discharge synchronizes with water level and the time scale of its information transfer compares well to physical travel times through the system, computed with a hydrodynamic model. Information transfer and physical transport show similar spatial patterns, although information transfer time scales are larger than physical travel times. Wind events associated with water level setup lead to increased process connectivity with highly variable information transfer time scales. We discuss the information theory results in the context of the hydrologic behavior of the delta, the role of vegetation as a connector/disconnector on islands, and the applicability of process networks as tools for delta modeling results.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

“…The domain is only partially shown as it extends 100 km upstream. For more information on the model, see Hiatt and Passalacqua [].…”

Section: Discussionmentioning

confidence: 99%

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Process connectivity in a naturally prograding river delta

Sendrowski

Passalacqua

2017

Water Resources Research

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“…The SDR varies between 0 and 1, thus providing an integrated, non‐dimensional measure of the degree of connectivity of sediment sources and transport pathways within the catchment. Other studies that use output fluxes to infer upstream connectivity include Ali and Roy (), which measures stream discharge and infers connectivity of zones of high soil moisture, and recent work on deltaic systems which quantifies the hydrological connectivity of channels and interdistributary islands (Larsen et al ., ; Hiatt and Passalacqua, , ), and relates sediment output from delta distributary channels to upstream connectivity between geomorphic elements of the delta system (Liang et al ., ; Passalacqua, ).…”

Section: Measuring Connectivitymentioning

confidence: 99%

Connectivity as an emergent property of geomorphic systems

Wohl

Brierley

Cadol

et al. 2018

Earth Surf Processes Landf

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Connectivity describes the efficiency of material transfer between geomorphic system components such as hillslopes and rivers or longitudinal segments within a river network. Representations of geomorphic systems as networks should recognize that the compartments, links, and nodes exhibit connectivity at differing scales. The historical underpinnings of connectivity in geomorphology involve management of geomorphic systems and observations linking surface processes to landform dynamics. Current work in geomorphic connectivity emphasizes hydrological, sediment, or landscape connectivity. Signatures of connectivity can be detected using diverse indicators that vary from contemporary processes to stratigraphic records or a spatial metric such as sediment yield that encompasses geomorphic processes operating over diverse time and space scales. One approach to measuring connectivity is to determine the fundamental temporal and spatial scales for the phenomenon of interest and to make measurements at a sufficiently large multiple of the fundamental scales to capture reliably a representative sample. Another approach seeks to characterize how connectivity varies with scale, by applying the same metric over a wide range of scales or using statistical measures that characterize the frequency distributions of connectivity across scales. Identifying and measuring connectivity is useful in basic and applied geomorphic research and we explore the implications of connectivity for river management. Common themes and ideas that merit further research include; increased understanding of the importance of capturing landscape heterogeneity and connectivity patterns; the potential to use graph and network theory metrics in analyzing connectivity; the need to understand which metrics best represent the physical system and its connectivity pathways, and to apply these metrics to the validation of numerical models; and the need to recognize the importance of low levels of connectivity in some situations. We emphasize the value in evaluating boundaries between components of geomorphic systems as transition zones and examining the fluxes across them to understand landscape functioning. © 2018 John Wiley & Sons, Ltd.

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Channel‐Island Connectivity Affects Water Exposure Time Distributions in a Coastal River Delta

Hiatt

Castañeda‐Moya

Twilley

et al. 2018

Water Resources Research

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The exposure time is a water transport time scale defined as the cumulative amount of time a water parcel spends in the domain of interest regardless of the number of excursions from the domain. Transport time scales are often used to characterize the nutrient removal potential of aquatic systems, but exposure time distribution estimates are scarce for deltaic systems. Here we analyze the controls on exposure time distributions using a hydrodynamic model in two domains: the Wax Lake delta in Louisiana, USA, and an idealized channel‐island complex. In particular, we study the effects of river discharge, vegetation, network geometry, and tides and use a simple model for the fractional removal of nitrate. In both domains, we find that channel‐island hydrological connectivity significantly affects exposure time distributions and nitrate removal. The relative contributions of the island and channel portions of the delta to the overall exposure time distribution are controlled by island vegetation roughness and network geometry. Tides have a limited effect on the system's exposure time distribution but can introduce significant spatial variability in local exposure times. The median exposure time for the WLD model is 10 h under the conditions tested and water transport within the islands contributes to 37–50% of the network‐scale exposure time distribution and 52–73% of the modeled nitrate removal, indicating that islands may account for the majority of nitrate removal in river deltas.

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What Controls the Transition from Confined to Unconfined Flow? Analysis of Hydraulics in a Coastal River Delta

Cited by 35 publications

References 56 publications

Process connectivity in a naturally prograding river delta

Process connectivity in a naturally prograding river delta

Connectivity as an emergent property of geomorphic systems

Channel‐Island Connectivity Affects Water Exposure Time Distributions in a Coastal River Delta

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