Water Institute of the Gulf

Adaptation pathways are responsive planning tools intended to help decision-makers incorporate uncertainty of a future scenario while optimizing the use of their resources. In this project, an adaptation pathway was generated for a developed barrier island community, Dauphin Island, Alabama, USA. The project period was October 2019 to April 2022, with community engagement beginning in January 2020. Initial meetings were held with the community to identify vulnerable locations and co-develop adaptation strategies that were evaluated throughout the project. The effectiveness of adaptation strategies to reduce damage was estimated with a process-based numerical model, XBeach, which simulated inundation and morphological change due to Hurricane Nate (2017) and several sea-level rise scenarios. Depending on the Dauphin Island priority area, “damage” was defined as saltwater contamination in a freshwater lake, sand deposits on Dauphin Island’s main through route, or decreased sediment volume. When damage was sustained for a given strategy and sea-level rise scenario, a “tipping point” was reached and triggered the implementation of another strategy. Adaptation pathways were generated for two focus locations, with one location having two tipping points resulting in two pathways. This project revealed adaptation pathways are dependent on definitions of tipping points and location even within the same community. Community engagement revealed vulnerable locations that were previously unrealized and identified ‘reasonable’ or ‘unreasonable’ adaptation strategies based on community needs and desires. While the pathways produced for Dauphin Island are likely not transferrable to other locations, both findings are key to effective application of the adaptation pathways approach and generating a pathway accepted by the community.

Abstract Quantifying watershed process variability consistently with climate change and ecohydrological dynamics remains a central challenge in hydrology. Stochastic ecohydrology characterizes hydrologic variability through probability distributions that link climate, hydrology, and ecology. However, these approaches are often limited to small spatial scales (e.g., point or plot level) or focus on specific fluxes (e.g., streamflow), without accounting for the entire water balance at the basin scale. While semi‐distributed models account for spatial heterogeneity and upscaled hydrologic fluxes, they lack the analytical simplicity of stochastic ecohydrology or the SCS‐CN method and, perhaps more importantly, do not directly characterize probability distributions that integrate the effects of past random variability in hydroclimatic conditions. This hinders an efficient characterization of hydrological statistics at the watershed scale. To overcome these limitations, we merge stochastic ecohydrology, the spatial upscaling of semi‐distributed modeling, and the SCS‐CN rainfall‐runoff partitioning. The resulting unified model analytically characterizes watershed ecohydrological and hydrological statistics using probability density functions (PDFs) that are functions of climate and watershed model parameters (e.g., baseflow coefficient)—something unattainable with the Monte Carlo methods of traditional stochastic hydrology. Calibrated across 81 watersheds in Florida and southern Louisiana, the model PDFs precisely capture the long‐term average water balance and runoff variance, as well as the runoff quantiles with a median Nash–Sutcliffe efficiency of 0.98. These results also advance the SCS‐CN method by providing an analytical PDF for the Curve Number (CN), explicitly linked to climate variables, baseflow, and the long‐term water balance partitioning described by the Budyko curve.

Abstract Access to critical and essential services (CES) is vital for community resilience, particularly in coastal areas facing natural hazards. We developed a novel transportation network analysis framework to assess access fragility (in terms of losing access), criticality (in terms of the importance of CES facilities), and equity of CES access across five Louisiana communities. We used drive time to the closest facility, marginal drive time to the second closest facility, and the number of alternatives within critical time thresholds as three measures for fragility analysis. Our findings show that fragility is not limited to rural areas—urban communities experiencing in-migration also face risks due to limited alternatives. Removing one facility at a time revealed that it can cause up to a 500% increase in drive times to dialysis centers and hospitals for residents of Morgan City and Stephensville, while, on average, removing one random high school results in a 6%–30% increase in drive time across communities. We also introduced a criticality ranking method using total population, percentage of the population without an alternative, and marginal drive time for populations without alternatives, and calculated rank stability across different weightings of these three measures to identify facilities that are consistently most critical. Cameron Parish had the highest concentration of critical facilities, though facilities in Slidell and Mandeville also ranked highly, highlighting potential capacity concerns for two communities with growing populations. Finally, our equity analysis, performed using Monte Carlo simulations, shows that Native populations are disproportionately affected by limited access to services (∼29% are identified as outliers for dialysis and hospital access), while White populations experience the lowest average drive times to most CES facilities.

Abstract From the Summit of South American–Arab Countries (ASPA) created in 2005, UAE–South American relations have continued to develop based on a combination of pragmatism, threat perception, political support and expanding economic interests. We argue that the strength of UAE engagement in this region is consistent with its attempts to build, deploy and benefit from soft power globally through economic statecraft in a mutually reinforcing series of bilateral and multilateral relationships. These include forums such as the Southern Common Market (MERCOSUR) and the expanding BRICS grouping (Brazil, Russia, India, China and South Africa). The article draws on primary and secondary data in English, Portuguese and Spanish, focusing mainly on UAE relations with Brazil and Venezuela. We find that through a myriad of growing investment relations and first‐mover advantage on arms and industrial cooperation, the UAE is well positioned vis‐à‐vis other Gulf Cooperation Council (GCC) states to benefit from the economic, diplomatic and security ties that could boost its relational autonomy in a competitive and uncertain regional and international environment.

Many Mississippi River Delta studies have shown recent declines in fluvial sediment load from the river and associated land loss. In contrast, recent sedimentary processes on the subaqueous delta are less documented. To help address this knowledge gap, multicores were collected offshore from the three main river outlets at water depths of 25–280 m in June 2017 just after the peak river discharge period, with locations selected based on 2017 U.S. Geological Survey seabed mapping. The coring locations included the undisturbed upper foreset, mudflow lobes, gullies, and the undisturbed prodelta. Nine multicores were analyzed for Beryllium-7 activity, and four cores were analyzed for excess Thorium-234 activity via gamma spectrometry, granulometry and X-radiography. Our results indicate a general trend of declining 7Be and 234Th activities and inventories with increasing distance from sources and in deeper water. The core X-radiographs are graded from the predominantly physically stratified nearshore to the more bioturbated offshore, consistent with the sedimentation patterns. Sediment focusing assessed via the 7Be and 234Th sediment inventories shows preferential sedimentation in gully and lobe environments, whereas the upper foreset and prodelta focusing factors are relatively depleted. Overall, short-term sediment deposition from the main fluvial source remains active offshore from all three major river outlets, despite the overall declining river load.

Coastal restoration projects often require sediment resources borrowed from estuarine or marine ecosystems. A generalized additive modeling (GAM) framework was used to characterize fish-habitat relationships and predict spatiotemporal and ontogenetic shifts of Gulf sturgeon distribution within an impacted estuary in the northern Gulf of Mexico, Lake Pontchartrain. Habitat use and movement of Gulf sturgeon (n = 103) was monitored using an array of acoustic receivers (n = 81) from 2016 to 2019. Telemetry data was paired with environmental conditions hindcast from a high-resolution hydrodynamic model to develop GAMs for three life stages of Gulf sturgeon: juvenile, sub-adult, and adult. Model results demonstrated clear spatial, temporal, and ontogenetic shifts in habitat use for Gulf sturgeon in the Lake Pontchartrain estuary. The importance of spatial and temporal variables in the final models of all life stages suggests that distribution of Gulf sturgeon within the estuary is more likely driven by biology (prey distribution) rather than environment. Interestingly, dependence of Gulf sturgeon on the estuary for overwintering habitat declined with ontogeny. The northeastern shoreline of Lake Pontchartrain was identified as potential nursery habitat for overwintering juvenile sturgeon from the Pearl River, while eastern portions of the estuary and associated channels provide critical staging habitat and corridors of connectivity for migrating sub-adult and adult sturgeon. Given the clear need to prioritize conservation of Gulf sturgeon while restoring coastal marshes, findings from this study provide needed information to shape future coastal restoration and inform the siting and timing of future dredging operations in Lake Pontchartrain.

Tidal-inlet systems are dynamic features that respond to short-term (e.g., storms) and longer-term processes (e.g., sea-level rise, changes in tidal prism). The Chincoteague Inlet system, located along the northern Eastern Shore of Virginia (USA), is a dynamic coastal complex that experiences rapid change associated with sediment redistribution and a shifting inlet throat due to the southern elongation of adjacent Assateague Island. In this study, a numerical model based on Delft3D with coupled flow–waves, multiclass sediment transport, and morphologic feedback was developed to quantify the hydrodynamic and geomorphic controls within this rapidly evolving inlet–spit system and to develop a more comprehensive understanding of regional to local controls on sediment-transport pathways. Model results show that most of the sand transport along southern Assateague Island is sequestered nearshore and proximally in deeper sinks within Fishing Point, and, of that, only finer sand sizes are transported around the spit, confirming previous analysis and hypothesis. The model also showed that sand transport toward the south increases along Wallops Island and quantified spatially explicit transport trends for selected sediment classes, revealing that coarser sediment bypassing is a punctuated process that is proportional to storms.