The economic program of the co-operative commonwealth federation

Thesis (M.A.)--Boston University, 1947. This item was digitized by the Internet Archive

New River Inlet DRI: Observations and Modeling of Flow and Material Exchange

LONG-TERM GOALS: The goal of our effort is to understand river and inlet fluid dynamics through in situ field observations and model validation.N0001411WX20962; N0001412WX20498; N000141010409, N00014101037

New River Inlet DRI: Observations and Modeling of Flow and Material Exchange & Field and Numerical Study of the Columbia River Mouth

LONG-TERM GOALS: The goal of our effort is to understand river and inlet fluid dynamics through in situ field observations and model validation.N0001411WX20962; N0001412WX20498; N0001413WX20480; N000141110376, N000141010379, N00014131018

Nearshore response to cold air outbreaks in the Gulf of Mexico

These data in this paper are available through the GRIIDC website: data. gulfresearchinitiative.org.The article of record as published may be found at https://doi.org/10.1016/j.ecss.2020.106604This research paper was made possible by the BP and The Gulf of Mexico Research Initiative.This research paper was made possible by the BP and The Gulf of Mexico Research Initiative

Responses of Swimmers Caught in Rip Currents: Perspectives on Mitigating the Global Rip Current Hazard

Rip currents are the primary mechanism on many of the world’s beaches associated with rescues and drownings and have long been the focus of beachgoer education and awareness strategies. Traditional approaches to mitigating the rip current hazard typically provide information on escape procedures for beachgoers caught in a rip current. Several of these approaches are now being challenged by new scientific findings leading to uncertainty and debate amongst scientists and beach safety practitioners. This paper suggests that future research efforts on mitigating the rip current hazard should focus on quantifying the physical and behavioral responses of beachgoers who have been caught in rip currents. Descriptions of new approaches adopted recently in Australia by a joint collaboration between the University of New South Wales and Surf Life Saving Australia are presented

Corrigendum to “Nearshore response to cold air outbreaks in the Gulf of Mexico” [Estuar. Coast Shelf Sci. 235 (5 April 2020) 106604]

Corrects a missing DOI in the data attribution statement.17 USC 105 interim-entered record; under review

Riverine Flow Observations and Modeling- Sensitivity of Delft3D River Model to Bathymetric Variability

Long-term goals: The goal of our effort is to understand river and inlet fluid dynamics through in situ field observations and model validation.NPS Award Number: (N0001410WX21049; N0001411WX20962)UM Award Number: (N000141010379

Riverine Flow Observations and Modeling- Sensitivity of Delft3D River Model to Bathymetric Variability

Long-term goals: The goal of our effort is to understand river and inlet fluid dynamics through in situ field observations and model validation.NPS Award Number: (N0001410WX21049; N0001411WX20962)UM Award Number: (N000141010379

Dynamics of rip currents associated with groynes - field measurements, modelling and implications for beach safety

Rip currents can occur around groynes and other coastal structures (e.g. breakwaters and geological headlands), which provide a boundary to the wave-induced flow field and present a hazard to water users worldwide. Shore-normal groynes are common along drift-aligned coasts. In northern Europe these are often low-energy, fetch-limited environments that are dominated by locally generated wind waves. The presence of boundary-controlled rip currents due to groynes is supported anecdotally in literature, but few field measurements of their presence and dynamics exist. This study provides new quantitative scientific understanding of the dynamics of boundary-controlled rip currents within this setting. A 10-day field experiment at Boscombe beach on the south coast of England measured rip currents and nearshore hydrodynamics around an impermeable groyne field. Observations from both fixed instruments (wave, tide and current metres) and GPS-drifters confirmed the presence and characteristics of hazardous topographic rip currents around a groyne structure during a number of oblique wave events and drift reversals. The strongest offshore-directed rip velocities of up to 1ms-1 (10-min average) and 2ms-1 (instantaneous) were measured on the updrift side of the groyne where the longshore current generated within the embayment was deflected offshore. These strong rip flows were measured under relatively small wave heights (Hs<1m) and presented a significant bathing hazard. A calibrated and validated numerical model (XBeach) was used, in support of measured data, to explore the key environmental controls on rip behaviour across a range of groyne configurations and wave conditions not observed in the field. Key outcomes were that: 1) upstream deflected rip flows were found to be strongly correlated to the alongshore thrust due to wave forcing; 2) the groyne length relative to surf zone width strongly controlled the offshore extent of rip flows, with a significant increase in surf zone exits above a relative groyne length (length/surf width) of 1.25; and 3) rip flows increase up to a relative groyne spacing (spacing/length) of around 4-6, above which alongshore currents are fully developed. These findings have been distilled into some key principals that are relevant to the assessment of boundary-controlled rip hazard on beaches

Temporal Patterns of Diversification across Global Cichlid Biodiversity (Acanthomorpha: Cichlidae)

The contrasting distribution of species diversity across the major lineages of cichlids makes them an ideal group for investigating macroevolutionary processes. In this study, we investigate whether different rates of diversification may explain the disparity in species richness across cichlid lineages globally. We present the most taxonomically robust time-calibrated hypothesis of cichlid evolutionary relationships to date. We then utilize this temporal framework to investigate whether both species-rich and depauperate lineages are associated with rapid shifts in diversification rates and if exceptional species richness can be explained by clade age alone. A single significant rapid rate shift increase is detected within the evolutionary history of the African subfamily Pseudocrenilabrinae, which includes the haplochromins of the East African Great Lakes. Several lineages from the subfamilies Pseudocrenilabrinae (Australotilapiini, Oreochromini) and Cichlinae (Heroini) exhibit exceptional species richness given their clade age, a net rate of diversification, and relative rates of extinction, indicating that clade age alone is not a sufficient explanation for their increased diversity. Our results indicate that the Neotropical Cichlinae includes lineages that have not experienced a significant rapid burst in diversification when compared to certain African lineages (rift lake). Neotropical cichlids have remained comparatively understudied with regard to macroevolutionary patterns relative to African lineages, and our results indicate that of Neotropical lineages, the tribe Heroini may have an elevated rate of diversification in contrast to other Neotropical cichlids. These findings provide insight into our understanding of the diversification patterns across taxonomically disparate lineages in this diverse clade of freshwater fishes and one of the most species-rich families of vertebrates.This work was supported by NSF grants DEB 0716155, DEB 0732642, and DEB 1060869 to WLS, DEB 0910081 to MPD, DEB 0916695 to PC, DEB 1258141 to MPD and WLS, DEB 1311408 to CDM, and IOS 0749943 to JSS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript