The Grounding of Floating Objects in a Marginal Sea

Beaches, especially at or above the high tide line, are often covered in debris. Anobvious approach to understanding the source of this debris elsewhere in the ocean is to use Lagrangian methods (observationally or in numerical simulations). However, the actual grounding of these floating objects, that is, the transition between freely floating near the coast and motionless on land, is poorly understood. Here, 800 groundings from a recent circulation project using expendable tracked drifters in the Salish Sea are statistically analyzed. Although the grounding process for individual drifters can be complex and highly variable, suitable analyses show that the complications of coastlines can be statistically summarized in meaningful ways. The velocity structure approaching the coastline suggests a quasi-steady “log-layer” associated with coastline friction. Although groundings are marginally more likely to occur at higher tides, there are many counterexamples and the preference is not overwhelming. The actual grounding process is then well modelled as a stationary process using a classical eddy-diffusivity formulation, and the eddy diffusivity that best matches observations is similar to that appearing in open waters away from the coast. A new parameter in this formulation is equivalent to a mean shoreward velocity for floating objects, which could vary with beach morphology and also (in theory) be measured offshore. Finally, it appears that currently used ad-hoc beaching parameterizations should be reasonably successful in qualitative terms, but are unlikely to be quantitatively accurate enough for predictions of grounding mass budgets and fluxes.

Analysis of Rare Plant Occurrence Data for Monitoring Prioritization

Efforts to conserve rare plant species can be limited by a lack of time and funding for monitoring. Understanding species occurrence and distribution patterns within existing protected habitat and throughout the entire species range can help stewards prioritize rare plant monitoring. We created a database of rare plant occurrences from public, private, and research sources to analyze the distribution of rare plant species throughout the existing protected area within the Nature Reserve of Orange County in California, USA. We analyzed species occurrence relative to the urban edge, roads, trails, and mean high tide line. We also determined the vegetation community with the highest number of rare plant species to help prioritize habitats for conservation and restoration. We found that some parts of protected areas have more rare plant species and we also found sampling biases on the location of occurrence data. We found that rare species occur close to roads and trails and the mean high tide line. Rare species were in all vegetation communities within the reserve, including degraded areas. Using patterns of distribution and considering the immediate threats to a rare species population can help land managers and stewards prioritize monitoring toward the most threatened species.

A Framework for Classifying and Assessing Sea Level Rise Risk

Population risk assessments of sea level rise are key to understanding the impacts of climate change on coastal communities and necessary for adaptation planning. Future sea level rise exposes coastal populations to a spectrum of risk, but assessments often define exposure narrowly, such as areas experiencing permanent inundation only. We reviewed the most common sea level rise exposure assessment methods and identified three widely used spatial definitions of physical exposure risk: mean higher high water, the 100-year floodplain, and the low-elevation coastal zone. Taken individually, each treat risk to sea level rise as binary (affected or not affected), resulting in narrow definitions, homogenizing risk and exposure across space and time. We present a framework that integrates and smooths these classifications under a single continuous metric. To do so, we advance a sophisticated spatiotemporal flood-modeling approach -- expected annual exposure -- based on a probabilistic spatial envelope that unifies spatial extents between the high-tide line and the 10,000-year floodplain. We show that the effects from sea level rise will impact far more people far sooner than previously thought. In particular, our results suggest that single, binary extent assessments either underestimate or overestimate the magnitude of the at-risk populations while also spatially homogenizing the impacts to sea level rise. Our advance on modeling annual exposure provides a more robust and holistic assessment of the populations most at-risk to flooding from sea level rise. This typology can be used to guide new research connecting risk of sea level rise to related adaptation policies and planning.

Estimating Annual Onshore Aeolian Sand Supply from the Intertidal Beach Using an Aggregated-Scale Transport Formula

In this paper, we explore an approach for annual-scale transport prediction from the intertidal beach, in which we aggregate the surface conditions of the intertidal beach, in particular moisture content and roughness, and use hourly monitoring data of wind speed and wind direction. For our case study area (Egmond Beach, The Netherlands), we include Argus video imagery in our analysis to assess the occurrence of aeolian sand transport. With the approach described to determine a characteristic moisture content value for aeolian transport, we obtained surface moisture values of 1.2% to 3.2% for wind average and wind gust respectively, implying that we need a quite dry beach. This indicates that the main area for aeolian transport corresponds to the upper part of the intertidal source, most likely the region between mean high tide line and spring high tide line.

Sea Oats, Uniola paniculata

Sea oats occur throughout Florida on beach dunes and beaches and on coastal areas west to Texas and north to Maryland. Sea oats are vital dune builders that accumulate sand and prevent erosion due to wind, waves, and large storms. As sand is trapped by the long leaves of sea oats, vertical growth is stimulated, and rooting occurs at the buried nodes. This plant is extremely drought- and salt-tolerant, grows up to the high tide line of beaches, and propagates both vegetatively and by seed in the wild (Shadow 2007).https://edis.ifas.ufl.edu/sg186 This publication is derived from information in SGEB-75/SG156, Dune Restoration and Enhancement for the Florida Panhandle, by Debbie Miller, Mack Thetford, Christina Verlinde, Gabriel Campbell, and Ashlynn Smith. https://edis.ifas.ufl.edu/sg156.

ENVIRONMENTAL ANALYSIS AND LEGAL BASES FOR COASTAL AREA EVALUATION: THE SEIXAS BEACH SAMPLE - PB

The present work aims at performing an environmental analysis focused on the current legislation applied to Seixas Beach, located in the southern littoral of João Pessoa city, in the State of Paraíba – Brazil. In this coastal zone as well as in other littoral areas of Brazil and Paraíba, natural processes linked to anthropogenical activities have increased coastal erosion, changing significantly the local scenery. This study identified the eminent necessity of applying technical measures that may promote area conservation or the mitigation of present-day erosive processes. Among the implications of disorderly occupation in this coastal space, we observe marked erosion on the coastline that has caused serious socio-economical and landscape damages. Another characteristic of this littoral zone are the elements of civil infrastructure built on permanent preservation areas, including the Average High Tide Line (Marine Line). This fact violates the current environmental legislation in Brazil and contributes noticeably to the degradation of the area.

Jamesiella scotica new to North America from USA, Alaska

Jamesiella scotica is reported new to North America from Kenai Fjords National Park in Alaska. It was found on live and moribund leaves of the bryophyte Paraleucobryum longifolium on sea-shore rocks just above high tide line.