James R. Houston
Florida is the world’s leading tourist destination with 112.4 million out-of-state tourists in 2016. These tourists spent $112 billion and supported one out of every six jobs, making tourism by far Florida’s largest employer. They generated $11.6 billion in local and state taxes, which would be sufficient to pay the salaries of all Florida K-12 teachers, university professors, and local and state law enforcement officers. International tourists alone spent $24.7 billion in Florida, and their spending represents an export value greater than the combined export value of all U.S. corn, wheat, cotton, and other grains that are grown on 42% of all U.S. crop land. Surveys show that beaches are by far Florida’s leading travel destination with more day visits than combined day visits to U.S. National Parks, Corps of Engineers lakes, U.S. theme parks, and the 250 million acres of the U.S. Bureau of Land Management. However, the federal government’s Office of Management and Budget (OMB) opposes beach nourishment, even though Florida beach tourism generates $6.4 billion in federal taxes, and federal navigation projects are the leading cause of Florida beach erosion. Congress ignores OMB and adds limited funding for beach nourishment, and as a result Florida beach tourists generate over $190 in federal taxes for every $1 the federal government spends on beach nourishment. Beach nourishment completely rejuvenated Miami Beach, and international tourists at Miami Beach alone generate annual federal taxes that are almost 30 times greater than federal spending on all Florida beach nourishment. OMB also limits beach recreation benefits to be “incidental” when justifying coastal stormdamage reduction projects, although federal funding of Florida beach nourishment is less than 4% of funding that the federal government spends on recreation facilities at Corps of Engineers’ lakes. If Florida beaches narrow or disappear due to erosion, some domestic and international tourists will choose to vacation at beaches in other states and countries, causing a loss of jobs, taxes, exports, and economic growth in Florida and America.
James Behrens, Eric Terrill, Julianna Thomas, and Robert E. Jensen
The Coastal Data Information Program (CDIP) recorded detailed information about the waves generated by Hurricanes Irma, Jose, and Maria in September 2017, and the January 2018 Bomb Cyclone Nor’easter. The wave fields generated by these storms were measured by an along-coast array comprised of twenty Datawell Directional Waverider moored buoys in the CDIP network. Significant wave height records and maximum individual waves are the focus of this report. The complete quality-controlled directional spectra and displacement data sets, as well as sea surface temperature data, are publicly available at http://cdip.ucsd.edu
Syed M. Khalil, Beth M. Forrest, Edward L. Haywood III, and Richard C. Raynie
Louisiana’s coastline, especially the Mississippi River Deltaic Plain (MRDP), is experiencing some of the most extreme erosion rates in the nation and needs urgent mitigative measures to re-establish a sustainable coastal ecosystem via large-scale restoration. Sedimentological restoration is one of the strategies currently being used to achieve this goal. Sediment management plays a vital role in implementing this strategy. The Louisiana Sediment Management Plan (LASMP) facilitates sediment management for restoration by providing an inventory of potential sediment resources and tracking sediment needs, both of which are crucial to the development of regional strategies for restoration. To aid in the development of Louisiana’s coastal master plan and to help fulfill the goals of the LASMP, first-order surficial sediment distribution maps for offshore and the Lower Mississippi River were developed based on existing geophysical and sedimentological data residing in the Louisiana Sand Resources Database (LASARD). LASARD was initially developed by the state of Louisiana to manage geological, geophysical, geotechnical and other related data pertaining to offshore sand searches. However, with time the scope of LASARD has expanded and it is no longer limited to data related to sand searches only. Keeping the needs of coastal restoration in mind, the sediment deposits that were mapped were broadly classified as surficial sand, surficial mixed sediment, and surficial fines and digitally archived. However, a large portion of offshore areas were classified as “unknown” due to a lack of sufficient reliable data. Based on these maps, first-order total and available (by excluding sediment impacted by oil and gas infrastructure) volume estimates were calculated for sand, mixed sediment, and fine-grained sediment. Based on the 2017 Coastal Master Plan an estimated 5,000 to 11,000 million cubic meters (MCM) of sediment is required to meet coastal Louisiana’s needs. Volume estimates based on the surficial sediment maps indicate that this volume of sediment may be available but dredging all of these sediment resources is not necessarily feasible or technically sound even with sufficient resources. It is important to emphasize that these volumes are first-order estimates as these calculations are based on various geoscientific information with varying degrees of confidence. The development of such maps is a painstakingly intensive effort. These maps are living documents and are updated as new data become available. As such, the mapping is updated periodically and the volumes are updated accordingly. Ultimately the results of the mapping will be available as a digital database. These maps are basic but important tools for resource planning and play a critical role in the management of sediment resources at a regional level. Additionally, these maps are good indicators of presence as well as absence of sufficient geoscientific data. As such, they are a useful tool for conducting data gap analyses, which are typically conducted at planning stages of various investigations. These maps also form templates and/or base maps for development of comprehensive biotic and abiotic habitat maps. Most important, they play a vital role in the enforcement of federal and state regulations related to removal of decommissioned pipelines and coastal zone management. The utility of these maps is not limited to the Louisiana coastal area. Similar maps could be compiled for the entire northern Gulf of Mexico, helping not only the remaining four Gulf states but also supporting Gulf-wide efforts such as the GOMA’s (Gulf of Mexico Alliance) Gulf of Mexico Master Mapping Plan (GMMMP) and RESTORE (Resources and Ecosystem Sustainability, Tourist Opportunities, and Revived Economies) Council’s Coastal Monitoring and Assessment Program (CMAP).
Mariah McBride and Victor J. Viser
A correlation appears to exist between positive fluctuations of the North Atlantic Oscillation (NAO) and above average levels of Sargassum that land along the Gulf of Mexico. Furthermore, there subsists an indirect interconnection between the factors that stimulate a positive placement on the NAO index (i.e. surface water temperature, CO2 absorption rates, and atmospheric pressure) and the average pH level of the Atlantic Ocean. Given the assessment by the Intergovernmental Panel on Climate Change that projects average oceanic pH level decline by 0.4 before the year 2100 (Meehl et al. 2007), the mean NAO Index level and pH level drop recorded between the years 1982 to 2015 were applied as augmentation factors to gauge a hypothetical projection of NAO trends by 2100. Based on these calculations, it appears that the frequency of NAO positive phases could increase, under certain conditions, by a factor of eight. Under these circumstances, it is possible that the resulting positive phase amplification could equate to volumetric increases of Sargassum landings on the Gulf of Mexico shoreline at a similar rate. In addition to the scientific analysis presented, this study also offers suggestions for future research, as well as possible implications for Sargassum mitigation policies.
Bianca Reo Charbonneau and Brenda Casper
Coastal dunes are invaluable natural resources that buffer upland areas. Vegetation is key in dune development and stabilization. Dunes form with sufficient wind, sand source, and obstruction; plants are the ideal obstruction. Storms often erode foredunes and coastal managers replant vegetation to re-establish the necessary obstruction for sand accretion and dune growth. We used a wind tunnel to examine the effect of planting density on bedform formation under constant 18.5 mph (8.25 m/s) winds for 30 min. We filled 1m x 1m x .3 m deep boxes with sand and then planted Ammophila breviligulata plugs in two densities commonly used in management, 12 inches (30.5 cm) and 18 inches (45.7 cm) on center. Sand was supplied by a downwind 1-inch sand bed to mimic backshore transport. We measured the morphology of each plant and used a 3D sensor to record the topography of the bedforms that formed in association with each plant. The bedforms did not vary in volume or basal area as a function of planting density, but biomass was a significant predictor of volume, with larger plants producing larger bedforms. We observed all accretionary bedforms in our low-density treatment, but both erosion and accretion in the high-density treatments potentially due to an inaccurate measure of pre-experiment base height or interactions among neighbors causing greater turbulent kinetic energy with tighter spacing. Bedform height, accretionary or erosive, did not vary by density, row, plant width, or biomass. The bedform shape, measured as the length to width ratio did vary by density; plants in the low-density treatment, despite being morphologically the same, produced bedforms with longer tails. These differences are likely a function of wind backflow and plant interaction interrupting flow, both of which are reduced with a lower planting density. The bedforms created at the onset of planting are thought to carry over through the life of the dune, such that understanding how density affects bedform shape should be considered when making management decisions.
Evan B. Goldstein and Laura J. Moore
Numerical models of coastal dune growth encode feedbacks and nonlinearities between sediment transport and plant growth. The range of processes and tunable parameters involved make model calibration an important step when using models for prediction. In this paper we outline a method to calibrate models of coastal dune formation and describe the process from end to end. The first step is collection of both topographic and vegetation data at two time periods with photogrammetry using the technique of structure-from-motion. Using the first topographic and vegetation capture as the model initial condition, the free parameters in the model are then tuned by running the model many times and adjusting the free parameters with a genetic algorithm, a machine learning technique. A set of parameters is found that produces the lowest prediction error — and in this way the model is calibrated for local conditions. We outline this routine, provide an example, and direct the reader to the open source software developed as part of the workflow presented here, which can be used with other dune models and/or other datasets.