Overview of Research into the Coastal Effects of the Macondo Blowout from the Coastal Waters Consortium: A GoMRI Consortium

ABSTRACT The Coastal Waters Consortium (CWC) led by Louisiana Universities Marine Consortium is one of eight Gulf of Mexico Research Initiative research consortia. The CWC focuses on: oil transport and fate, chemical evolution and biological degradation, and environmental effects.The following is an overview of a portion of the research conducted within the consortium. The consortium works in a system that was impacted by the Deepwater Horizon oil disaster and additionally impacted by freshwater diversions resulting in changes in salinity, tropical storms, and hurricanes. First, we conducted model simulations assessing oil transport into the Barataria Bay estuary, which indicate that easterly winds and feeding of the anticyclonic gyre in the Louisiana Bight pushed the oil into Barataria Bay. In subtidal sediments adjacent to oiled marshes, marsh detritus from eroding marsh edges eventually became entrained in the sediment column. Biotic impacts vary. The above-ground plant biomass appears healthy at the individual sampling sites; overall the most seaward (i.e., likely oil-impacted) areas of Terrebonne and Barataria Bay have shown, via satellite data, a distinct decline in marsh vegetation coverage since 2010. Oysters appear to be affected by predation and salinity variation. Microbial diversity from marsh-edge sediments is distinct from before and after the spill, and between unoiled and oiled marshes, with lower diversity in oiled marshes; but the greatest community composition shifts are in marshes affected by the freshwater diversions. Changes in microbial diversity in the water column at the stream-side edge of oiled marshes are extensive and are related to marsh edge erosion. In contrast, oiling of marshes had no impact on ammonia oxidizer or denitrifier abundances and on soil biogeochemical process rates 2+ years post-spill. Analysis of long-term offshore phytoplankton community and hypoxia data indicate some signal of the Macondo oil, but these components of the ecosystem remain mostly influenced by the fresh water and nutrients delivered by the Mississippi River. The consortium continues to work to tease apart oil impacts, effects of salinity, natural variation, and disturbance from tropical storms and hurricanes to determine the trajectory for health of shelf waters and Louisiana's marshes.

Comparative assessment of water markets: insights from the Murray–Darling Basin of Australia and the Western USA

Water markets in Australia's Murray–Darling Basin (MDB) and the western USA are compared in terms of their ability to allocate scarce water resources. The study finds that the gains from trade in the MDB are worth hundreds of millions of dollars per year (note that all monetary units of dollars in this article are treated as US$ because Australian$ are converted at par). Total market turnover in water rights exceeds US$2 billion per year while the volume of trade exceeds over 20% of surface water extractions. In Arizona, California, Colorado, Nevada and Texas, trades of committed water annually range between 5 and 15% of total state freshwater diversions with over US$4.3 billion (2008 US$; monetary units in dollars are expressed in their value in US$ in 2008) spent or committed by urban buyers between 1987 and 2008. The two-market comparison suggests that policy attention should be directed towards ways of promoting water trade while simultaneously mitigating the legitimate third party concerns about how and where water is used, especially in conflicts between consumptive and in situ uses of water. The study finds that institutional innovation is feasible in both countries and that further understanding about the size, duration and distribution of third party effects from water trade and how these effects might be regulated, can improve water markets' ability to manage water scarcity better.

NUMERICAL MODELING OF OIL SPILLS IN THE INLAND WATERWAYS OF THE LOWER MISSISSIPPI RIVER DELTA

ABSTRACT The demand for fossil fuels is driving the rapid expansion of the petroleum industry'S infrastructure. Louisiana'S wetlands are the most industrialized in the world. The oil industry has infiltrated every part of the Lower Mississippi River Delta (LMRD) from the fixed facilities and transport vessels traveling along inland waterways, the pipelines and canals running through the wetlands, and the offshore platforms along the Gulf of Mexico coastline. An oil spill could seriously damage the coastal wetlands that are already rapidly degrading, pollute the water supply, destroy wildlife habitat, and impact other natural economic and social resources. Additionally, proposed coastal restoration initiatives such as freshwater diversions could provide a conduit for spills to travel from the river to open wetland areas. Current inland oil fate and transport models cannot automatically be applied in the deltaic environment because they do not represent the high degree of minerals and fines in suspension, the unique characteristics of the shorelines, or the potential flow into the wetland areas. Thus, a three- dimensional oil fate and transport model was developed to investigate the behavior of oil spilled in the unique environment of the LMRD, assess the vulnerability at specific locations such as freshwater diversions from the river, and provide information for contingency and remediation plans. Simulations of the hydrodynamics of the LMRD were generated using the U.S. Army Corps of Engineers Adaptive Hydraulics (ADH) modeling code. The model simulates the physical and chemical processes affecting the fate of a surface oil spill including slick advection and spreading, the vertical transport of dissolved and emulsified parcels, evaporation, dissolution, adsorption, sedimentation, re-suspension and degradation. The model estimates the distribution of oil in the surface slick, water column, sediments and atmosphere. Almost seventy percent of the Mississippi River'S sediment load is comprised of finer materials. The model is unique in using empirical predictions to describe oil'S interactions with fine suspended material and muddy shorelines. Hypothetical spills representative of the type and location of spills commonly occurring in the region were simulated to investigate the sensitivity of the system to the unique parameters. This model was developed to take advantage of the latest advances in computational fluid dynamics and weathering algorithms, while focusing on the complex hydraulics and sediment characteristics local to the Lower Mississippi River Delta.