The understanding of recent faulting in the region is an area of emerging research. Glacial isostatic adjustment is related to the existence of the up to 4 kilometer thick Laurentide and Cordilleran ice sheets during the Last Glacial Maximum. Once the ice sheets retreated, the areas that experienced uplift, including the Gulf Coast region, began to subside. Associated subsidence due to glacial isostatic adjustment along the Gulf Coast continues today at rates between 0.
Widely spaced tide gauge-derived rates do not account for the full range of variability in subsidence in the region; rates of RSL rise are likely higher in places with high rates of shallow subsidence such as in coastal Louisiana Nienhuis et al. Compaction is an important process in settings that experience rapid sedimentation. It includes primary consolidation i.
Sediment compaction has long been recognized as a major driver of subsidence in coastal Louisiana Penland and Ramsey, , but separating compaction from other subsidence processes is difficult. Because compaction is so prominent in the shallowest subsurface i. Another potential driver of subsidence along the Gulf Coast is sediment loading. Isostatic adjustment due to sediment loading is a smaller contributor to subsidence i.
The spatial extent of sediment loading, however, is relatively large compared with shallow subsidence processes, and its footprint may extend well beyond the actual area of sediment deposition. Finally, the withdrawal of subsurface fluids can play an important role in Gulf Coast subsidence.
Fluid withdrawal can take place at multiple depths across the sedimentary column and a variety of fluids can be withdrawn e. In urban areas such as New Orleans and Houston, groundwater is often pumped out as part of stormwater management actions. The resulting desiccation and increased oxidation rates of buried organic matter cause further subsidence e. A prominent example of this is metropolitan New Orleans,. Groundwater withdrawal has also been associated with up to 3 meters of subsidence in Galveston and Houston Winslow and Doyel, ; Kasmarek, Groundwater is also removed from the subsurface for industrial purposes.
Jones et al. Oil and gas withdrawal is also associated with subsidence elsewhere along the Gulf Coast. Spatial and temporal patterns in subsidence across Louisiana are correlated with hydrocarbon and water withdrawal and can be related to regional wetland loss Morton et al. White and Tremblay suggest that oil and gas withdrawal in Texas is associated with regional patterns of subsidence and wetland loss, and that this withdrawal may have activated faults along the Texas Gulf Coast.
The Gulf of Mexico receives approximately cubic kilometers km 3 of water each year, including contributions from episodic riverine flood events. The Mississippi River system is the dominant source of freshwater to the Gulf, delivering about km 3 of freshwater through the main stem of the Mississippi River and an additional km 3 of freshwater through the Atchafalaya distributary.
The next largest sources of freshwater are the Mobile 60 km 3 , Apalachicola Moderate-sized rivers include the Brazos, Pascagoula, Pearl, Suwannee, and Trinity Rivers, which each discharge 7 km 3 to 10 km 3 per year Dunn, ; Allison et al. The amount of rainfall along the Gulf Coast can vary on seasonal, annual, and longer e. In addition, episodic weather events such as tropical cyclones may produce much larger amounts of rainfall over hours than the total quantity accumulated over months prior to storm arrival.
As climate change alters patterns of rainfall, the magnitude and timing of freshwater delivery to the Gulf Coast may also vary. Increased freshwater delivery during short time periods may result in substantial flooding in the coastal zone, particularly in highly urbanized settings with substantial hydrological alterations, especially if coincident with storm-induced surge. The Gulf Coast is exposed to an average rate of three to four hurricane landfalls per decade e.
Forerunner surge inundation i. Eight of the top 10 most costly U. The very large spatial extents and intensities of Hurricanes Katrina and Ike led to widespread, high storm surge Irish et al. Hurricane Ike, with its large forerunner surge Kennedy et al. Flooding in inland areas is generally controlled by the balance between storm surge and freshwater drainage. During Hurricane Harvey, some areas of coastal Texas were inundated with storm surge, but the record-breaking damage and inundation in the Houston metropolitan area was dominated by rainfall-related flooding.
Later that same year, Hurricane Irma caused widespread damage across Florida. The exacerbation of hurricane impacts along the Gulf Coast by the combined influence of sea level rise and urban growth cannot be overlooked. RSL rise and substantial wetland.
TABLE 2. Yet, the impact of local sea level rise and long-term changes in land cover and topography on hurricane-driven inundation is complex and difficult to predict with confidence Bilskie et al. Such impacts vary depending on geographic location and storm track characteristics Atkinson et al.
RSL rise and coastal change, coupled with human development, will be the leading driver of hurricane flood hazard acceleration along low-lying sedimentary coasts such as the Gulf Coast Woodruff et al. An example from outside the Gulf is the New York metro region, where flood elevations over a range of annual exceedance probabilities e. In areas farther inland, however, the influence of sea level rise on flood elevation may not be well captured by linearly adding present-day hazard curves to projected sea level rise.
For example, the predicted relative increase in surge hazard in the bays of Panama City, Florida, is not linear with sea level rise. It either increases more slowly at a rate as little as 85 percent or more quickly at a rate as much as percent than sea level rise, depending on the location Taylor et al. Levees, floodwalls, storm gates, and other infrastructure designed to reduce storm damage in specific geographic areas might impact storm surge and create damage in other nearby areas.
When surge is prevented from entering the area landward of such a structure, the blocked water either then increases surge locally along the seaward side of the structure or will be redirected elsewhere.
Often the response is for water to collect outside the area of protective infrastructure, increasing flood risks for homes and urban structures in that location. For example, the Louisiana Coastal Master Plan shows an increase in year flood storm surges 50 years into the future for areas outside of the levees and other hard infrastructure see Figure 2.
Across the Gulf Coast, new levees are in various stages of planning, construction, and completion. The Mississippi River system is the dominant source of sediment for the Gulf system. Coastal environments west of Mobile Bay, Alabama, are typically dominated by turbid waters, while coastal environments to its east typically feature clearer waters Herrera-Silveira and Morales-Ojeda, ; Dzwonkowski et al.
These differences stem, in part, from the nature of the river drainage basins. The Mississippi and Atchafalaya Rivers have a continental scale drainage basin that drains approximately 41 percent of the United States and contains diverse habitats including forests, farmland, arid lands, and cities; whereas many other rivers have regional-scale drainage basins with more homogenous land uses Alexander et al.
Because of their large absolute magnitude, the central Gulf rivers are important for both sediment and freshwater inputs Horowitz et al. Sediment budgets for the Mississippi River suggest that more than half of the sediment that enters at Tarbert Landing along the Mississippi—Louisiana border is trapped in the river channel or is transported to distributary channels near the river Allison et al.
Sediment sources within the Gulf of Mexico include offshore deposits from river discharge during periods of lower sea level and earlier periods in the Holocene Epoch, longshore drift from modern rivers, subsidence of coastal landforms, and biogenic production Khalil et al. Sediments are available to be transported landward during normal coastal processes and during storm and overwash events and can be dredged for projects such as coastal restoration or mitigation of coastal erosion Morang, ; Hickey et al.
These sediments are reworked by coastal hydrodynamics arising from tides, waves, and flooding during episodic coastal storms. Esposito et al. Most of the Texas shoreline is characterized by a mixed tide regime, while in Alabama, Louisiana, and Mississippi the tides are diurnal.
The west Florida shoreline has semi-diurnal tides in the northern part of the state and mixed tides in the southern part Eleuterius and Beaugez, With rising sea levels, tides will be propagating on deeper water and tide components will change slightly.
Pickering et al. With shoreline recession, the tidal amplitude changes will be less. Waves are the principle driving force for coastal processes. The Gulf of Mexico is a low-energy coastline, with nonstorm wave heights on the order of 0. Results based on a year hindcast Appendini et al. Peak wave period values along the Gulf are generally 5 to 8 seconds, with the longer periods occurring in the eastern Gulf Appendini et al.
Panchang et al. They also showed an increase in maximum annual significant wave height with time in the eastern part of the Gulf. Appendini et al. The geological record indicates that Gulf Coast bays and estuaries have a history of rapid and dramatic change in response to changes in sediment supply and RSL rise.
Bay-head deltas, often found within coastal bays, are particularly sensitive to the balance between sea level rise and sediment input. When sediment input is sufficient, these deltas may grow despite rapid rates of RSL rise e.
Systems such as the Trinity River within the Galveston Bay estuary complex or Mobile River Deltas, with substantially less sediment supply, are likely to see land loss in the long term Weston, Many of the estuaries and bays of the Gulf Coast are fronted by sandy barrier islands and peninsulas. The remainder of the ocean coastline consists of marsh, bluff, and sandy mainland beaches. As sea level continues to rise, sandy coastline response will depend largely on the balance between the rates of sediment supply and RSL rise.
When there is a sediment deficit, the shoreline will erode; when rates are balanced, shoreline position may remain stable over the long term. In the case of barrier island or sandy peninsula shorelines, when the rate of RSL rise outpaces rates of sediment supply, shoreline erosion can lead to. If sea level rise continues to outpace rates of sediment supply, landward migration will likely occur when barrier islands or peninsulas become narrow enough for storms to impact their entire width Leatherman, Migration is facilitated by overwash processes, which occur when the combination of tides, storm surge, and wave action brings the water level above the height of the frontal dune or berm e.
Overwash carries sand from the front of a barrier or peninsula to the interior of the landform. In this way, storms promote the maintenance of islands and sandy peninsulas by building them upward and moving them landward, thereby maintaining island elevation relative to sea level as sea level rises. Barriers constructed from muddy deltaic deposits require a greater amount of landward migration to liberate the same amount of sand, compared with locations where the substrate contains a higher proportion of sand Moore et al.
As a result, deltaic barriers are more vulnerable to disintegration than barriers underlain by sand e. In general, shoreline erosion rates are highest up to In contrast, barrier islands in Mississippi are migrating laterally Morton, ; Otvos and Carter, due to net alongshore sediment transport rates in this region. Interactions between vegetation and sediment transport cause localized sand deposition in the presence of beach grasses, giving rise to coastal dunes. When present, dunes may provide protection to inland habitats and coastal infrastructure by reducing vulnerability to overwash and flooding during storms.
For this reason, dunes are sometimes constructed as part of beach nourishment efforts designed to provide recreational beaches and storm protection. Other coastal management strategies, including seawall construction or groin emplacement, are sometimes undertaken in an attempt to maintain shoreline position.
Some of these strategies have been supplanted by beach nourishment efforts Morton et al. They also block the transfer of overwash sediment to the back-beach and back-barrier environments, with potentially detrimental long-term effects. Other residential and commercial infrastructure can also have this effect, as demonstrated by a field study of several sites in New Jersey affected by Hurricane Sandy, where buildings and a boardwalk blocked the delivery of up to 90 percent of overwash sand Rogers et al.
A companion modeling effort suggests this has the potential to prevent barriers from building upward and migrating landward, thus hastening island disintegration or drowning as sea level rises Rogers et al.
Barrier islands are most able to maintain elevation above sea level when they retain their mobility. It is the spreading, herbaceous species such as dune grasses, rather than rigid and tall woody growth form, that promote sediment accretion and increases in elevation Feagin et al.
If coastal management plans focus instead on sediment stabilization and the attainment of later stages of vegetation succession, such as maritime forest, the system as a whole would lose its natural resiliency.
When the substrate is no longer mobile, early successional stages disappear and colonizer species that are tolerant of burial under sand become locally extinct. Roman and Nordstrom concluded that human-induced sediment starvation has profound effects on barrier island vegetation, including a threshold shoreline erosion rate beyond which vegetation does not recover.
The exact magnitude of this threshold may vary among barrier islands and depends on shoreline orientation, tidal range, storm frequency, and the ability of native plants to bind sand Roman and Nordstrom, ; Tsoar, Forecasting the future behavior of the physical coastal system is challenging, but there are several ways that projections of future coastline position and landform state can be done.
The first is to use the historical behavior of the shoreline or marshes, such as erosion rates over decades or vegetation growth rates, and to extrapolate these rates into the future. These empirical data-driven models have been used for short-term changes i. For example, sea level is currently rising far faster than before, and so erosion rates in the future may be far higher than what has occurred in the past several thousand years. Coastal evolution models, which simulate the evolution of the physical parts of the system, can be categorized by considering the domain across which a model operates and its underlying assumptions.
For instance, coastal profile models only consider variations in water depth and topography in the onshore—offshore direction, either neglecting or parameterizing the effects of longshore variation e. Coastal area models allow the water depth to change in both the cross-shore and the alongshore direction e. Coastal evolution models can also be classified according to whether they include all the relevant processes at the smallest scale practical e.
Paola refers to these two types of models as reductionist or synthesist i. Because synthesist models are sometimes used in a predictive sense, the Paola framework is used here. Reductionist models explicitly account for the bathymetric evolution via sediment transport formulations that directly link the mobilizing and transport of sediment to hydrodynamics.
These models are often used for short-term events, such as bar migration or barrier island evolution, over timescales of days to weeks. The synthesist models are based on reduced-complexity formulations developed by choosing macroscale variables to drive the model, such as sediment transport rates, which inherently consider all the sediment transport modes and physics, but use simplified relationships instead of explicitly calculating them as a function of the overlying hydrodynamics.
Even further abstractions are possible: Pape et al. Reduced-complexity models can produce qualitatively reasonable behavior and some can be used to quickly explore parameter space within the context in support of engineering design, management planning, and decision making.
Gulf Coast ecosystems are highly diverse and provide essential services that are key in sustaining human and wildlife populations de Groot et al. The dynamics, structure, and function of these ecosystems are broadly influenced by sharp environmental gradients that extend from the western to the eastern Gulf Coast, as well as substantial temporal variability that operates at different scales, ranging from episodic to seasonal to inter-annual. Human modifications of the coastal landscape, as well as climate change, also affect coastal ecosystems.
Given the many interactions that can occur among natural environmental gradients, temporal variability, human coastal modifications, and changing climate, the impacts of such interactions on Gulf Coast ecosystems can be quite complex. There are a multitude of ecological habitats along the Gulf Coast, including submerged sediments, wetlands, woodlands, and xeric dunes see Figure 2. Wetlands fringe the coastline at the interface between land and the open waters of bays, lagoons, and the Gulf, comprising marshes and mangroves that are adapted to varying climate, seawater flooding, and salinity levels.
Sugarland - Victoria - Wharton - Learn more about Endangered and Threatened Plants. Learn more about these animals on our Wildlife Fact Sheets. Attwater's prairie chicken: Tall grass coastal prairie Eastern brown pelican: Offshore islands, spoil islands, mudbanks Eskimo curlew: Migrates through the grasslands from the Arctic tundra to Pampas grasslands of Argentina Piping plover: Winters along Gulf Coast; tidal mud flats, sandflats, or algal flats Whooping crane: Winters on Texas Gulf Coast; marshes and sandflats of Aransas.
Learn more about Endangered and Threatened Species. Regions of Texas. The county Gulf Coast region covers about 13, square miles in eastern coastal Texas, stretching from Huntsville on the north to Matagorda Bay and Galveston along the Gulf Coast. This report examines regional economic trends including population, household income, jobs and wages, and education, as well as economic conditions unique to the Gulf Coast region.
This represented an increase of about 19 percent more than 1 million people since the Census. While the population of most counties in the region increased during this period, Fort Bend outpaced all others, growing by more than 38 percent — more than twice the rate of the state. According to the U. About A high LQ can identify industries that have a competitive advantage in the region, such as the ability to produce products more efficiently and of a higher quality.
Based on location quotients, the Gulf Coast region is a leader in the oil and gas extraction, pipeline transportation, and space research and technology industries. Data are as of Q4 except wage data, which are for covered employment in Source: JobsEQ. Texas has 14 U. The marshlands along the Louisiana and Texas coasts provide breeding grounds and nurseries for ocean life that drive the fishing and shrimping industries.
As of , seven of the top ten busiest ports in the U. The discovery of oil and gas deposits along the coast and offshore, combined with easy access to shipping, have made the Gulf Coast the heart of the U. The coast contains nearly 4, oil platforms.
Besides the above, the region features other important industries including aerospace and biomedical research, as well as older industries such as agriculture and — especially since the development of the Gulf Coast beginning in the s and the increase in wealth throughout the United States — tourism. The history of the Gulf Coast is an important part of United States history; as economically important as the Gulf Coast is to the United States today, it arguably once held an even greater position of prominence in the U.
Before Europeans arrived in the region, the region was home to several pre-Columbian kingdoms that had extensive trade networks with empires such as the Aztecs and the Mississippi Mound Builders. Shark and alligator teeth and shells from the Gulf have been found as far north as Ohio, in the mounds of the Hopewell culture.
As the U. The development of sugar and cotton production enabled by slavery allowed the South to prosper. By the mid 19th century the city of New Orleans , being situated as a key to commerce on the Mississippi River and in the Gulf, had become the largest U.
Two major events were turning points in the earlier history of the Gulf Coast region. The first was the American Civil War , which caused severe damage to some economic sectors in the South , including the Gulf Coast.
The second event was the Galveston Hurricane of At the end of the 19th century Galveston was, with New Orleans, one of the most developed cities in the region. The city had the third busiest port in the U. Since these darker times the Gulf Coast has been hit with numerous other hurricanes.
Again in the Gulf Coast was struck by a catastrophic hurricane. Due to its immense size, Hurricane Ike caused devastation from the Louisiana coastline all the way to the Kenedy County, Texas region near Corpus Christi.
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