Geology topics

Research about Louisiana

Source-linked reports with geographic coverage including Louisiana.

At least 181 records · Page 10Linked to original sources

USGS2019

Water resources of Jackson Parish, Louisiana

Information concerning the availability, use, and quality of water in Jackson Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 4.38 million gallons per day (Mgal/d) of water were withdrawn in Jackson Parish: 4.36 Mgal/d from groundwater sources and 0.02 Mgal/d from surface-water sources. Withdrawals for public-supply use accounted for about 42 percent (1.85 Mgal/d) of the total water withdrawn, and industrial use accounted for about 54 percent (2.36 Mgal/d). Other categories of use included livestock and rural domestic. Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicate that water withdrawals peaked in 1975 at about 15.26 Mgal/d. The significant decrease in water use from 1975 to 1980 was caused by a reduction of 10.38 Mgal/d in withdrawals for industrial use.

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USGS2019

Limpkin, Aramus guarauna (L., 1766) (Gruiformes, Aramidae), extralimital breeding in Louisiana is associated with availability of the invasive Giant Apple Snail, Pomacea maculata Perry, 1810 (Caenogastropoda, Ampullariidae)

We document the first breeding record of Limpkin, Aramus guarauna (Linnaeus, 1766) (Gruiformes, Aramidae), for Louisiana, describe an additional unpublished breeding record from Georgia, as well as a possible record from Alabama, and associate these patterns with the concurrent establishment of the invasive Giant Apple Snail, Pomacea maculata Perry, 1810 (Caenogastropoda, Ampullariidae). We predict that an invasive prey species may facilitate range expansion by native predator species, which has ramifications for conservation and management.

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USGS2019

Water resources of Richland Parish, Louisiana

Information concerning the availability, use, and quality of water in Richland Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 41.73 million gallons per day (Mgal/d) of water were withdrawn in Richland Parish, including about 28.57 Mgal/d from groundwater sources and 13.17 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of general irrigation, rice irrigation, aquaculture, and livestock uses, accounted for about 88 percent (36.88 Mgal/d) of the total water withdrawn. Other categories of use included public supply, which accounted for about 10 percent (4.38 Mgal/d) of the total water withdrawn and rural domestic which accounted for about 1 percent (0.48 Mgal/d). Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicate that water withdrawals peaked in 1980 at more than 60 Mgal/d.

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USGS2019

Water resources of Tensas Parish, Louisiana

Information concerning the availability, use, and quality of water in Tensas Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, 38.01 million gallons per day (Mgal/d) of water were withdrawn in Tensas Parish, including about 33.02 Mgal/d from groundwater sources and about 4.99 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of general irrigation, rice irrigation, aquaculture, and livestock, accounted for about 97 percent (36.88 Mgal/d) of the total water withdrawn. Other use categories included public supply and rural domestic. Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 2014. The large increase in 1985 relative to 1980 and 1990 for groundwater usage is likely an outlier that is attributable to a change in methodology for estimating rice irrigation. A transition in available farm-by-farm data from 1980 to 1985 to 1990 resulted in three different methods being used for estimating groundwater withdrawals for rice irrigation.

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USGS2019

Water resources of Morehouse Parish, Louisiana

Information concerning the availability, use, and quality of water in Morehouse Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, 109.84 million gallons per day (Mgal/d) of water were withdrawn in Morehouse Parish: 78.05 Mgal/d from groundwater sources and 31.79 Mgal/d from surface-water sources. Withdrawals for agricultural use—including general irrigation, rice irrigation, and livestock—accounted for about 97 percent (106.29 Mgal/d) of the total water withdrawn. Other categories of use included public supply, rural domestic, and industrial. Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 1975 at 167.82 Mgal/d.

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USGS2019

Water Resources of West Carroll Parish, Louisiana

Information concerning the availability, use, and quality of water in West Carroll Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, 21.27 million gallons per day (Mgal/d) of water were withdrawn in West Carroll Parish, including 17.91 Mgal/d from groundwater sources and 3.37 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of general irrigation, rice irrigation, and livestock, accounted for 93 percent (19.76 Mgal/d) of the total water withdrawn. Other use categories included public supply and rural domestic. Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 2000 at 31.7 Mgal/d. The large decreases in water use from 1985 to 1990 and again from 2005 to 2010 are primarily attributable to declines in groundwater withdrawals for rice irrigation from 10 Mgal/d in 1985 to 2.22 Mgal/d in 1990 and from 10.52 Mgal/d in 2005 to 5.14 Mgal/d in 2010. Surface-water withdrawals for general irrigation declined from 2.44 Mgal/d in 1985 to 0.42 Mgal/d in 1990 and from 2.2 Mgal/d in 2005 to 1.1 Mgal/d in 2010. Surface-water withdrawals for rice irrigation declined from 1.41 Mgal/d in 1985 to 0.66 Mgal/d in 1990 and from 2.06 Mgal/d in 2005 to 1.01 Mgal/d in 2010.

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USGS2019

Flood-inundation maps for the Amite and Comite Rivers from State Highway 64 to U.S. Highway 190 at Central, Louisiana

Flood-inundation maps for a 14.5-mile reach of the Amite River and a 20.2-mile reach of the Comite River from State Highway 64 to U.S. Highway 190 were created by the U.S. Geological Survey (USGS) in cooperation with the City of Central, Louisiana. These maps, which can be accessed through an interactive mapper at the USGS Flood Inundation Mapping Program website and from a companion USGS data release, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgages Amite River at Magnolia, La., (07377300) and Comite River near Comite, La. (07378000). Flood profiles were computed for the Amite and Comite River reaches by using the two-dimensional (2D), finite-volume numerical modeling options in the U.S. Army Corps of Engineers Hydrologic Engineering Center’s River Analysis System (USACE HEC-RAS) software version 5.0.3. Models were calibrated to the current (2018) stage-discharge relations at the Amite River at Magnolia, La., and Comite River near Comite, La., streamgages, water-surface profiles from the March and August 2016 floods, and documented high-water marks from the flood of August 2016. The hydraulic models were used to compute 37 individual water-surface profiles (21 for the Amite River and 16 for the Comite River) at 1.0-foot intervals ranging from the National Weather Service flood stage to the highest peak on record at the two streamgages. The 37 simulated water-surface profiles were used with a light detection and ranging-derived digital elevation model to delineate the flood extent and associated depth at each water level. The delineated areas (inundation maps) were merged into 127 combinations or possible flooding scenarios based on annual peak stage information from the two streamgaging stations. The availability of these maps, along with real-time data delivered via the internet, will provide emergency management personnel and residents with information that is critical for flood-response activities such as evacuations and road closures, as well as for recovery efforts after floods.

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USGS2019

Restoration affects sexual reproductive capacity in a salt marsh

Plant sexual reproduction is an important driver of plant community maintenance, dispersal, and recovery from disturbance. Despite this, sexual reproduction in habitats dominated by clonally spreading perennial species, such as salt marshes, is often ignored. Communities dominated by long-lived perennial species can still depend on sexual reproduction for recolonizing large disturbed patches or for establishing in new patches, such as restored sites. We investigated the influence of restoration and elevation on flowering phenology, potential seed and seedling production, and insect flower damage of the dominant salt marsh grass, Spartina alterniflora , in reference and restored marshes in southeastern Louisiana, USA. We additionally tested whether elevation gradients or soil parameters could explain differences in sexual reproduction between sites. We demonstrate that sediment-slurry amendment restoration may not affect flowering phenology or insect flower damage at ecologically relevant levels, but that restoration activity increases sexual reproductive output at the patch scale. Restoration activity affected reproductive dynamics more often than changes in elevation alone. Restoration of subsiding salt marsh habitat by altering the soil environment may increase sexual reproductive capacity of these wetlands.

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USGS2019

Potential sea level rise for the Chitimacha Tribe of Louisiana

Situated in the Mississippi Alluvial Plain of the Gulf Coast Prairie Landscape Conservation Cooperative (GCP LCC), the Chitimacha Tribe is one of four federally recognized tribes in Louisiana. The Tribal seat, trust lands/ reservation, and adjacent Tribal owned lands are located near Charenton, Louisiana, totaling nearly 1,000 acres. The Chitimacha, with a population of approximately 1,400 people, are currently impacted by storm surge, which is expected to increase with climate change. The additional stress from storms will likewise increase the vulnerability to catastrophic impact in the event of a breach in the Atchafalaya Basin Spillway levee. A collaborative effort between the U.S. Geological Survey (USGS) and the Chitimacha Tribe has been initiated to provide resources and expertise to increase the Tribe’s ability to prevent, plan, and prepare for these environmental challenges. By enhancing technical skills, providing access to environmental data, and increasing awareness of environmental issues, the Chitimacha will be better prepared to plan and adapt to the environmental impacts facing their lands related to land use and climate change. For this project, USGS researchers asked how Chitimacha Tribal Lands might be impacted by future sea level rise scenario projections. These models illustrate some flooding within the northernmost boundary of Chitimacha Tribal Lands.

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USGS2019

Sediment trapping and carbon sequestration in floodplains of the lower Atchafalaya Basin, LA: Allochthonous vs. autochthonous carbon sources

Recent studies suggest that about 2 Pg of organic C is stored on floodplains worldwide. The present study indicates the Atchafalaya River, fifth largest river in the United States in terms of discharge, traps 30 mm/y of sediment on average within its floodplain, which is the highest average non‐episodic rate of fluvial deposition on the U.S. Coastal Plain. We installed sediment sampling stations at 23 sites, normally in transect, in the Atchafalaya Basin; these sites represent the range of hydrogeomorphic conditions on the floodplain based on hydrologic connectivity with the river main stem. The rate of sedimentation translates into about 12.5 Tg/y and includes 694 Mg/y of organic C. Highest sedimentation rates are associated with areas of high connectivity to channels and prograding deltaic processes. The δ 13 C content suggests that 35% of deposited C is derived from river‐suspended sediment compared to litterfall in the Basin. Thus, much of the organic C sequestered is allochthonous material. However, isolated interior sites with limited connectivity to the channel may generate and sequester large amounts of autochthonous C. The substantial trapping of both auto‐ and allochthonous C (392 Mg/y) make this freshwater‐forested floodplain critical in storage of material before reaching the coastal delta and estuary. This C deposition rate (340 g C m ‐2 y ‐1 ) exceeds all other rates reported in recent Blue Carbon and Tidal Freshwater Forested Wetland studies. Atchafalaya C sequestration occurs in/near areas with tidal influence and like other coastal systems is an important site for trapping mineral and organic sediment and in global C cycling.

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USGS2019

Patterning emergent marsh vegetation assemblages in coastal Louisiana, USA, with unsupervised artificial neural networks

Question Are self‐organizing maps (SOMs) useful for patterning coastal wetland vegetation communities? Do SOMs provide robust alternatives to traditional classification methods, particularly when underlying species response functions are unknown or difficult to approximate, or when a need exists to continuously classify new samples obtained under ongoing long‐term ecosystem monitoring programs as they become available?. Location Coastal Louisiana, USA. Methods A SOM was trained from in situ observations of 559 vegetation species relative cover data from 2526 samples collected over eight years at 343 locations across coastal Louisiana. Hierarchical cluster analysis was applied to the SOM output to delineate vegetation community types, and indicator species analysis was conducted. Salinity and flood duration were compared across the delineated community types. Results The SOM patterned the 2526 training samples into 260 output neurons, which were further clustered into eleven community types. Clear gradients in salinity and flood duration existed among the community types, and geographic zonation of the communities was evident across the landscape. At some locations assemblages were temporally stable; at other locations they varied considerably. Samples not used in training the network were effectively projected onto the SOM and assigned to one of the delineated community types. Conclusions The SOM was effective in delineating plant communities in the region that were qualitatively similar to those obtained in previous investigations. Being robust to skewed distributions and the presence of outliers, SOMs provide an alternative to traditional distribution‐based statistical approaches. Their ability to efficiently classify new data into existing community types makes their use an ideal approach to classifying samples obtained from ongoing, long‐term ecological monitoring programs.

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USGS2019

Mississippi river sediment diversions and coastal wetland sustainability: Synthesis of responses to freshwater, sediment, and nutrient inputs

Management and restoration of coastal wetlands require insight into how inundation, salinity, and the availability of mineral sediment and nutrients interact to influence ecosystem functions that control sustainability. The Mississippi River Delta, which ranks among the world's largest and most productive coastal wetland complexes, has experienced extensive deterioration over the last century due, in large part, to enhanced vulnerability to relative sea-level rise and lateral erosion caused by a combination of natural processes and anthropogenic modifications of hydrology. This land loss crisis has prompted the State of Louisiana to develop a comprehensive restoration plan that includes constructing and implementing a series of large-scale sediment diversions that will reconnect sediment- and nutrient-rich Mississippi River water to adjacent bays, estuaries, and wetlands. Sediment loading through diversions is predicted to enhance the long-term sustainability of coastal wetlands; however, the additive effects of increased inundation, abrubt changes in the salinity regime, and high nutrient loads on wetland plant growth and organic matter (SOM) decomposition rates, which help regulate accretion and elevation change, is uncertain. Therefore, this review attempts to synthesize existing information to inform predictions of the interactive effects of diversions on these drivers of coastal wetland sustainability. The data suggest that sediment deposition within an optimal elevation range will increase the overall productivity of existing wetlands where prolonged flooding does not counter this effect by limiting plant growth. A reduction in salinity may increase plant productivity and cause vegetation shifts to less salt tolerant species, but seasonal swings in salinity may have unforeseen consequences. Nutrient-loading is predicted to lead to greater aboveground productivity, which, in turn, can facilitate additional sediment trapping; however, belowground productivity may decline, particularly in areas where sediment deposition is limited. In areas experiencing net deposition, nutrient-enrichment is predicted to enhance belowground growth into new sediment and contribute to positive effects on soil organic matter accumulation, accretion, and elevation change. Thus, we contend that sediment input is essential for limiting the negative effects of flooding and nutrient-enrichment on wetland processes. These conclusions are generally supported by the biophysical feedbacks occurring in existing prograding deltas of the Mississippi River Delta complex.

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USGS2019

Drivers and impacts of water level fluctuations in the Mississippi River delta: Implications for delta restoration

This review synthesizes the knowledge regarding the environmental forces affecting water level variability in the coastal waters of the Mississippi River delta and relates these fluctuations to planned river diversions. Water level fluctuations vary significantly across temporal and spatial scales, and are subject to influences from river flow, tides, vegetation, atmospheric forcing, climate change, and anthropogenic activities. Human impacts have strongly affected water level variability in the Mississippi River delta and other deltas worldwide. Collectively, the research reviewed in this article is important for enhancing environmental, economic, and social resilience and sustainability by assessing, mitigating, and adapting to geophysical changes that will cascade to societal systems in the coming decades in the economically and environmentally important Mississippi River delta. Specifically, this information provides a context within which to evaluate the impacts of diversions on the hydrology of the Mississippi delta and creates a benchmark for the evaluation of the impact of water level fluctuations on coastal restoration projects worldwide.

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USGS2019

Canals, backfilling and wetland loss in the Mississippi Delta

Canals and spoil banks have contributed significantly to high rates of wetland loss in the Mississippi delta. There has been relatively little research on management of canals and spoil banks and this needs to be a significant component of restoration of the delta. We analyze research on the role of backfilling canals in the context of delta restoration with special reference to Turner and McClenachan (2018) who state that if all canals were backfilled, it could significantly reduce or even reverse wetland loss and that most wetland loss is caused by canals. We agree with T&M that canals have been a significant cause of wetland loss in the Mississippi Delta and that removing spoil banks and backfilling canals should be an integral part of delta restoration. However, a number of factors need to be considered when choosing which canals to backfill including possible enhanced erosion due to exposure to wave action for newly created and remnant marsh, the current and future production history of oil and natural gas from canals, and other restoration activities in oil and gas fields. Turner and McClenachan’s analysis using wetland loss patterns in 15-minute quadrangles suggesting that canal density can explain most wetland loss in coastal Louisiana is flawed because of scale problems and other impacts of oil and gas activity. These impacts include subsurface induced subsidence and the impact of produced water and toxins on wetlands that are largely unrelated to surface alteration due to canals and spoil banks.

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USGS2019

Patterns of resource allocation in a coastal marsh plant (Schoenoplectus americanus) along a sediment-addition gradient

Reductions in sediment delivery to coastal marshes increase their vulnerability to relative sea-level rise. Sediment pulses from storm events and commercial dredge-spray operations (e.g., beneficial use) represent increasingly important sediment sources to otherwise sediment-deprived marshes. These sediments can stimulate plant growth by providing nutrient and elevation subsidies, with plant growth predicted to peak at intermediate sediment depths. Most sediment subsidy studies have compared plant responses among discrete sediment depths applied across a uniform marsh platform, and often assessed impacts in the years following sediment deposition. Less is known about the immediate effects of sediment additions on plant growth or the mechanisms driving differences in these responses along a sediment-addition gradient. To investigate immediate plant responses to sediment additions (i.e., within 6 months), we added sediment to Schoenoplectus americanus -dominated brackish marsh sods in a greenhouse setting. Sediment was added incrementally along a sediment addition gradient (0–20 cm) to 18 sods, which were placed in clear planting enclosures to permit monitoring of above- and below-ground responses and hydro-edaphic properties. Shoot production, which increased linearly along the sediment addition gradient, was the first observable response to sediment addition and was likely a result of apical dominance interruption. This trend continued throughout the study even as survival of those shoots declined with increasing sediment depth. At the end of the experiment, however, shoot biomass production was biphasic, responding favorably to sediment addition up to intermediate depths before collapsing at higher depths. While fine root production in sods was maximal at intermediate sediment addition levels, root production in new sediment layers was limited. There were limited differences observed for hydro-edaphic properties along the sediment addition gradient. Thus, plant resources are allocated to shoot production immediately following sediment addition at the expense of root colonization of new sediment layers, suggesting that, in certain conditions, sediment deposition can represent a stress rather than a subsidy.

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USGS2019

Hydrodynamic controls on sediment retention in an emerging diversion-fed delta

The morphodynamics of river-dominated deltas are largely controlled by the supply and retention of sediment within deltaic wetlands and the rate of relative sea-level rise. Yet, sediment budgets for deltas are often poorly constrained. In the Mississippi River Delta, a system rapidly losing land due to natural and anthropogenic causes, restoration efforts seek to build new land through the use of river diversions. At the Davis Pond Freshwater Diversion, a new crevasse splay has emerged since construction was completed in 2002. Here, we use beryllium-7 activity in sediment cores and USGS measurements of discharge and turbidity to calculate seasonal sediment input, deposition, and retention within the vegetated Davis Pond receiving basin. In winter/spring 2015, which included an experimental period of high discharge through the diversion, Davis Pond received 106,800 metric tons of sediment, 44% of which was retained within the basin. During this time, mean flow velocity was 0.21 m s −1 and mean turbidity was 56 formazin nephelometric units (FNU). In summer/fall 2015, the Davis Pond basin received 35,900 metric tons of sediment, 81% of which was retained. Mean flow velocity in summer/fall was 0.10 m s −1 and mean turbidity was 55 FNU. The increase in sediment retention from winter/spring 2015 to summer/fall 2015 may be due in part to the corresponding drop in water flow velocity, which allowed more sediment to settle out of suspension. Although high water discharge increases sediment input and deposition, increased turbulence associated with higher current velocity appears to increase sediment throughput and thereby decrease the sediment trapping efficiency. Sediment retention in Davis Pond is on the high end of the range seen in deltaic wetlands, perhaps due to the enclosed geometry of the receiving basin. Future diversion design and operation should target moderate water discharge and flow velocities in order to jointly maximize sediment deposition and retention and provide optimal conditions for delta growth.

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USGS2019

High-Resolution mapping of biomass and distribution of marsh and forested wetlands in southeastern coastal Louisiana

This study estimates herbaceous and forested wetland coverage and aboveground biomass (AGB) within the Atchafalaya and Terrebonne coastal basins representing sediment rich and sediment poor coastal regions of southern Louisiana. Louisiana coastal wetlands account for approximately one third (37%) of the estuarine wetland area in the conterminous United States, yet the spatial distribution of their extent and aboveground biomass estimates are not well defined. Despite the importance of Louisiana’s coastal wetlands, existing maps on their extent are often outdated yet repeatedly used in national greenhouse gas (GHG) inventories and within regional aboveground biomass and carbon content estimates. Sentinel-2 optical satellite data was used within an object-oriented machine learning approach to classify wetland extent, mapping the spatial distribution of the coastal wetlands at high-resolution. A total wetland extent of 2950 km2 was mapped during a period of peak biomass in September 2017, comprised of forested and herbaceous wetlands (accuracy >90%) and demonstrated considerable differences (793.7 km2) from currently available estimates of wetland area. The distribution of aboveground biomass (AGB) was mapped using class averaged values derived from field data collected during May and September 2015. Total herbaceous biomass at the study site increased by 108.9% from May (668,684.5 Mg) to September (1,396,969.2 Mg) whilst the total woody vegetation biomass (27,667,232.1 Mg) was sampled in May only. This method provides a tractable means of mapping wetland extent and biomass, in a region threatened with wetland loss under projections of increasing sea-level rise and local subsidence.

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USGS2019

Application of sediment end-member analysis for understanding sediment fluxes, northern Chandeleur Islands, Louisiana

We analyzed grain-size distributions (GSDs) from a time-series of sediment samples to evaluate sediment transport following anthropogenic sand-berm emplacement at the northern Chandeleur Islands, Louisiana. End-member analysis (EMA) was applied to compare the end-member (EM) GSD of a known sediment source to GSDs from surrounding environments and characterize the physical redistribution of source sediment over time. Although we successfully modeled a proxy borrow-source EM using pre-emplacement (2007-2008) datasets, this EM is not easily distinguishable from the modeled emergent-island EM, possibly because the baseline dataset did not provide the necessary sample distribution to distinguish the range of depositional environments. Comparison of post-emplacement (2012) samples from the berm and natural island with the proxy borrow-source EM suggests that this application of EMA can be a valuable tool for understanding sediment redistribution subsequent to restoration efforts, especially if the GSDs of the emplaced and naturally-occurring sediments are dissimilar and adequately sampled.

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