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Research about Louisiana

Source-linked reports with geographic coverage including Louisiana.

At least 613 records · Page 34Linked to original sources
USGS2002

Louisiana ground-water map no. 13: Hydrogeology and potentiometric surface of the Sparta aquifer in northern Louisiana, October 1996

This report describes the thickness and areal extent of the Sparta aquifer, identifies sands within the fresh-water extent of the aquifer, and presents data and a map that illustrate the generalized potentiometric surface (water levels) during October 1996. The report includes a detailed geophysical log, structure contour maps, hydrogeologic sections, and hydrographs of water levels in selected wells. The potentiometric surface-map can be used for determining direction of ground-water flow, hydraulic gradients, and the effects of withdrawals on the aquifer.

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USGS2002

Effects of ENSO on weather-type frequencies and properties at New Orleans, Louisiana, USA

Examination of historical climate records indicates a significant relation between the El Nino/Southern Oscillation (ENSO) and seasonal temperature and precipitation in Louisiana. In this study, a 40 yr record of twice daily (06:00 and 15:00 h local time) weather types are used to study the effects of ENSO variability on the local climate at New Orleans, Louisiana. Tropical Pacific sea-surface temperatures (SSTs) for the NINO3.4 region are used to define ENSO events (i.e. El Nino and La Nina events), and daily precipitation and temperature data for New Orleans are used to define weather-type precipitation and temperature properties. Data for winters (December through February) 1962-2000 are analyzed. The 39 winters are divided into 3 categories; winters with NINO3.4 SST anomalies < -1degreesC (La Nina events), winters with NINO3.4 anomalies > 1degreesC (El Nino events), and neutral conditions (all other years). For each category, weather-type frequencies and properties (i.e. precipitation and temperature) are determined and analyzed. Results indicate that El Nino events primarily affect precipitation characteristics of weather types at New Orleans, whereas the effects of La Nina events are most apparent in weather-type frequencies. During El Nino events, precipitation for some of the weather types is greater than during neutral and La Nina conditions and is related to increased water vapor transport from the Tropics to the Gulf of Mexico. The changes in weather-type frequencies during La Nina events are indicative of a northward shift in storm tracks and/or a decrease in storm frequency in southern Louisiana.

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USGS2002

Sediment-hosted contaminants and distribution patterns in the Mississippi and Atchafalaya River Deltas

The Mississippi and Atchafalaya Rivers transport very large amounts of bedload and suspended sediments to the deltaic and coastal environments of the northern Gulf of Mexico. Absorbed onto these sediments are contaminants that may be detrimental to the environment. To adequately assess the impact of these contaminants it is first necessary to develop an understanding of sediment distribution patterns in these deltaic systems. The distribution patterns are defined by deltaic progradational cycles. Once these patterns are identified, the natural and industrial contaminant inventories and their depositional histories can be reconstructed. Delta progradation is a function of sediment discharge, as well as channel and receiving-basin dimensions. Fluvial energy controls the sediment distribution pattern, resulting in a coarse grained or sandy framework, infilled with finer grained material occupying the overbank, interdistributary bays, wetlands and abandoned channels. It has been shown that these fine-grained sediments can carry contaminants through absorption and intern them in the sediment column or redistribute them depending on progradation or degradation of the delta deposit. Sediment distribution patterns in delta complexes can be determined through high-resolution geophysical surveys and groundtruthed with direct sampling. In the Atchafalaya and Mississippi deltas, remote sensing using High-Resolution Single-Channel Seismic Profiling (HRSP) and Sidescan Sonar was correlated to 20-ft vibracores to develop a near-surface geologic framework that identifies variability in recent sediment distribution patterns. The surveys identified bedload sand waves, abandoned-channel back-fill, prodelta and distributary mouth bars within the most recently active portions of the deltas. These depositional features respond to changes in deltaic processes and through their response may intern or transport absorbed contaminants. Characterizing these features provides insight into the fate of sediment-hosted contaminants.

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USGS2002

Sand resources, regional geology, and coastal processes for shoreline restoration: case study of Barataria shoreline, Louisiana

The Louisiana barrier shoreline of Barataria Basin, which lies within the western Mississippi River delta, has undergone significant retreat during the past 100 years. The most practical restoration method to rebuild these shorelines is sand nourishment. Seismic and sonar interpretations verified with geologic samples (vibracores and borings) indicate that there are nine sand targets within the Barataria study area that meet or exceed the minimum criteria for potential resource sites. However, the near surface lithology in the basin is typically silts and clays. Locating suitable sand resources for shoreline restoration is challenging. The sand units are associated with geologic depositional systems such as ebb-tidal deltas, distributary mouth bars, and channel fill (undifferentiated fluvial or tidal inlet channels). The nine potential sand targets consist primarily of fine sand and can be delineated into three surficial and six buried features. The surficial features contain approximately 10% of the total sand resources identified. At least 90% of the sand resources need overburden sediment removed prior to use; almost 570 million yd 3 (438.5 mil m 3 ) of overburden will need to be removed if the entire resource is mined. In this study, we identified 396 to 532 mil yd 3 (305.8 to 410.8 mil m 3 ) of potential sand deposits for shoreline restoration. Previous studies using less dense survey methods greatly over-estimated sand resources available in this area. Many fluvial channels reported previously as sand-filled are mud-filled. Contrary to these previous studies, few fluvial subsystems in this region have abundant sand resources.

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USGS2002

Latest Quaternary stratigraphic framework of the Mississippi River delta region

Previous researchers separated the uppermost Quaternary stratigraphy of the Mississippi River delta region into two major lithofacies. The stratigraphically lower of these, "substratum," primarily consists of coarse-grained sediment deposited within lowstand-incised stream valleys. Relatively finer-grained "topstratum" overlies substratum; above interfluves, topstratum directly overlies weathered late Pleistocene sediments. However, the onshore to offshore distribution and architecture of these lithofacies was not well constrained. This study integrates published and unpublished lithostratigraphic data with high-resolution seismic profiles from the continental shelf to aid in mapping the regional distribution of major substratum deposits and thickness of topstratum sediments. A transgressive sand sheet commonly marks the base of the topstratum deposits, providing a stratigraphic marker to aid in regional lithostratigraphic correlations. Radiocarbondated deposits and boreholes tied to oxygen isotope chronologies provide chronostratigraphic control. Excellent correlation between these multiple datasets has been found to exist, enabling construction of regional isopachous and structural elevation maps and cross sections detailing elements of the Late Quaternary stratigraphy.

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USGS2002

Subsurface controls on historical subsidence rates and associated wetland loss in southcentral Louisiana

Two regional releveling profiles and six tide gauges provide a basis for evaluating recent rates of delta plain subsidence in southcentral Louisiana . Analyses of these records demonstrate close correlations among highest historical rates of subsidence , rapid wetland losses, large volume hydrocarbon production, and probable reactivation of deep subsurface faults. Other researchers have demonstrated that the highest geological subsidence rates of the Mississippi delta plain (<3 mm/yr) correspond closely to the thickest Holocene sediments that fill the underlying incised valley. Within that geologic framework, highest historical subsidence rates (as much as 23 mm/yr) correspond to surface projections of the reactivated Lake Hatch and Golden Meadow fault zones and to individual oil and gas fields. The initial acceleration and subsequent decline in rates of wetland loss in southcentral Louisiana are attributed partly to increased and then possibly decreased rates of subsidence that were related to increased and then decreased rates of fluid production. Decreases in subsurface pore pressures associated with gas production were so large that the state of stress was altered and critically stressed faults were likely reactivated. Subsidence rates in coastal Louisiana associated with natural compaction and dewatering of Holocene deltaic sediments should decrease with time. Therefore historical rates of delta plain subsidence that accelerate and typically exceed geological subsidence rates are most likely influenced by anthropogenic activities, such as subsurface fluid extraction.

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USGS2002

Water withdrawals and trends in ground-water levels and stream discharge in Louisiana

In 2000, approximately 10,400 mgal/ d (million gallons per day) of water was withdrawn from ground - and surface- water sources in Louisiana , an increase of 10 percent from 1990. In 2000, about 16 percent (1,600 Mgal/ d ) of the water withdrawn was ground water . Approximately 93 percent of the ground water withdrawn was from four aquifers or aquifer systems: the Chicot aquifer system (49 percent), the Mississippi River alluvial aquifer (22 percent), the Sparta aquifer (4 percent), and the Southern Hills aquifer system (18 percent). Three of these, the Chicot aquifer system, the Sparta aquifer, and the Southern Hills aquifer system, contain areas where declines in ground - water levels from 1990-2000 are 1 ft/yr (foot per year) or greater. The Chicot aquifer system in southwestern Louisiana is the most heavily pumped aquifer or aquifer system in the State. By 2000, water levels in areas of Calcasieu, Jefferson Davis, and Acadia Parishes had declined to 50 feet or more below sea level. Water levels in areas of largest withdrawals declined as much as 1.7 ft/yr during the period 1990-2000. The Sparta aquifer in north-central Louisiana is the fourth most heavily pumped aquifer in the State. Approximately 68.2 Mgal/d was withdrawn in 2000. Water levels in the aquifer declined to more than 200 feet below sea level in the Monroe area by 1997. During 1990-2000, water level declines ranged from 0.1 to 5.2 ft/yr at monitor wells screened in the aquifer. The Southern Hills aquifer system of southeastern Louisiana is composed of numerous freshwater aquifers. This aquifer system is the third most heavily pumped aquifer or aquifer system in the State (291 Mgal/d in 2000). By the 1970's saltwater encroachment had been documented in major aquifers in the Baton Rouge area. Water levels in deep aquifers having largest withdrawals declined about 0.2 to 3.5 ft/yr or more during the period 1990-2000. In 2000, about 84 percent (8,700 Mgal/d) of the water withdrawn in Louisiana was surface water. Stream discharge data were analyzed for 59 continuous discharge stations. Eleven stations on nine streams had decreasing mean annual discharge during the period 1990-2000.

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USGS2002

Managing agricultural wetlands for waterbirds in the coastal regions of Louisiana, U.S.A.

Rice and/or crawfish are cultivated in over 225,000 ha of shallow earthen impoundments within 160 km of the Gulf of Mexico along the coast of Louisiana. The region includes both the Gulf Coastal Plain and Prairie and the Lower Mississippi River Valley. Annual loss of 4,475 ha of coastal wetlands in Louisiana due to subsidence, erosion, and rising sea level has significantly reduced desirable freshwater habitat in the region. The suite of resident, migrant, breeding, and wintering waterbirds depending on this region includes grebes, pelicans, cormorants, anhingas, wading birds, waterfowl, coots, rails, gallinules, shorebirds, gulls, terns, and kingfishers. These taxa utilize the artificial freshwater wetland habitat provided by the agricultural wetlands. Numerous other birds utilize riparian areas associated with these artificial wetlands. Crawfish ponds are especially valuable cool season habitat for predaceous waterbirds because they provide shallow water systems rich in invertebrate and small vertebrate prey during the period from mid-autumn through mid-spring when most rice fields are drained. Because most crawfish ponds are not drained until late spring or early summer, predictable, food-rich, shallow water waterbird habitat is available throughout the region when rice fields are being cultivated for rice production. Incorporation of crawfish management into government-sponsored land conservation programs should encourage land owners to sustain standing water habitat outside of program mandated fill/drain requirements. Farmers could adjust the times when their impoundments are filled or drained to maximize benefits to many species, especially migrating shorebirds.

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USGS2001

Patterns and processes of wetland loss in coastal Louisiana are complex: A reply to Turner 2001. Estimating the indirect effects of hydrologic change on wetland loss: If the Earth is curved, then how would we know it?

The coastal wetlands of Louisiana comprise a vast expanse of marine to freshwater wetland plant communities interspersed w-ith shallow bays and bayous. These wetlands were built by processes associated with the present-day Mississippi and Atchatfalaya River deltas and older distributaries occupied by the river over the past 7,000 }rears. The high rates of wetland loss identified in this system during the 20th century have serious consequences for living resources (Boesch et al. 1994) and coastal residents, and they affect our ability to maintain navigation and flood control. The restoration and management response to this problem must be grounded in a sound understanding of the causative factors. The system has been highly altered by river levees, roads and railway embankments, impoundments, and canals of many dimensions dredged for a variety of purposes. These changes have been imposed on a landscape that is essentially the result of a delicate natural balance between wetland building processes and compaction, subsidence, and sea-level rise. Many now recognize that coastal wetlands can cope with relatively high rates of subsidence and sea-level rise, as long as the processes that ensure wetland sustainability through vertical accumulation of substrate remain unimpaired (Boesch et al. 2000). The challenge facing both the scientific community and coastal resource managers in Louisiana is to look to the future. We must use our understanding of the problem and how it evolved to develop a multi-use ecosystem management plan, and some efforts have been made by state and federal agencies towards this goal (LCWCRTF & WCRA 1998). The present discussions (Turner 1997, 2001; Day et al. 2000; Gosselink 2001) demonstrate the complexity of the issues faced in Louisiana. While such discourse is common in the scientific community where varied approaches and interpretations are a sign of vitality, it is helpful to be clear about the state of knowledge and what levels of uncertainty exist. We seek to clarify some of the issues that have been raised in the discussion, recognizing that our best-available science cannot yet resolve many of them as completely as all would like.

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USGS2001

Water resources data, Louisiana, water year 2000

Water resources data for the 2000 water year for Louisiana consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 66 gaging stations; stage only for 70 gaging stations and 7 lakes; water quality for 45 surface-water stations (including 25 gaging stations) and 108 wells; and water levels for 221 observation wells. Also included are data for 204 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not included in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.

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USGS2001

Hydrogeologic framework and potentiometric surface of the Williamson Creek Aquifer "B" sand in the Fort Polk area, Vernon Parish, Louisiana, March 1997

The Fort Polk Military Reservation(hereinafter referred to as the Reservation) in Vernon Parish, Louisiana, occupies 107,024 acres of lands; 66,998 acres are owned by the U.S. Army, and 40,026 acres are owned by the U.S. Forest Service (Dan Nance, Fort Polk Public Affairs office, written commun., 1998). Some areas of the Reservation, such as an artillery impact area, live-firm areas, and special purpose training areas, are restricted to military personnel. The Williamson Creek and Carnahan Bayou aquifers are major sources of freshwater for the Reservation. IN 1996, the Reservation's total water pumpage from the Williamson Creek aquifer for public supply was approxiamately 2.4 million gallons per day (Edward Ducote, Water and Wastewater Branch, Directorate of Public Works, Fort Polk, written commun., 1998). In 1997, the water withdrawl rate for public supply was approzimately 1.88 million gallons per day from 11 wells completed in the Williamson Creek aquifer. Almost all of the water was withdrawn from the "B" sand, which is the predominant sand layer of the Williamson Creek aquifer in the study area. In 1997, nearby Leesville, the seat of Vernon Parish, withdrew all its water for public supply from the deeper Carnahan Bayou aquifer.

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USGS2001

Coastal change analysis program implemented in Louisiana

Landsat Thematic Mapper images from 1990 to 1996 and collateral data sources were used to classify the land cover of the Mermentau River Basin (MRB) within the Chenier Plain of coastal Louisiana. Landcover classes followed the definition of the National Oceanic and Atmospheric Administration's Coastal Change Analysis Program; however, classification methods had to be developed as part of this study for attainment of these national classification standards. Classification method developments were especially important when classes were spectrally inseparable, when classes were part of spatial and spectral continuums, when the spatial resolution of the sensor included more than one landcover type, and when human activities caused abnormal transitions in the landscape. Most classification problems were overcome by using one or a combination of techniques, such as separating the MRB into subregions of commonality, applying masks to specific land mixtures, and highlighting class transitions between years that were highly unlikely. Overall, 1990, 1993, and 1996 classification accuracy percentages (associated kappa statistics) were 80% (0.79), 78% (0.76), and 86% (0.84), respectively. Most classification errors were associated with confusion between managed (cultivated land) and unmanaged grassland classes; scrub shrub, grasslands and forest classes; water, unconsolidated shore and bare land classes; and especially in 1993, between water and floating vegetation classes. Combining cultivated land and grassland classes and water and floating vegetation classes into single classes accuracies for 1990, 1993, and 1996 increased to 82%, 83%, and 90%, respectively. To improve the interpretation of landcover change, three indicators of landcover class stability were formulated. Location stability was defined as the percentage of a landcover class that remained as the same class in the same location at the beginning and the end of the monitoring period. Residence stability was defined as the percent change in each class within the entire MRB during the monitoring period. Turnover was defined as the addition of other landcover classes to the target landcover class during the defined monitoring period. These indicators allowed quick assessment of the dynamic nature of landcover classes, both in reference to a spatial location and to retaining their presence throughout the MRB. Examining the landcover changes between 1990 to 1993 and 1993 to 1996, led us to five principal findings: (1) Landcover turnover is maintaining a near stable logging cycle, although the locations of grassland, scrub shrub, and forest areas involved in the cycle appeared to change. (2) Planting of seedlings is critical to maintaining cycle stability. (3) Logging activities tend to replace woody land mixed forests with woody land evergreen forests. (4) Wetland estuarine marshes are expanding slightly. (5) Wetland palustrine marshes and mature forested wetlands in the MRB are relatively stable.

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