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At least 19 recordsLinked to original sources

U.S. Geological Survey Mississippi River Science Forum—Summary of data and science needs and next steps

The U.S. Geological Survey hosted a Mississippi River Science Forum with Federal agencies; Tribal, State, and local governments located in States that border the Mississippi River; academia; and other interested stakeholders. The purpose of the forum was to share current (2023) science; identify data gaps and areas of concern; and to prioritize next steps needed to advance the goals of improving water quality, restoring habitat and natural systems, improving navigation, eliminating aquatic invasive species, and building local resilience to natural disasters along the Mississippi River. The forum was a directive for the U.S. Geological Survey in the Consolidated Appropriations Act of 2022 (Public Law 117—103, 136 Stat. 49). Participants and stakeholders that attended the Mississippi River Science Forum indicated the following. A Mississippi River Science Committee could bring together the voices of all stakeholders, including Federal agencies; State, local, and Tribal governments; academia; nongovernmental organizations; business and industry; and other interested parties. This committee would also work with (but not replace) Mississippi River Basin entities already in place and establish effective communication to identify and address Basin-wide management needs and to develop holistic solutions for those needs. A Mississippi River science plan could expand on the science and data gaps identified by the Forum. This plan could guide data collection and help resource managers develop and implement restoration initiatives within the Basin, recognizing that addressing these needs will require substantial resources. The science committee, working with other entities in the basin, should develop data standards for the Mississippi River Basin that allow stakeholders to utilize comparable data to address their needs. These standards would include data findability, accessibility, interoperability, and reusability. This report highlights data gaps and areas of concern discussed during the forum, and it identifies needs to advance the goals of improving water quality, restoring habitat and natural systems, improving navigation, eliminating aquatic invasive species, and building local resilience to natural disasters with specific emphasis on data collection and measurement, and scientific investigation. The report also summarizes stakeholder input and feedback and outlines next steps identified by forum participants.

Open-File Report↗

Recent subsidence-rate reductions in the Mississippi Delta and their geological implications

The Mississippi Delta has long been characterized as an area of rapid subsidence; however, recent subsidence rates are substantially lower than previously reported. Tide-gauge records indicate that rates of relative sea-level rise were slow from 1947 until the mid-1960s, relatively fast from the mid-1960s until the early 1990s, and then slow since the early 1990s. These trends and rates are independently verified by repeat benchmark surveys and height monitoring at continuously operating geographic positioning system stations. Subsidence rates for the slow periods were a few millimeters per year, comparable to rates averaged over geological time scales that are attributed to natural processes such as shallow sediment compaction and deep crustal loading. The decadal pattern of slow, then rapid, then slow subsidence may be caused by natural deep-basin processes ( e.g., gravity gliding and salt migration), but it is more likely related to rates of hydrocarbon production that followed the same temporal trends. If accelerated subsidence was primarily induced by reservoir compaction and fault reactivation associated with fluid withdrawal that also accelerated in the 1960s and 1970s, then the recent reductions in subsidence rates likely reflect a balancing of subsurface stresses and a return to near preproduction conditions.

Arkansas, Louisiana, Mississippi↗

Watershed Boundary Dataset for Mississippi

The U.S. Geological Survey, in cooperation with the Mississippi Department of Environmental Quality, U.S. Department of Agriculture-Natural Resources Conservation Service, Mississippi Department of Transportation, U.S. Department of Agriculture-Forest Service, and the Mississippi Automated Resource Information System developed a 1:24,000-scale Watershed Boundary Dataset for Mississippi including watershed and subwatershed boundaries, codes, names, and areas. The Watershed Boundary Dataset for Mississippi provides a standard geographical framework for water-resources and selected land-resources planning. The original 8-digit subbasins (Hydrologic Unit Codes) were further subdivided into 10-digit watersheds (62.5 to 391 square miles (mi2)) and 12-digit subwatersheds (15.6 to 62.5 mi2) - the exceptions being the Delta part of Mississippi and the Mississippi River inside levees, which were subdivided into 10-digit watersheds only. Also, large water bodies in the Mississippi Sound along the coast were not delineated as small as a typical 12-digit subwatershed. All of the data - including watershed and subwatershed boundaries, subdivision codes and names, and drainage-area data - are stored in a Geographic Information System database, which are available at: http://ms.water.usgs.gov/. This map shows information on drainage and hydrography in the form of U.S. Geological Survey hydrologic unit boundaries for water-resource 2-digit regions, 4-digit subregions, 6-digit basins (formerly called accounting units), 8-digit subbasins (formerly called cataloging units), 10-digit watershed, and 12-digit subwatersheds in Mississippi. A description of the project study area, methods used in the development of watershed and subwatershed boundaries for Mississippi, and results are presented in Wilson and others (2008). The data presented in this map and by Wilson and others (2008) supersede the data presented for Mississippi by Seaber and others (1987) and U.S. Geological Survey (1977).

Scientific Investigations Map↗

Shallow geologic framework of the Mississippi Sound and the potential for sediment resources

The Mississippi Sound, an estuarine environment located between the mainland and barrier islands bordering the northern Gulf of America (formerly the Gulf of Mexico), serves as a vital ecosystem for the States of Mississippi and Alabama. Spanning approximately 100 kilometers from east to west and covering 1,400 square kilometers, the sound is home to marine industry and ports, and its shallow and brackish waters sustain a diverse array of marine life. Barrier islands along the southern edge of the sound separate the microtidal estuary from the Gulf of America. This protection from gulf wave action mediates current flow within the sound, resulting in predominantly fine-grained sediment deposition along the seafloor. This study, conducted by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers, provides insight on fluvial and tidal processes spanning the past 5,000 years. The report synthesizes existing research to provide a comprehensive overview of the sound geology, from Pleistocene origins to present-day morphology, and utilizes high-resolution single channel seismic profiles and sediment data to identify and map sedimentary deposits and morphologic features at and below the seafloor. Despite its ecological significance, the Mississippi Sound faces environmental challenges, including water-quality issues, habitat degradation, storm-induced erosion, and the ongoing threats of sea-level rise and environmental changes. This study uses the present-day understanding of the sound's geology to inform coastal management decisions, hazard assessment, and potential mineral resources.

Louisiana, Mississippi↗

Development of a Watershed Boundary Dataset for Mississippi

The U.S. Geological Survey, in cooperation with the Mississippi Department of Environmental Quality, U.S. Department of Agriculture-Natural Resources Conservation Service, Mississippi Department of Transportation, U.S. Department of Agriculture-Forest Service, and the Mississippi Automated Resource Information System, developed a 1:24,000-scale Watershed Boundary Dataset for Mississippi including watershed and subwatershed boundaries, codes, names, and drainage areas. The Watershed Boundary Dataset for Mississippi provides a standard geographical framework for water-resources and selected land-resources planning. The original 8-digit subbasins (hydrologic unit codes) were further subdivided into 10-digit watersheds and 12-digit subwatersheds - the exceptions are the Lower Mississippi River Alluvial Plain (known locally as the Delta) and the Mississippi River inside levees, which were only subdivided into 10-digit watersheds. Also, large water bodies in the Mississippi Sound along the coast were not delineated as small as a typical 12-digit subwatershed. All of the data - including watershed and subwatershed boundaries, hydrologic unit codes and names, and drainage-area data - are stored in a Geographic Information System database.

Open-File Report↗

The Geology of the Upper Mississippi Valley Zinc-Lead District

The upper Mississippi Valley zinc-lead district includes the southwest part of Wisconsin, the northwest corner of Illinois, and a narrow fringe of Iowa extending from Bellevue to McGregor, just west of the Mississippi River. The total area of the district is 4,000 square miles. The entire district is drained by the Mississippi River and its tributaries. The central part is a rolling plain dissected to a depth of about 300 feet by the larger stream valleys. Marginal parts of the district are relatively hilly. Most of the district lies within the so-called "Driftless Area", but glacial deposits occur in the eastern, southeastern, and western fringes of the district.

Illinois, Iowa, Wisconsin↗

Comparison of flood frequency estimates from synthetic and observed data on small drainage areas in Mississippi

In 1964 the U.S. Geological Survey in Mississippi expanded the small stream gaging network for collection of rainfall and runoff data to 92 stations. To expedite availability of flood frequency information a rainfall-runoff model using available long-term rainfall data was calibrated to synthesize flood peaks. Results obtained from observed annual peak flow data for 51 sites having 16 yr to 30 yr of annual peaks are compared with the synthetic results. Graphical comparison of the 2, 5, 10, 25, 50, and 100-year flood discharges indicate good agreement. The root mean square error ranges from 27% to 38% and the synthetic record bias from -9% to -18% in comparison with the observed record. The reduced variance in the synthetic results is attributed to use of only four long-term rainfall records and model limitations. The root mean square error and bias is within the accuracy considered to be satisfactory. (Author 's abstract)

Water-Resources Investigations Report↗

Background hydrologic information in potential lignite mining areas in Mississippi, August 1980

The U.S. Geological Survey in cooperation with Mississippi Bureau of Geology is conducting a hydrologic data-collection program in the potential lignite-producing areas in Mississippi. During the week of August 25-28, 1980, hydrologic data on channel characteristics were collected at 15 sites on small streams draining potential lignite mining areas in east-central Mississippi. Streamflow measurements were made and water-quality samples were collected at 11 of the 15 sites. Main channel widths at the 15 sampling sites in east-central Mississippi ranged from 126 feet on Sucarnoochee Creek to 15 feet on Houston Creek. Maximum water depth ranged from 7 feet on Pawticfaw Creek and Tallahatta Creek to one-half foot on Okatibbee Creek. The maximum stream discharge measured was 56 cubic feet per second on Pawticfaw Creek. Four sites had no discharge. Specific conductance at sampling sites ranged from 115 micromhos on Ponta Creek to 26 micromhos on Sucarnoochee Creek. The dissolved-oxygen concentration was 5.7 milligrams per liter or higher at all sites. The concentration of suspended sediment was not greater than 38 milligrams per liter at any site. Concentrations of calcium, magnesium, sodium, potassium, chloride, and sulfate were less than 10 milligrams per liter in all samples, but were highest at site 10 on Ponta Creek. Bottom-material samples commonly contained iron, manganese, and zinc.

Mississippi↗

Water quality monitoring and data collection in the Mississippi sound

The United States Geological Survey and the Mississippi Department of Marine Resources are collecting data on the quality of the water in the Mississippi Sound of the Gulf of Mexico, and streamflow data for its tributaries. The U.S. Geological Survey is collecting continuous water -level data , continuous and discrete water -temperature data , continuous and discrete specific-conductance data , as well as chloride and salinity samples at two locations in the Mississippi Sound and three Corps of Engineers tidal gages. Continuous-discharge data are also being collected at two additional stations on tributaries. The Mississippi Department of Marine Resources collects water samples at 169 locations in the Gulf of Mexico. Between 1800 and 2000 samples are collected annually which are analyzed for turbidity and fecal coliform bacteria. The continuous data are made available real-time through the internet and are being used in conjunction with streamflow data , weather data , and sampling data for the monitoring and management of the oyster reefs, the shrimp fishery and other marine species and their habitats.

Conference Paper↗

Refining the link between the Holocene development of the Mississippi River Delta and the geologic evolution of Cat Island, MS: implications for delta-associated barrier islands

The geologic evolution of barrier islands is profoundly influenced by the nature of the deposits underlying them. Many researchers have speculated on the origin and evolution of Cat Island in Mississippi, but uncertainty remains about whether or not the island is underlain completely or in part by deposits associated with the past growth of the Mississippi River delta. In part, this is due to a lack of comprehensive geological information offshore of the island that could augment previous stratigraphic interpretations based on terrestrial borings. An extensive survey of Cat Island and its surrounding waters was conducted, including shallow-water geophysics (e.g., high-resolution chirp seismic, side-scan sonar, and swath and single-beam bathymetry) and both terrestrial and marine vibracoring. High-resolution seismic data and vibracores from south and east of the island show two horizontally laminated silt units; marine radiocarbon dates indicate that they are St. Bernard delta complex (SBDC) deposits. Furthermore, seismic data reveal that the SBDC deposits taper off toward the southern shoreline of Cat Island and to the west, morphology consistent with the distal edge of a delta complex. The sedimentology and extent of each unit suggest that the lower unit may have been deposited during an earlier period of continuous river flow while the upper unit may represent reduced or sporadic river flow. OSL dates from the island platform (beneath beach ridge complexes) indicate three stages of terrestrial evolution: island emergence resulting from relative sea-level rise (~ 5400 ybp) island aggradation via littoral transport (~ 2500–4000 ybp) and island degradation due to delta-mediated changes in wave direction (present– ~ 3600 ybp). Finally, the combination of terrestrial and marine data shows that portions of Cat Island that are lower in elevation than the central part of the island are younger and are likely underlain by a thin layer of deltaic sediments. This underscores the potential for increased future vulnerability of barrier islands that develop adjacent to major river delta complexes.

Mississippi↗