Concept information
Preferred term
NEI
Definition
- The National Estuarine Inventory is administered by ORCA's Strategic Environmental Assessment (SEA) Division. In addition to the assessment activities identified in the profiles that follow, the NEI is supported by the National Coastal Wetlands Inventory, the Estuarine Living Marine Resources Program, the National Shellfish Register, the Coastal and Ocean Resource Economics Program, the Coastal Development Trends Series, and the National Coastal Pollution Discharge Inventory. These projects and associated data holdings are described elsewhere in this report. The National Estuarine Inventory is a series of inter-related activities that define, characterize, and assess the Nation's estuarine systems. The goal of the NEI is to develop a comprehensive framework for evaluating the health and status of the Nation's estuaries and to bring estuaries into focus as a national resource base. NEI data are compiled in a systematic and consistent manner that enables the Nation's estuaries to be compared and assessed according to their environmental quality, economic values, and resource uses. The main holdings of the NEI project are described by the data set entries keyed to Campaign/Project NEI. This is supplemented by the following summaries of four databases: o Physical and Hydrologic Characteristics of Estuaries o Estuarine Land-Use Categories o Susceptibility of Estuaries to Nutrient Related Pollution o The National Estuarine Eutrophication Project Physical and Hydrologic Characteristics A principal feature of the NEI is the determination of the physical dimensions and hydrologic features of estuarine systems of the United States. These data are compiled in a consistent manner to allow users to distinguish the similarities and differences among individual estuaries or groups of estuaries. The physical characteristics of an estuary are primary determinants of estuarine processes and ultimately affect the ecology of a system. The principal physical parameter for which data are compiled is the Estuarine Drainage Area (EDA). Other dimensional parameters include the estuary length, width, and depth; the fluvial drainage area, or FDA (the land and water portion of the entire watershed upstream of the EDA); and the estuarine water surface area. The seaward boundary of each estuary is identified, and the estuary's length, area and volume is estimated for five salinity zones (from tidal fresh to seawater). Estimates are also generated for the average daily and monthly freshwater inflow (representing the streams discharging into the the entire drainage basin), tidal prism (the volume of water entering a coastal system during flood tide), and prevailing tide (diurnal or semidiurnal) for each estuary. Estuaries are classified according to degree of salinity stratification (highly stratified, moderately stratified, and vertically homogeneous classifications, reported for three-month periods). Estuarine Land-Use Categories The types of land use within an estuarine drainage basin indicate the overall extent to which human activities may affect the environmental quality of the basin and its waters. The NEI compiles information relating to the types of land uses within the drainage basins associated with major estuaries of the United States. When combined with information about other estuarine characteristics, land-use data may be used to assess the effects of various policies on the environmental quality of the Nation's estuarine resource base. The data base includes surface area estimates of seven categories and 24 subcategories of land uses in areas surrounding major estuaries. Categories include urban and built-up land (such as residential and industrial/commercial complexes), Agriculture, Range, Forest, Barren (such as beaches and dry salt flats), and Wetland land use types. Area estimates are compiled for three spatial units: (1) estuarine drainage areas (EDAs); (2) USGS cataloging units (the portion that falls within an EDA); and (3) counties that fall within or intersect EDAs (area estimates for the entire county). The data base encompasses 92 estuaries of the contiguous United States. Estimates are compiled for 92 EDAs, 216 USGS cataloging units, and 523 counties that fall within or intersect an EDA. The spatial resolution of the supporting data is 10 or 40 acres, depending on the land-use category. Land-use data were recorded between 1971 and 1984 and compiled during the mid-1980s. Susceptibility of Estuaries to Nutrient Discharges The NEI compiles data on the annual nutrient loads entering estuaries and the relative susceptibility of estuaries to nutrient-related pollution. These data allow water quality and resource managers to identify estuaries that are potentially at risk to nutrient loads and subsequently, to eutrophication conditions. Data relate to parameters that influence estuarine eutrophication, based on nutrient loading estimates and physical and hydrologic characteristics. Nutrient loading data include estimates of the total nitrogen and the total phosphorus discharged annually into estuaries from point, nonpoint, and upstream sources. The relative susceptibility of estuaries to nutrient pollution is quantified by the dissolved concentration potential (DCP), an estimate of the relative ability of an estuary to concentrate dissolved substances, such as nitrogen and phosphorus. This value characterizes the effect of flushing and estuarine dilution on pollutant loads. A classification scheme, indicating high, medium or low DCP values, is used to provide a relative ranking of estuaries in terms of their susceptibility to nutrient pollution. The level of nutrient pollution is identified by the estimated concentrations of nitrogen and phosphorus, a classification of those concentrations (high, medium and low concentrations), and an estimate of what percentage change (increase or decrease) in nutrient loadings would be required to change the nutrient concentration classifications. Additional data include the molecular ratio of nitrogen to phosphorus (N/P), which provides an estimate of which nutrient may be more influential in limiting phytoplankton production. The data encompass 82 estuaries identified in the NEI: 23 in the Northeast; 17 in the Southeast; 23 on the Gulf of Mexico; and 19 on the West coast. The data represent overall estuarine conditions, not site-specific conditions within an estuary Nutrient susceptibility studies were completed in 1990. Supporting physical and hydrologic data were generated primarily in the last decade. Loading estimates were derived from pollutant discharge data generated for the 1982 base year. Base-year estimates can be considered to approximate discharge conditions for a five-year period around the base year. The National Estuarine Eutrophication Project The National Estuarine Eutrophication Project is a data collection effort designed to quantify the degree and geographical extent of eutrophication in coastal estuaries, and to test the hypothesis that nutrient loads and eutrophic waters are linked. The Project expands upon related NEI studies, involving estuarine susceptibility to nutrient loadings (noted above), by assessing actual eutrophication problems and their characteristics. A goal of the Project is to develop a model linking nutrient loading concentrations and phytoplankton production to determine the probability of eutrophication conditions. Data will be collected on a variety of factors which characterize eutrophication conditions and effects. Hydrologic characteristics, such as water residence times and circulation patterns, determine the ability of an estuary to concentrate nutrient loads. The Project will examine such physical indicators as flushing, salinity, stratification, and tides. Data also will be collected on factors which express eutrophication effects, including: 1) water quality parameters, such as oxygen concentrations in bottom waters; nutrient concentrations; light penetration; turbidity; and 2) biological parameters, such as phytoplankton production (primary production); the appearance of nuisance seaweeds, algal blooms and floating algal scums; decreased submerged aquatic vegetation concentrations; benthic organism concentration and composition; bacterial activity; disease organisms (for marine populations); and secondary production (commercial harvests). The National Estuarine Eutrophication Project was initiated in 1991, however, supporting data may relate to environmental conditions recorded at earlier dates. Point of contact: Strategic Environmental Assessment Division Office of Ocean Resources Conservation and Assessment National Oceanic and Atmospheric Administration 6001 Executive Blvd Rockville, MD 20852 (en)
Broader concept
- M - O (en)
URI
https://gcmd.earthdata.nasa.gov/kms/concept/7a83d0fe-1932-4dbd-89bc-86a615886fa2
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