{"accessLevel": "public", "bureauCode": ["010:12"], "contactPoint": {"@type": "vcard:Contact", "fn": "Scott T. Prinos", "hasEmail": "mailto:stprinos@usgs.gov"}, "description": "Time series electromagnetic-induction log (TSEMIL) datasets are collected from PVC cased or uncased \nmonitoring wells to evaluate changes in water conductivity over time.\nTSEMIL datasets consist of a series of individual electromagnetic-induction logs collected at a\nfrequency of months or years that have been compiled into a dataset by eliminating small\nuniform offsets in bulk conductivity between logs likely caused by minor variations in\ncalibration. At depths where water conductivity is not changing through time, each log is\ntypically within about \u00b115 mS/m of the median of the dataset at any given depth, which is\nwithin the stated resolution, repeatability, and accuracy specifications of the probe. Though the\noffsets between logs are small (\u00b115 mS/m), they obscure the ability to identify small but real\nchanges in bulk conductivity resulting from changes in aquifer salinity. These offsets are\nremoved by selecting a depth at which no changes are apparent from year to year, and by\nadjusting individual logs to the median of all logs at the selected depth. Generally, these\ndepths are within the freshwater saturated part of the aquifer, well below the water table. Once\nthe offsets have been removed there is generally only about \u00b12 mS/m of completely irregular\nvariation between successive logs that cannot be removed. Even if perfect numerical\nalignment is achieved at one or two depths, the \u00b12 mS/m of random variation remains at other\ndepths. Given these corrections, however, changes from year to year caused by saltwater\nintrusion are easier to identify. Detailed descriptions of how these corrections are applied are\ndescribed in Prinos and others (2014) and Prinos and Valderrama (2015).\nTSEMIL datasets can be used to monitor changes in water conductivity throughout the full thickness of an aquifer, \nwithout the need for long open-interval wells, which have, in some\ninstances, allowed vertical water flow within the well bore that has biased water conductivity\nprofiles (Prinos and Valderrama, 2015). Although TSEMIL datasets are most commonly used\nto evaluate saltwater intrusion some other observed changes evident in TSEMIL datasets are:\n(1) variations in bulk conductivity near the water table where water saturation of pore spaces\nmay vary, and water temperature may be more variable, (2) dissipation of conductive water in\nhigh porosity rock layers, which may have entered these layers during drilling.", "distribution": [{"@type": "dcat:Distribution", "accessURL": "http://dx.doi.org/10.5066/F7NV9GBT", "description": "Landing page for access to the data", "format": "XML", "mediaType": "application/http", "title": "Digital Data"}, {"@type": "dcat:Distribution", "description": "The metadata original format", "downloadURL": "https://data.usgs.gov/datacatalog/metadata/USGS.56abd635e4b0403299f46586.xml", "format": "XML", "mediaType": "text/xml", "title": "Original Metadata"}], "identifier": "http://datainventory.doi.gov/id/dataset/USGS_56abd635e4b0403299f46586", "keyword": ["Biscayne Bay", "Biscayne aquifer", "Broward County", "Bulk conductivity", "Florida", "Geophysical", "Glades County", "Hendry County", "Induction", "Lake Okeechobee", "Miami-Dade County", "North America", "Palm Beach County", "Surficial Aquifer System", "TSEMIL datasets", "Time series electromagnetic induction-log datasets", "USGS:56abd635e4b0403299f46586", "Well logs"], "modified": "2020-08-12T00:00:00Z", "publisher": {"@type": "org:Organization", "name": "U.S. Geological Survey"}, "spatial": "-82.5, 24.5, -80.0, 27.5", "theme": ["geospatial"], "title": "Time Series Electromagnetic Induction-Log Datasets, Including Logs Collected through the 2014 Water Year in South Florida"}