• Points for Maps: ArcGIS layer providing the site locations and the water-level statistics used for creating the water-level contour maps

    Metadata Updated: March 22, 2021

    Statistical analyses and maps representing mean, high, and low water-level conditions in the surface water and groundwater of Miami-Dade County were made by the U.S. Geological Survey, in cooperation with the Miami-Dade County Department of Regulatory and Economic Resources, to help inform decisions necessary for urban planning and development. Sixteen maps were created that show contours of (1) the mean of daily water levels at each site during October and May for the 2000-2009 water years; (2) the 25th, 50th, and 75th percentiles of the daily water levels at each site during October and May and for all months during 2000-2009; and (3) the differences between mean October and May water levels, as well as the differences in the percentiles of water levels for all months, between 1990-1999 and 2000-2009. The 80th, 90th, and 96th percentiles of the annual maximums of daily groundwater levels during 1974-2009 (a 35-year period) were computed to provide an indication of unusually high groundwater-level conditions. These maps and statistics provide a generalized understanding of the variations of water levels in the aquifer, rather than a survey of concurrent water levels. Water-level measurements from 473 sites in Miami-Dade County and surrounding counties were analyzed to generate statistical analyses. The monitored water levels included surface-water levels in canals and wetland areas and groundwater levels in the Biscayne aquifer. Maps were created by importing site coordinates, summary water-level statistics, and completeness of record statistics into a geographic information system, and by interpolating between water levels at monitoring sites in the canals and water levels along the coastline. Raster surfaces were created from these data by using the triangular irregular network interpolation method. The raster surfaces were contoured by using geographic information system software. These contours were imprecise in some areas because the software could not fully evaluate the hydrology given available information; therefore, contours were manually modified where necessary. The ability to evaluate differences in water levels between 1990-1999 and 2000-2009 is limited in some areas because most of the monitoring sites did not have 80 percent complete records for one or both of these periods. The quality of the analyses was limited by (1) deficiencies in spatial coverage; (2) the combination of pre- and post-construction water levels in areas where canals, levees, retention basins, detention basins, or water-control structures were installed or removed; (3) an inability to address the potential effects of the vertical hydraulic head gradient on water levels in wells of different depths; and (4) an inability to correct for the differences between daily water-level statistics. Contours are dashed in areas where the locations of contours have been approximated because of the uncertainty caused by these limitations. Although the ability of the maps to depict differences in water levels between 1990-1999 and 2000-2009 was limited by missing data, results indicate that near the coast water levels were generally higher in May during 2000-2009 than during 1990-1999; and that inland water levels were generally lower during 2000-2009 than during 1990-1999. Generally, the 25th, 50th, and 75th percentiles of water levels from all months were also higher near the coast and lower inland during 2000–2009 than during 1990-1999. Mean October water levels during 2000-2009 were generally higher than during 1990-1999 in much of western Miami-Dade County, but were lower in a large part of eastern Miami-Dade County.

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    Metadata Date August 12, 2020
    Metadata Created Date March 22, 2021
    Metadata Updated Date March 22, 2021
    Reference Date(s) January 1, 2016 (publication)
    Frequency Of Update unknown

    Metadata Source

    Harvested from USGS-Harvest

    Additional Metadata

    Resource Type Dataset
    Metadata Date August 12, 2020
    Metadata Created Date March 22, 2021
    Metadata Updated Date March 22, 2021
    Reference Date(s) January 1, 2016 (publication)
    Responsible Party U.S. Geological Survey (Point of Contact)
    Contact Email
    Access Constraints Use Constraints: none, Access Constraints: none
    Bbox East Long -80.146031
    Bbox North Lat 26.119128
    Bbox South Lat 25.074456
    Bbox West Long -80.964855
    Coupled Resource
    Frequency Of Update unknown
    Harvest Object Id 63996336-f82c-4c8f-b118-a6d650cd9425
    Harvest Source Id 5f135382-acf8-4ee0-8a68-2db6433e8a82
    Harvest Source Title USGS-Harvest
    Licence See access and use constraints information.
    Metadata Language eng; USA
    Metadata Type geospatial
    Progress completed
    Spatial Data Service Type
    Spatial Reference System
    Spatial Harvester True
    Temporal Extent Begin 1989-10-01T010000
    Temporal Extent End 2009-09-30T010000

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