The use of a GIS to compare the land areas captured by very basic and complex wellhead protection area models.* It is estimated that over 65 percent of Washington State citizens rely on groundwater as a source of drinking water drinking water supply of water available to animals for drinking supplied via nipples, in troughs, dams, ponds and larger natural water sources; an insufficient supply leads to dehydration; it can be the source of infection, e.g. leptospirosis, salmonellosis, or of poisoning, e.g. . * In some counties, the numbers approach 100 percent. * The delineation of wellhead well·head n. 1. The source of a well or stream. 2. A principal source; a fountainhead. 3. The structure built over a well. wellhead Noun 1. protection areas (WHPAs) is a proactive method of protecting the land areas around public water supply wells. * A wellhead protection area is commonly defined as the surface and subsurface area that surrounds a well field, well, or spring that supplies a public drinking-water system. * The Washington State Department of Health (WSDOH WSDOH Washington State Department of Health ) accepts four methods for the delineation of these areas: 1. the calculated-fixed-radius (CFR CFR See: Cost and Freight ) method, 2. the analytical method, 3. hydrogeologic mapping, and 4. the numerical flow/transport model. * The analytical, hydrogeologic, and numerical models are generally considered to be superior to the CFR model. * The hydrogeologic and numerical models are considered to be more sophisticated than the analytical model. * The study reported here utilized a geographic information system geographic information system (GIS) Computerized system that relates and displays data collected from a geographic entity in the form of a map. The ability of GIS to overlay existing data with new information and display it in colour on a computer screen is used primarily to (GIS) to compare the very basic CFR method with other methods for water systems in Whatcom County, Washington Whatcom County (IPA: [ʍɑt kəm]) is a county located in the U.S. state of Washington. Its name ultimately derives from a Nooksack word meaning "noisy water."[1] As of 2000, the population was 166,814. . * The 1-, 5-, and 10-year overall comparison averages show that the CFR and hydrogeologic GIS overlays were the most similar for each of the three study comparison areas. * The CFR and the analytical methods produced the least similar overlays. * These results allow for more confidence in the CFR method, especially for areas closer to a well. * Local health and planning departments can provide public wells with a level of protection by simply using the CFR method, either as an interim measure or as a final model. * A local health department working toward permanent or interim protection for public drinking-water-system wellheads might adopt the following procedure: 1. establish a GIS with standard base maps, 2. map the location of any public supply wells with a global positioning system Global Positioning System: see navigation satellite. Global Positioning System (GPS) Precise satellite-based navigation and location system originally developed for U.S. military use. , 3. buffer these wells according to the volumetric volumetric /vol·u·met·ric/ (vol?u-met´rik) pertaining to or accompanied by measurement in volumes. vol·u·met·ric adj. Of or relating to measurement by volume. CFR method in GIS, 4. add any noncircular (more-advanced-model) wellhead protection areas to the GIS, and 5. work with the local water systems and any local or state agencies to recognize the wellhead protection areas in land use decisions. |
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