CHAPTER 17: GROUNDWATER Aquifer : Rock or sediment through which groundwater moves easily. Aquitard : An impermeable bed that hinders or prevents groundwater movement. Artesian well : A well in which the water rises above the level where it was initially encountered. Cavern : A naturally formed underground chamber or series of chambers most commonly produced by solution activity in limestone. Cone of depression : A cone-shaped depression in the water table immediately surrounding a well. Darcy's law : An equation stating that groundwater discharge depends on the hydraulic gradient, hydraulic conductivity, and cross-sectional area of an aquifer. Flowing artesian well : An artesian well in which water flows freely at Earth's surface because the pressure surface is above ground level. Gaining ( effluent ) stream : Streams that gain water from the inflow of groundwater through the streambed. Geyser : A fountain of hot water ejected periodically from the ground. Groundwater : Water in the zone of saturation. Hot spring : A spring in which the water is 6-9 C (10-15F) warmer than the mean annual air temperature of its locality. Hydraulic gradient : The slope of the water table. It is determined by finding the height difference between two points on the water table and dividing by the horizontal distance between the two points. Karst topography : A type of topography formed on soluble rock (especially limestone) primarily by dissolution. It is characterized by sinkholes, caves, and underground drainage. Porosity : The volume of open spaces in rock or soil. Nonflowing artesian well : An artesian well in which water does not rise to the surface because the pressure surface is below ground level. Losing ( influent ) stream : Stream that loses water to the groundwater system by outflow through the streambed. Permeability : A measure of a material's ability to transmit water. Sinkhole : A depression produced in a region where soluble rock has been removed by groundwater. Perched water table : A localized zone of saturation above the main water table, created by an impermeable layer (aquiclude) Speleothem : A collective term for the dripstone features found in caverns. Spring : A flow of groundwater that emerges naturally at the ground surface.
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- Spring '09
- Geology, water table, aquitards