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Definition
| A subsurface rock or sediment unit that is porous and permeable. To be an aquifer it must have these traits to a high enough degree that it stores and transmits useful quantities of water. |
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artesian formation [image] |
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Definition
| The arrangment of permeable layer sanwhiched between two layers of impermeable rock. |
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evapotranspiration [image] |
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Definition
| Loss of moisture of water vapor from the ground or from plant leaves. |
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Definition
| A hot spring that intermittently erupts a spray of steam and hot water. Caused by the heating of ground water within a confined opening in hot rock. |
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| Water of Earth including surface and sub-surface water. |
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| A layer of rock, sediment or soil that does not allow water to pass through. This could be caused by a lack of pore space or pore spaces that are so small that water molecules have difficulty passing through. |
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Definition
| A measure of how well a material can transmit water. Materials such as gravel, that transmit water quickly, have high values of permeability. Materials such as shale, that transmit water poorly, have low values. Permeability is primarily determined by the size of the pore spaces and their degree of interconnection. Permeability measures are expressed in units of velocity, such as centimeters per second, and assume a gradient of one vertical foot of drop per linear foot. |
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Definition
| The volume of pore space in a rock, sediment or soil. Usually expressed as a percentage. This pore space can include openings between grains, fracture openings and caverns. |
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Definition
| Water added to an aquifer or other water body. An aquifer is recharged by precipitation in an area where the aquifer has a porous connection to the surface. |
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Definition
| Condition of having rainfall greater than the need for moisture when the soil is alredy saturated. |
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Definition
| The condition where plants draw water from the soil at times when the need for moisture is greater than the rainfall. |
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Definition
| Describes the inincome and the spending of water in a region. |
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Definition
| The movement of water between the atmosphere, ground and surface water bodies through the processes of evaporation, precipitation, infiltration, percolation, transpiration and runoff. Also known as the "hydrologic cycle". |
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Definition
| A level beneath the Earth's surface, below which all pore spaces are filled with water and above which the pore spaces are filled with air. The top of the zone of saturation in a subsurface rock, soil or sediment unit. |
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