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Groundwater
| Term | Definition |
|---|---|
| Groundwater | All the subsurface water trapped in the pores and other open spaces in rocks, sediments and soils; .75% of total water available for use and 30.1% of fresh water resources; movement averages a few meters per day, slower than streams; used for irrigation |
| Pores | Groundwater is stored in open spaces in rocks |
| Porosity | The percentage of a material's total volume that is open space (%) |
| Permeability | The capacity to transmit fluids; open spaces must be connected for fluid to move. This is necessary if we are to produce water from rocks; Dependent on porosity, but also on the size of the pores and their interconnections |
| High Permeability | Higher flow rates; small grains usually produce low permeability; Conduits produce high permeability; Large grains without clay and silt matrix tend to have excellent permeability |
| Aquifer | A permeable underground rock layer saturated with slowly moving groundwater. |
| Sandstones | The best aquifers are well-sorted, loosely & cemented, capillary pressure helps to hold the water |
| Aquiclude | A non-permeable layer that prevents the flow of water. Ex: clay or shale layers |
| Confined aquifer | An aquifer with an aquiclude above and below |
| Phreatice Zone (Zone of Saturation) | The region of groundwater where all pore spaces are filled with fluids |
| Vadose Zone (Zone or Aeration) | The region of groundwater where most pore spaces are filled with vapor (unsaturated zone) |
| Suspended Water | Water that is in the vadose zone as a result of adhesion to grain boundaries and capillary pressure |
| Water Table | A planar surface which occurs at the top of the phreatic zone, level fluctuates with precipitation, infiltration, etc. |
| Water Table Dynamics | In areas with adequate precipitation, the water table surface will mimic land surface, rising under hills, and flowing down to streams or areas of lower pressure |
| Gaining Streams | Have water flowing to the stream from the ground; these stay around despite recent precipitation |
| Losing Streams | Have water leaving the channel and infiltrating the ground; these only run for a few hours after precipitation event |
| Natural Springs | Where flowing water exits the ground; occurring at locations where the landscape intersects the water table; water can be flowing along beds of rock or through faults and fractures in the rock |
| Artesian Aquifers | Confined aquifers that have constant pressure and recharge; only need a well to get water |
| Elevation of the Water Table | In the recharge area and the distance from this area will determine the pressure = how high the water will rise |
| Water Wells | Wells that penetrate into the water table in an aquifer and either flow naturally or/and pumped to bring water to the surface |
| Cone of Depression | When pumping water from an aquifer at a rate higher than the groundwater is flowing back into the aquifer; then the water will flow towards the well forming this |
| Recharge Zone | Where surface water infiltrates the ground and replenishes the aquifer; surface water recharge is from rainfall, melting snow & losing streams; can take 1000's of years to replenish some aquifers |
| Karst Topography | Denotes a landscape that is dominated by soluble rock (limestones, dolomites, gypsum) and dissolution features in humid environments |
| Sinkholes | Either dissolution or collapse |
| Solution Valleys | Coalescing sinkholes |
| Natural Bridges | Remaining land between sinkholes |
| Disappearing Streams | Underground conduits for water |
| Tower Karst | Extensive dissolution |
| Caves and Caverns | Underground features associated with groundwater; these form when acid water dissolves limestone below the surface slowly creating voids in the rock; gradually grow larger and larger forming themselves |
| Speleothems | These are features in caves; such as stalactites, stalagmites, columns and drapery formations |
| Cave | Any natural opening in the subsurface that forms a cavity large enough for human entry; Texas definition: void must at least be 5 meters in traverse length & have no dimension of entrance that exceeds length or depth |
| Cavern | Very large cave or system of interconnected caves passages |
| Grotto | Small cave or an individual room within a cavern |
| Krubera Cavern | Deepest cave in the world; water percolates through deep faults and fractures formed by orgenic stresses, these are accentuated through dissolution of limestone |
| Cave of Crystals | Cavern found in a lead, zinc, & silver mine; Giant gypsum crystals that are growing in a fluid filled cavity; a giant geode |
| Caves in Quartzite | Caves formed over millions of years form by fracturing & dissolution of quartz; Ridges rise up from the valley floors, covered in vegetation; requires help of organic acids; speleothems formed from opal |
| Quicksand | Sand or other unconsolidated sediment that is super saturdated with water, such that grains are buoyantly held away from one another; |
| Quicksand Occurs at: | Groundwater discharge zones Upward flow of groundwater Springs, streamboats, coasts **High density but highly visocous |
| Tufa | Surface carbonate speleothem formed by the precipitation of mineral entering atmospheric conditions, result of: Degassing, Change in temp, Interaction w/ biota; Similar to: Silica Dioxide & Calcium sulfate |
| Hydrothermal fluids | Groundwater that is heated above the average annual mean temperature, as a result of: Volcanism, radioactive decay, Deep-circulation (geothermal gradient) |
| Hot Springs | AKA Thermal & warm springs; Thermal waters are brought to the surface and discharged, usually as artesian waters; mudpots can form when thermal water alters bedrock to produce hydrated clays that "bubble" |
| Geysers | Hot springs that eject water & steam; constricted permeability (conduits) enable pressure to build up within system; as pressure increases, gases spontaneously expand to forcefully eject water and steam |
| Water Quality | Extraction can result in a decrease in water quality as a result of increased leakage from surrounding area |
| Subsidence | Lowering of the regional land surface due to grain compaction as a result of the loss of buoyant support as a result groundwater extraction |
| Collapse | Local lowering of the land surface, often catastrophically, as a result of the loss of buoyant support as a result of groundwater extraction |
| Groundwater Contamination | Sources of potential anthropogenic groundwater contamination abound; Ex: Septic tanks, landfills, waste injection wells, Toxic chemical disposal, cemetaries, etc. |
| Groundwater Quality | General related to 4 things: Composition of aquifer rock Solubility of aquifer rock Residence time of aquifer fluid External contaminents |
| Hard water | Water that has a high dissolved solute load, which is often associated with scale deposition |
| Severe health problems | Can develop from high levels of natural minerals such as arsenic (slow poison that can cause cancer) |
Created by:
FaithRaquel2015
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