| A | B |
|---|
| aeration zone | zone immediately below the land surface where the pores contain both water and air, but are not totally saturated with water. Also known as the unsaturated zone. |
| aquifer | underground geological formation able to store and yield water |
| cone of depression | zone around a well in an unconfined aquifer that is normally saturated, but becomes unsaturated as a well is pumped, leaving an area where the water table dips down to form a cone shape |
| confining layer | material with little or no permeability or hydraulic conductivity. Water does not pass through this layer or the rate of movement is extremely slow |
| depletion | loss of water from surface water reservoirs or groundwater aquifers at a rate greater than that of recharge |
| discharge | outflow of water from a stream, pipe, groundwater aquifer or watershed (opposite of recharge) |
| drawdown | lowering of the groundwater level caused by pumping |
| flow rate | time required for a volume of groundwater to move between points (usually only inches ay year) |
| groundwater | water found in the spaces between soil particles and cracks in rocks underwater (located in the saturation zone) |
| hyrdologic cycle (water cycle) | path water takes through its various states of matter as is moves throughout ocean, atmosphere, groundwater, streams, etc. |
| impermeable layer | layer of material (such as clay) in a aquifer through which water does not pass |
| infiltration | flow of water from the land surface into the subsurface |
| infiltration rate | quantity of water that enters the soil surface in a specified time interval (volume of water per unit of soil surface area per unit of time) |
| monitoring well | non-pumping well, usually smaller in diameter, that is used to measure the elevation of a water table or water quality |
| overwithdrawal | withdrawal of groundwater over a period of time that exceeds the recharge rate of the supply aquifer (overdraft or mining the aquifer) |
| permeable | capable of transmitting water (porous soil or rock) |
| permeability | rate at which water moves through rocks or soil |
| permeable layer | layer of porous material (rock, soil, unconsolidated sediment) in an aquifer, the layer through which water freely passes as it moves through the ground |
| plume | underground pattern of contaminant concentrations created by movement of groundwater beneath a contaminant source (concentration decreases as the water moves away from the source site) |
| pore space | also called void spaces; openings between geologic material found underground |
| porosity | ratio of the volume of void or air spaces in a rock or sediment to the total volume of the rock or sediment (saturated sand-20% water, 25% gravel and 48% clay) |
| recharge | water added to an aquifer (rain, adding water to a well (injection wells) |
| recharge rate | rate at which a quantity of water per unit of time that replenishs or refills an aquifer |
| recharge zone or area | area where permeable soil or rock allows water to seep into the ground to replenish an aquifer |
| remediation | containment, treatment or removal of contaminated groundwater (may include the removal of contaminated soil about the groundwater) |
| residence time | period of time that groundwater |
| safe yield (sustainable yield) | annual amount of water that can be taken from a source of supply over a period of years without depleting that source beyond its ability to naturally recharge |
| salt water intrusion | process by which an aquifer is overdrafted creating a flow imbalance within an area taht results in salt water encroaching into a fresh water supply |
| saturation zone | portion below the earth's surface that is saturated with water (upper surface of this zone which is open to atmospheric pressure is known as the water table) |
| subsidence | depression of the land surface as a result of groundwater being pumped (cracks/fissures appear in the land and are virtually irreversible) |
| surface water | water above the surface of the land (lakes, rivers, streams, ponds, floodwater or runoff) |
| water table | top of an unconfined aquifer (level below which soil and rock are saturated with water) |
| well | bored, drilled or driven shaft or dug whole, whose depth is greater than the largest surface dimension and whose purpose is to reach underground water supplies to inject, extract or monitor water |
| well closure | sealing a well that is no longer being used to prevent groundwater contamination and harm to people and animals |
| well sitting | location of a well placed to best protect water quality, access adequate water quantity, and allow for inspection or maintenance of the well |
| wellhead protection area | protected surface and subsurface zone surrounding a well or well field supplying a public water system to keep contaminants from reaching the well water |
| withdrawal | water removed from a surface or groundwater for use |
