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36 terms
Terms | Definitions |
|---|---|
 aeration zone | the zone immediately below the lands surface where the pores contain both water and air but are not totally saturated with water. plant roots can capture the moisture passing through this zone, but it cannot provide water for wells. Also known as the unsaturated zone. |
| aquifer | underground bed or layer yielding ground water for wells and springs etc |
| cone of depression | The 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. The shape of the cone is influenced by porosity and the water yield or pumping rate of the well. |
| confining layer | Geologic 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 | The loss of water from surface water reservoirs or groundwater aquifers at a rate greater than that of recharge. |
| discharge | An outflow of water from a stream, pipe, groundwater aquifer, or watershed; the opposite of recharge. |
| drawdown | A lowering of the groundwater level caused by pumping. |
| flow rate | The time required for a volume of groundwater to move between points. Typically groundwater moves very slowly—sometimes only inches per year. |
| groundwater | water that fills tiny cracks and holes in the rock layers below the earth's surface |
| hydrologic cycle | (also known as the water cycle) The paths water takes through its various states--vapor, liquid, solid--as it moves throughout the oceans, atmosphere, groundwater, streams, etc. |
| impermeable layer | A layer of material (such as clay) in an aquifer through which water does not pass. |
| infiltration | Flow of water from the land surface into the subsurface. |
| infiltration rate | The quantity of water that enters the soil surface in a specified time interval. Often expressed in volume of water per unit of soil surface area per unit of time. |
| monitoring well | A non-pumping well, generally of small 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. Also referred to as overdraft or mining the aquifer. |
| permeable | capable of transmitting water the rate at which water moves through rocks or soil |
| permeable layer | A layer of porous material (rock, soil, unconsolidated sediment); in an aquifer, the layer through which water freely passes as it moves through the ground. |
| pore space | Openings between geologic material found underground. Also referred to as void space or interstices. |
| porosity | The ratio of the volume of void or air spaces in a rock or sediment to the total volume of the rock or sediment. The capacity of rock or soil to hold water varies with the material. For example, saturated sand contains about 20% water; gravel, 25%; and clay, 48%. |
| recharge | new water that enters the aquifer from the surface |
| recharge rate | The quantity of water per unit of time that replenishes or refills an aquifer. Recharge zone or area: An area where permeable soil or rock allows water to seep into the |
| recharge zone or area | An area where permeable soil or rock allows water to deep into the ground to replenish an aquifer. |
| remediation | Containment, treatment or removal of contaminated groundwater. May also include containment, treatment or removal of contaminated soil above the water table. |
| residence time | the average amount of time that a nutrient spends in a given source or pool. |
| safe yield | The 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 be replenished naturally in "wet years." Also called sustainable yield. |
| salt water intrusion | Process by which an aquifer is overdrafted creating a flow imbalance within an area that results in salt water encroaching into fresh water supply. |
| saturation zone | The portion below the earth's surface that is saturated with water is called the zone of saturation. The upper surface of this zone, open to atmospheric pressure, is known as the water table. |
| subsidence | a depression of the land surface as a result of groundwater being pumped |
| surface water | water above the surface of the land, including lakes, rivers,etc. |
| water table | the top of an aquifer |
| well | a bored,drilled or driven shaft or a dug hole 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 | The process of sealing a well that is no longer being used to prevent groundwater contamination and harm to people and animals. |
| well siting | Location of a well placed to best protect water quality, access adequate water quantity, and allow for inspection and maintenance of the well. |
| wellhead protection area | A 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 source for use |
| plume | in groundwater a plume is an underground pattern of contaminant concentrations created by the movement of groundwater beneath a contaminant source. Contaminants spread mostly laterally in the direction of groundwater movement. The source site has the highest concentration, and the concentration decreases away from the source. |
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