An underground layer of water-bearing permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well.
The area of land where precipitation collects and drains off into a common outlet, such as a river, bay, or other body of water.
The volume rate of water flow that is transported through a given cross-sectional area, including any suspended solids (e.g. sediment), dissolved chemicals, or biologic material (e.g. diatoms) that is mixed with the water molecules.
The process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants.
Water located beneath the ground surface in soil pore spaces and in the fractures of rock formations.
Levels of water in a hydrographic basin, which is an area of land that drains rain water or snow into one location such as a stream, lake, wetland, or groundwater.
The average amount of precipitation that flows over the land as surface water within a month rather than infiltrating the surface or evaporating.
Water on the earth's surface exposed to the atmosphere such as rivers, lakes, and creeks.
The sum of all water stored on the surface or underground within a basin, including snow, surface water, soil moisture, and groundwater.
An accounting of all water inflows, outflows, and changes in storage within a hydrologic system.
