"Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations."
The water that is present below the ground surface in soil pore spaces and in the fractures of rock formations.
Aquifers: Underground layers of permeable rock or sediment that contain and transmit groundwater.
Vadose zone: The unsaturated zone above the water table, where water is present but not fully saturated.
Saturated zone: The area below the water table where all the pores are filled with water.
Permeability: The measure of a material's ability to allow fluids to pass through it.
Porosity: The measure of a material's ability to hold water.
Groundwater flow: The movement of water through an aquifer due to gravity and pressure gradients.
Recharge: The process by which water enters the aquifer from the surface.
Discharge: The process by which water leaves the aquifer, often through springs or wells.
Water table: The level at which the pore spaces in the ground are filled with water, separating the saturated and unsaturated zones.
Hydrogeology: The study of the distribution and movement of groundwater in the earth's crust.
Groundwater contamination: The introduction of pollutants into the groundwater system.
Groundwater management: The processes and strategies used to manage and protect groundwater resources.
Groundwater modeling: The use of mathematical models to predict and analyze groundwater flow and transport.
Groundwater monitoring: The ongoing measurement and analysis of groundwater levels and quality.
Groundwater recharge zones: Areas where water infiltrates into the aquifer, such as wetlands or recharge basins.
Groundwater depletion: The reduction of groundwater levels due to overuse or drought.
Groundwater sustainability: The ability to maintain the long-term availability and quality of groundwater resources.
Karst hydrology: The study of the unique hydrology of karst terrain, which features limestone formations and underground caverns.
Groundwater and climate change: The impact of climate change on groundwater resources and management strategies.
Groundwater laws and regulations: The legal framework that governs the use and management of groundwater resources.
Shallow groundwater: Shallow groundwater is found relatively close to the surface, usually in the first few meters. It is often found in soil and is influenced by surface water.
Confined groundwater: Confined groundwater is located in an area between two layers of impermeable rock or sediment, which does not allow water to flow through it easily. It is often under high pressure and can be used as a source of artesian wells.
Fractured rock groundwater: Fractured rock groundwater is found in areas with fractured bedrock, which allows water to move more easily through it. This type of groundwater is common in mountainous regions.
Karst groundwater: Karst groundwater is found in areas with soluble rocks, such as limestone or dolomite. The water can form underground caves and rivers due to the dissolving of the rock by water.
Glacial groundwater: Glacial groundwater is located in areas where glaciers have receded, leaving behind permeable deposits of sand and gravel that can hold water. These deposits are often called moraines, and they are a common source of groundwater.
Volcanic groundwater: Volcanic groundwater is found in areas with volcanic rocks, such as basalt or andesite. This type of groundwater is often heated and can contain minerals and gases, making it valuable for geothermal energy.
Saltwater intrusion: Saltwater intrusion occurs when saltwater infiltrates freshwater aquifers, often due to over-pumping of groundwater or sea-level rise. It can render groundwater unusable for drinking or irrigation purposes.
Fossil groundwater: Fossil groundwater is located in deep underground aquifers that were filled long ago, often during times when the climate was wetter. It can be difficult to access and may be of low quality due to its long residence time in the ground.
"About 30 percent of all readily available freshwater in the world is groundwater."
"A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water."
"The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table."
"Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands."
"Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells."
"The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology."
"It is likely that much of Earth's subsurface contains some water, which may be mixed with other fluids in some instances."
"Groundwater is often cheaper, more convenient, and less vulnerable to pollution than surface water."
"Groundwater provides the largest source of usable water storage in the United States."
"California annually withdraws the largest amount of groundwater of all the states."
"Over 2 billion people rely on it as their primary water source worldwide."
"Major sources include industrial and household chemicals and garbage landfills, excessive fertilizers and pesticides used in agriculture, industrial waste lagoons, tailings and process wastewater from mines, industrial fracking, oil field brine pits, leaking underground oil storage tanks and pipelines, sewage sludge and septic systems."
"Groundwater is susceptible to saltwater intrusion in coastal areas."
"Land subsidence when extracted unsustainably, leading to sinking cities (like Bangkok) and loss in elevation (such as the multiple meters lost in the Central Valley of California)."
"Polluted groundwater is less visible and more difficult to clean up than pollution in rivers and lakes."
"These issues are made more complicated by sea level rise and other changes caused by climate changes which will affect the water cycle."
"Earth's axial tilt has shifted 31 inches because of human ground water pumping."