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Lightweight expanded clay aggregate (LECA) or expanded clay (exclay) is a lightweight aggregate made by heating clay to around 1,200 °C (2,190 °F) in a rotary kiln. The heating process causes gases trapped in the clay to expand, forming thousands of small bubbles and giving the material a porous structure.
Aquifers of the United States Withdrawal rates from the Ogallala Aquifer.. This is a list of some aquifers in the United States.. Map of major US aquifers by rock type. An aquifer is a geologic formation, a group of formations, or a part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to groundwater wells and springs.
The Groundwater Ambient Monitoring and Assessment Program (GAMA) is an all-inclusive monitoring program for groundwater that was implemented in 2000 in California, United States. It was created by the California State Water Resources Control Board as an improvement from groundwater programs that were already in place.
The National Ground Water Association (NGWA), headquartered in Westerville, Ohio, is a membership-based nonprofit organization. Founded in 1948, the organization is composed of United States and international groundwater professionals in four membership divisions: water well contractors, scientists and engineers, manufacturers, and suppliers.
Groundwater recharge is an important process for sustainable groundwater management, since the volume-rate abstracted from an aquifer in the long term should be less than or equal to the volume-rate that is recharged. Recharge can help move excess salts that accumulate in the root zone to deeper soil layers, or into the groundwater system.
Explore current groundwater conditions in this interactive map: Patterns emerged. Many of the communities most exposed to flooding were built along historical creeks or on top of filled-in wetlands.
Drawdown is often represented in cross-sectional diagrams of aquifers. A record of hydraulic head, or rate of flow , versus time is more generally called a hydrograph (in both groundwater and surface water). The main contributor to groundwater drawdown since the 1960s is over-exploitation of groundwater resources. [2]
The transient flow of groundwater is described by a form of the diffusion equation, similar to that used in heat transfer to describe the flow of heat in a solid (heat conduction). The steady-state flow of groundwater is described by a form of the Laplace equation, which is a form of potential flow and has analogs in numerous fields.