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The Ogallala Aquifer of the central United States is one of the world's great aquifers, but in places it is being rapidly depleted by growing municipal use, and continuing agricultural use. This huge aquifer, which underlies portions of eight states, contains primarily fossil water from the time of the last glaciation .
Energy savings that can be achieved with ATES depend strongly on site geology. ATES requires the presence of a suitable aquifer that is able to accept and yield water. For example solid rock limits access to the aquifer. Thick (>10 m) sandy aquifers are optimal. Sufficient hydraulic conductivity is required, enough that water flows easily.
This shallow recharged water is then recovered as potable water and injected into the deep basalt aquifer. [citation needed] During the injection process, electrical energy can be generated by the head pressure of the water flowing back into the aquifer. This stored water is recovered during late summer and early autumn for irrigation needs.
Transmissivity is the product of hydraulic conductivity and the aquifer thickness (typically used as an indication of the ability of an aquifer to deliver water to a well). Intrinsic permeability ( κ ) is a property of the porous medium alone, and does not change with different fulids (e.g. different density or viscosity; it is used more in ...
Hence the actual amount of water that can be extracted from the unit volume of aquifer by pumping or under the action of gravity is called as specific yield. The fraction of water held back in the aquifer is known as specific retention. Thus it can be said that porosity is the sum of specific yield and specific retention.
The change in the chemical composition of groundwater is an indicator of seawater intrusion. It prevents the multi-sources of chloride , leading to a change in salinity of groundwater. Chemical concentration ratios including Na/Cl, Ca/Cl, Mg/Ca, Cl/Br, Ca/Mg and Cl/HCO3 can be used to distinguish the seawater intrusion.
Use of groundwater, especially for irrigation, may also lower the water tables. 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.
The energy balance of groundwater flow can be applied to flow of groundwater to subsurface drains. [2] The computer program EnDrain [3] compares the outcome of the traditional drain spacing equation, based on Darcy's law together with the continuity equation (i.e. conservation of mass), with the solution obtained by the energy balance and it can be seen that drain spacings are wider in the ...