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The specific storage is the amount of water that a portion of an aquifer releases from storage, per unit mass or volume of the aquifer, per unit change in hydraulic head, while remaining fully saturated. Mass specific storage is the mass of water that an aquifer releases from storage, per mass of aquifer, per unit decline in hydraulic head:
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. Specific yield of soils differ from each other in the sense that some soil types have strong molecular attraction with the water held in their pores while others have less.
Typically this equation is used to find the average T and S values near a pumping well, from drawdown data collected during an aquifer test. This is a simple form of inverse modeling, since the result ( s ) is measured in the well, r , t , and Q are observed, and values of T and S which best reproduce the measured data are put into the equation ...
The above groundwater flow equations are valid for three dimensional flow. In unconfined aquifers, the solution to the 3D form of the equation is complicated by the presence of a free surface water table boundary condition: in addition to solving for the spatial distribution of heads, the location of this surface is also an unknown. This is a ...
Specific yield (S y) is also a ratio between 0 and 1 (S y ≤ porosity) and indicates the amount of water released due to drainage from lowering the water table in an unconfined aquifer. The value for specific yield is less than the value for porosity because some water will remain in the medium even after drainage due to intermolecular forces.
Cloud storage offers a convenient way to back up important files and photos, and even to maximize your hard drive space to store files you really need, rather than those you only access once in a...
In 1907, Edgar Buckingham created the first water retention curve. [2] It was measured and made for six soils varying in texture from sand to clay. The data came from experiments made on soil columns 48 inch tall, where a constant water level maintained about 2 inches above the bottom through periodic addition of water from a side tube.
Public Storage currently pays a quarterly dividend of $3.00 per share, equating to an annualized dividend of $12.00 per share, which gives its stock a yield of about 4.4% at the time of this writing.