BrandTech Vacuum Conversion Unit Calculator (Pressure) Vacuum Depth Calculator. **Vacuum measurements in the USA are often made in inches of mercury below atmospheric pressure. The values calculated here assume standard atmospheric pressure of 29.92 inches of mercury.
Perched aquifer: Localized zone of saturation above the main water table created by a laterally limited layer of underlying impermeable material. Permeable/Permeability: Capable of transmitting water (porous rock, sediment, or soil); the rate at which water moves through rocks or soil.Permeable layer: A layer of porous material (rock or unconsolidated sediment); in an aquifer, the layer through which water freely passes as it moves through the subsurface.Pore space: Openings between geologic material found underground.Also referred to as void space or interstices.erched aquifer: Localized zone of saturation above the main water table created by a laterally limited layer of underlying impermeable material. Permeable/Permeability: Capable of transmitting water (porous rock, sediment, or soil); the rate at which water moves through rocks or soil.
In the saturated zone (below the water table) water percolates through the interconnected pore spaces, moving downward by the force of gravity, and upward toward zones of lower pressure. Where the water table intersects the surface, such as at a surface stream, lake, or swamp, the groundwater returns to the surface.he rate at which groundwater moves through the saturated zone depends on the permeability of the rock and the hydraulic gradient. The hydraulic gradient is defined as the difference in elevation divided by the distance between two points on the water table.