Seep (hydrology) in the context of "Ground-water"

Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available fresh water 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 Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells.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.

Typically, groundwater is thought of as water flowing through shallow aquifers, but, in the technical sense, it can also contain soil moisture, permafrost (frozen soil), immobile water in very low permeability bedrock, and deep geothermal or oil formation water. Groundwater is hypothesized to provide lubrication that can possibly influence the movement of faults. It is likely that much of Earth's subsurface contains some water, which may be mixed with other fluids in some instances.

In ecology, a mesic habitat is a type of habitat with a well-balanced or moderate supply of moisture throughout the growing season (e.g., a mesic forest, temperate hardwood forest, or dry-mesic prairie). The term derives from the Greek mesos, meaning middle, indicating its relative moisture content between hydric (moist) and xeric (dry) habitats. The word "mesic" can apply to the plants or soils within the mesic habitat (i.e. mesic plants, mesic soils).

Mesic habitats provide a moderate moisture content that remains relatively constant during crucial growing periods. A variety of outside factors contribute to the presence of water in the system, including streams and their offshoots, wet meadows, springs, seeps, irrigated fields, and high-elevation habitats. These factors effectively provide drought insurance during the growing season against climatic factors such as increasing temperatures, lack of rain, and the effects of urbanization.

In hydrogeology, groundwater flow is defined as the "part of streamflow that has infiltrated the ground, entered the phreatic zone, and has been (or is at a particular time) discharged into a stream channel or springs; and seepage water." It is governed by the groundwater flow equation.Groundwater is water that is found underground in cracks and spaces in the soil, sand and rocks. Where water has filled these spaces is the phreatic (also called) saturated zone. Groundwater is stored in and moves slowly (compared to surface runoff in temperate conditions and watercourses) through layers or zones of soil, sand and rocks: aquifers. The rate of groundwater flow depends on the permeability (the size of the spaces in the soil or rocks and how well the spaces are connected) and the hydraulic head (water pressure).

In polar regions groundwater flow may be obstructed by permafrost.