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The water cycle (or hydrologic cycle or hydrological cycle ), is a biogeochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time. However, the partitioning of the water into the major reservoirs of ice, fresh water, salt water and ...
The total volume of water on Earth is estimated at 1.386 billion km 3 (333 million cubic miles), with 97.5% being salt water and 2.5% being freshwater. Of the freshwater, only 0.3% is in liquid form on the surface. [ 2][ 3][ 4] Because the oceans that cover roughly 70.8% of the area of Earth reflect blue light, Earth appears blue from space ...
A geographic information system ( GIS) consists of integrated computer hardware and software that store, manage, analyze, edit, output, and visualize geographic data. [ 1][ 2] Much of this often happens within a spatial database; however, this is not essential to meet the definition of a GIS. [ 1] In a broader sense, one may consider such a ...
Hydrology (from Ancient Greek ὕδωρ (húdōr) 'water' and -λογία ( -logía) 'study of') is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydrologist.
Water table. Cross-section of a hillslope depicting the vadose zone, capillary fringe, water table, and the phreatic or saturated zone. (Source: United States Geological Survey .) The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater ...
Water balance in a basin. A general water balance equation is: [ 5] P = Q + ET + ΔS. where. P is precipitation. Q is streamflow. ET is evapotranspiration. ΔS is the change in storage (in soil or the bedrock / groundwater) This equation uses the principles of conservation of mass in a closed system, whereby any water entering a system (via ...
An aquifer is an underground layer of water -bearing material, consisting of permeable or fractured rock, or of unconsolidated materials ( gravel, sand, or silt ). Aquifers vary greatly in their characteristics. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which ...
A shaded-relief topo map of the Taum Sauk pumped storage plant in Missouri, United States. The lake on the mountain is built upon a flat surface, requiring a dam around the entire perimeter. In 2010, the United States had 21.5 GW of pumped storage generating capacity (20.6% of world capacity). [69]