An aquifer is an underground layer of water-bearing material, consisting of permeable or fractured rock, or of unconsolidated materials. 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 is a bed of low permeability along an aquifer, and aquiclude, which is a solid, impermeable area underlying or overlying an aquifer, the pressure of which could lead to the formation of a confined aquifer. The classification of aquifers is as follows: Saturated versus unsaturated; aquifers versus aquitards; confined versus unconfined; isotropic versus anisotropic; porous, karst, or fractured; transboundary aquifer.
The Ogallala Aquifer is a shallow water table aquifer surrounded by sand, silt, clay, and gravel located beneath the Great Plains in the United States. As one of the world's largest aquifers, it underlies an area of approximately 174,000 sq mi (450,000 km2) in portions of eight states. It was named in 1898 by geologist N. H. Darton from its type locality near the town of Ogallala, Nebraska. The aquifer is part of the High Plains Aquifer System, and resides in the Ogallala Formation, which is the principal geologic unit underlying 80% of the High Plains.
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 freshwater 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 Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells.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.
Lake Nasser is a vast reservoir in southern Egypt and northern Sudan. It is one of the largest man-made lakes in the world. Before construction, Sudan was against the building of Lake Nasser, because it would encroach on land in the northern part of the country, where many Nubian people lived who would have to be resettled. In the end Sudan's land near the area of Lake Nasser was mostly flooded by the lake.
The Great Man-Made River is a network of pipes that supplies fresh water obtained from the Nubian Sandstone Aquifer System fossil aquifer across Libya. It is the world's largest irrigation project. The project utilizes a pipeline system that pumps water from the Nubian Sandstone Aquifer System from down south in Libya to cities in the populous Libyan northern Mediterranean coast including Tripoli and Benghazi. The water covers a distance of up to 1,600 kilometers and provides 70% of all freshwater used in Libya.
Fossil water or paleowater is an ancient body of water that has been contained in some undisturbed space, typically groundwater in an aquifer, for millennia. Other types of fossil water can include subglacial lakes, such as Antarctica's Lake Vostok, and even ancient water on other planets.
The Waterloo Moraine is a landform and sediment body that was created as a moraine in the Regional Municipality of Waterloo, in Ontario, Canada. It covers a large portion of the cities of Waterloo and Kitchener and the township of Wilmot, and some parts of the townships of Wellesley and North Dumfries. About 90% of the water supply of the Regional Municipality of Waterloo is derived from groundwater of the Waterloo Moraine aquifer system.
The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Located on the eastern edge of the Edwards Plateau in the U.S. state of Texas, it is the source of drinking water for two million people, and is the primary water supply for agriculture and industry in the aquifer's region. Additionally, the Edwards Aquifer feeds the Comal and San Marcos Springs, provides springflow for recreational and downstream uses in the Nueces, San Antonio, Guadalupe, and San Marcos river basins, and is home to several unique and endangered species.
The Guarani Aquifer, located beneath the surface of Argentina, Brazil, Paraguay, and Uruguay, is the second largest known aquifer system in the world and is an important source of fresh water. Named after the Guarani people, it covers 1,200,000 square kilometres (460,000 sq mi), with a volume of about 40,000 cubic kilometres (9,600 cu mi), a thickness of between 50 metres (160 ft) and 800 metres (2,600 ft) and a maximum depth of about 1,800 metres (5,900 ft). It is estimated to contain about 37,000 cubic kilometres (8,900 cu mi) of water, with a total recharge rate of about 166 km³/year from precipitation. It is said that this vast underground reservoir could supply fresh drinking water to the world for 200 years. However, at closer inspection, if the world population were to stay at an equilibrium of about 6.96 billion, not even taking into account that babies need less water than grown adults, this figure reaches 1600 years, allowing about 9 liters per day per person. Due to an expected shortage of fresh water on a global scale, which environmentalists suggest will become critical in under 20 years, this important natural resource is rapidly becoming politicised, and its control becomes ever more controversial.
Groundwater recharge or deep drainage or deep percolation is a hydrologic process, where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. This process usually occurs in the vadose zone below plant roots and is often expressed as a flux to the water table surface. Groundwater recharge also encompasses water moving away from the water table farther into the saturated zone. Recharge occurs both naturally and through anthropogenic processes, where rainwater and or reclaimed water is routed to the subsurface.
A sabkha is a coastal, supratidal mudflat or sandflat in which evaporite-saline minerals accumulate as the result of semiarid to arid climate. Sabkhas are gradational between land and intertidal zone within restricted coastal plains just above normal high-tide level. Within a sabkha, evaporite-saline minerals sediments typically accumulate below the surface of mudflats or sandflats. Evaporite-saline minerals, tidal-flood, and aeolian deposits characterize many sabkhas found along modern coastlines. The accepted type locality for a sabkha is at the southern coast of the Persian Gulf, in the United Arab Emirates. Evidence of clastic sabkhas are found in the geological record of many areas, including the UK and Ireland. Sabkha is a phonetic transliteration of the Arabic word used to describe any form of salt flat. A sabkha is also known as a sabkhah,sebkha, or coastal sabkha.
Overdrafting is the process of extracting groundwater beyond the equilibrium yield of an aquifer. Groundwater is one of the largest sources of fresh water and is found underground. The primary cause of groundwater depletion is the excessive pumping of groundwater up from underground aquifers.
The Nubian Sandstone is a variety of sedimentary rock deposited on the Precambrian basement in the eastern Sahara, north-east Africa and Arabian Peninsula. It consists of continental sandstone with thin beds of marine limestones, and marls. The Nubian Sandstone was deposited between the Lower Paleozoic and Upper Cretaceous, with marine beds dating from the Carboniferous to Lower Cretaceous.
The water resources management system in Uruguay has been influenced by the general sense of water as an abundant resource in the country. Average annual rainfall is 1,182 mm, representing a contribution of 210 km3 annually throughout its territory. In 2002, the per capita renewable water resources was 41,065 cubic meters, way above the world average 8,467 m3 in 2006. Uruguay also shares one of the largest groundwater reserves in the world, the Guarani Aquifer, with Brazil, Argentina, Paraguay. The Guarani aquifer covers 1,200,000 square kilometers and has a storage capacity of 40,000 km3.
Water resources management (WRM) functions in Argentina are handled by multiple institutions operating at the national, provincial, and river basin level, with a variety of functions and jurisdictions. On the national level, the National Institute for Water and the Environment (INA) and the National Water and Sanitation Utility (AySA) are charged with the duties of researching, water resources preservation, developing services, and implementing water projects.
Water resources management in modern Egypt, is a complex process that involves multiple stakeholders who use water for irrigation, municipal and industrial water supply, hydropower generation and navigation. In addition, the waters of the Nile support aquatic ecosystems that are threatened by abstraction and pollution. Egypt also has substantial fossil groundwater resources in the Western Desert.
The Saginaw Aquifer is a bedrock aquifer located in central Michigan in the United States. It is part of an aquifer system found in Mississippian or younger stratigraphic units in the Michigan Basin. The aquifer covers approximately 11,000 square miles (28,000 km2) and is estimated to contain 4 cubic miles (17 km3) of water, approximately 50 feet (15 m) to 400 feet (120 m) underground.
Borrego Valley Groundwater Basin, located in the very southern region of California, is one of the driest basins in the state. With climate change predicted to have strong effects into foreseeable future, the region is viewed with a skepticism in the sustainable use of water at current rates of consumption. Both natural and man-made geographic divisions within this basin allow for a closer inspection of the various management techniques implemented throughout the years, and provide a basis for what may be pursued for an uncertain future.
Coastal Hydrogeology is a branch of Hydrogeology that focuses on the movement and the chemical properties of groundwater in coastal areas. Coastal Hydrogeology studies the interaction between fresh groundwater and seawater, including seawater intrusion, sea level induced groundwater level fluctuation, submarine groundwater discharge, human activities and groundwater management in coastal areas.
The International Campaign to Save the Monuments of Nubia was the relocation of 22 monuments in Lower Nubia, in Southern Egypt and northern Sudan, between 1960 and 1980. The success of the project, in particular the creation of a coalition of 50 countries behind the project, led to the creation of the World Heritage Convention in 1972, and thus to the modern system of World Heritage Sites.
