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.
Resource depletion is the consumption of a resource faster than it can be replenished. Natural resources are commonly divided between renewable resources and non-renewable resources. The use of either of these forms of resources beyond their rate of replacement is considered to be resource depletion. The value of a resource is a direct result of its availability in nature and the cost of extracting the resource. The more a resource is depleted the more the value of the resource increases. There are several types of resource depletion, including but not limited to: mining for fossil fuels and minerals, deforestation, pollution or contamination of resources, wetland and ecosystem degradation, soil erosion, overconsumption, aquifer depletion, and the excessive or unnecessary use of resources. Resource depletion is most commonly used in reference to farming, fishing, mining, water usage, and the consumption of fossil fuels. Depletion of wildlife populations is called defaunation.
Water extraction is the process of taking water from any source, either temporarily or permanently, for flood control or to obtain water for, for example, irrigation. The extracted water could also be used as drinking water after suitable treatment.
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 Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells.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.
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.
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. Insufficient recharge can lead to depletion, reducing the usefulness of the aquifer for humans. Depletion can also have impacts on the environment around the aquifer, such as soil compression and land subsidence, local climatic change, soil chemistry changes, and other deterioration of the local environment.
Surface water is water located on top of land, forming terrestrial waterbodies, and may also be referred to as blue water, opposed to the seawater and waterbodies like the ocean.
Water supply and sanitation in Saudi Arabia is characterized by challenges and achievements. One of the main challenges is water scarcity. In order to overcome water scarcity, substantial investments have been undertaken in seawater desalination, water distribution, sewerage and wastewater treatment. Today about 50% of drinking water comes from desalination, 40% from the mining of non-renewable groundwater and only 10% from surface water in the mountainous southwest of the country. The capital Riyadh, located in the heart of the country, is supplied with desalinated water pumped from the Persian Gulf over a distance of 467 km. Water is provided almost for free to residential users. Despite improvements, service quality remains poor, for example in terms of continuity of supply. Another challenge is weak institutional capacity and governance, reflecting general characteristics of the public sector in Saudi Arabia. Among the achievements is a significant increases in desalination, and in access to water, the expansion of wastewater treatment, as well as the use of treated effluent for the irrigation of urban green spaces, and for agriculture.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity. Physical water scarcity is where there is not enough water to meet all demands. This includes water needed for ecosystems to function. Regions with a desert climate often face physical water scarcity. Central Asia, West Asia, and North Africa are examples of arid areas. Economic water scarcity results from a lack of investment in infrastructure or technology to draw water from rivers, aquifers, or other water sources. It also results from weak human capacity to meet water demand. Many people in Sub-Saharan Africa are living with economic water scarcity.
Water resources are natural resources of water that are potentially useful for humans, for example as a source of drinking water supply or irrigation water. 97% of the water on Earth is salt water and only three percent is fresh water; slightly over two-thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air. Natural sources of fresh water include surface water, under river flow, groundwater and frozen water. Non-natural or human-made sources of fresh water can include wastewater that has been treated for reuse options, and desalinated seawater. People use water resources for agricultural, industrial and household activities.
Water supply and sanitation in Israel are intricately linked to the historical development of Israel. Because rain falls only in the winter, and largely in the northern part of the country, irrigation and water engineering are considered vital to the country's economic survival and growth. Large scale projects to desalinate seawater, direct water from rivers and reservoirs in the north, make optimal use of groundwater, and reclaim flood overflow and sewage have been undertaken. Among them is the National Water Carrier, carrying water from the country's biggest freshwater lake, the Sea of Galilee, to the northern part of the Negev desert through channels, pipes and tunnels. Israel's water demand today outstrips available conventional water resources. Thus, in an average year, Israel relies for about half of its water supply on unconventional water resources, including reclaimed water and desalination. A particularly long drought in 1998–2002 had prompted the government to promote large-scale seawater desalination. In 2022, 85% of the country's drinkable water was produced through desalination of saltwater and brackish water.
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 Syria is confronted with numerous challenges. First, all of the country's major rivers are shared with neighboring countries, and Syria depends to a large extent on the inflow of water from Turkey through the Euphrates and its tributaries. Second, high population growth and urbanisation increase the pressure on water resources, resulting in localized groundwater depletion and pollution, for example in the Ghouta near Damascus. Third, there is no legal framework for integrated water resources management. Finally, the institutions in charge of water resources management are weak, being both highly centralized and fragmented between sectors, and they often lack the power to enforce regulations. Water resources policies have been focused on the construction of dams, the development of irrigated agriculture and occasional interbasin transfers, such as a pipeline to supply drinking water to Aleppo from the Euphrates. There are 165 dams in Syria with a total storage capacity of 19.6 km3. Demand management through metering, higher tariffs, more efficient irrigation technologies and the reduction of non-revenue water in drinking water supply has received less emphasis than supply management. The government implements a large program for the construction of wastewater treatment plants including the use of reclaimed water for irrigation.
The three cities of Abu Dhabi Emirate within the United Arab Emirates – the coastal city Abu Dhabi itself as well as the inland oases Al Ain and Liwa – receive their drinking water supply entirely from desalinated seawater.
Water scarcity in Iran is caused by high climatic variability, uneven distribution of water, over exploitation of available water resources,and prioritization of economic development. Water scarcity in Iran is further exacerbated by climate change.
The State of Israel is one of the smallest countries in the world, around 20,000 sq. km, and has relatively few natural resources. Due to its limited space, semi-arid climate, high population growth and resource scarcity, Israel is highly susceptible to environmental crises. These include water shortages and pollution, shrinking of the Dead Sea, waste production and disposal, air pollution and population density. As a result, resource development, in particular water, has benefited from relatively high government support throughout most of the country's history. For example, Israel's water conservation and reclamation infrastructure is one of the most advanced in the world, with approximately half its water supply derived from reclaimed and treated waste water, brackish water and desalinated water.
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include non-salty mineral-rich waters such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes. Fresh water is the water resource that is of the most and immediate use to humans.
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