The geography of Egypt relates to two regions: North Africa and Southwest Asia.
The Niger River is the main river of West Africa, extending about 4,180 km (2,600 mi). Its drainage basin is 2,117,700 km2 (817,600 sq mi) in area. Its source is in the Guinea Highlands in southeastern Guinea near the Sierra Leone border. It runs in a crescent through Mali, Niger, on the border with Benin and then through Nigeria, discharging through a massive delta, known as the Niger Delta, into the Gulf of Guinea in the Atlantic Ocean. The Niger is the third-longest river in Africa, exceeded only by the Nile and the Congo River. Its main tributary is the Benue River.
Irrigation is the agricultural process of applying controlled amounts of water to land to assist in the production of crops, as well as to grow landscape plants and lawns, where it may be known as watering. Agriculture that does not use irrigation but instead relies only on direct rainfall is referred to as rain-fed. Irrigation has been a central feature of agriculture for over 5,000 years and has been developed independently by many cultures across the globe.
Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean. It can also come about through artificial processes such as irrigation and road salt.
The Kura is an east-flowing river south of the Greater Caucasus Mountains which drains the southern slopes of the Greater Caucasus east into the Caspian Sea. It also drains the north side of the Lesser Caucasus while its main tributary, the Aras, drains the south side of those mountains. Starting in northeastern Turkey, it flows through Turkey to Georgia, then to Azerbaijan, where it receives the Aras as a right tributary, and enters the Caspian Sea at Neftçala. The total length of the river is 1,515 kilometres (941 mi).
The Gunnison River is located in western Colorado, and it is one of the largest tributaries of the Colorado river. The 180-mile (289-km) long river flows east to west, and it has a drainage area of 7,923 square miles (20,520 km2) according to the USGS. The drainage basin of the Gunnison River collects water from different habitats, such as forests and alpine meadows, located the along Continental Divide. As the river flows westward, it carves through the San Juan Mountains. It flows into the Colorado River at Grand Junction.
The Sacramento–San Joaquin River Delta, or California Delta, is an expansive inland river delta and estuary in Northern California. The Delta is formed at the western edge of the Central Valley by the confluence of the Sacramento and San Joaquin rivers and lies just east of where the rivers enter Suisun Bay, which flows into San Francisco Bay and then the Pacific Ocean via San Pablo Bay. The Delta is recognized for protection by the California Bays and Estuaries Policy. Sacramento–San Joaquin Delta was designated a National Heritage Area on March 12, 2019. The city of Stockton is located on the San Joaquin River on the eastern edge of the delta. The total area of the Delta, including both land and water, is about 1,100 square miles (2,800 km2). Its population is around 500,000 residents.
An andén, Spanish for "platform", is a stair-step like terrace dug into the slope of a hillside for agricultural purposes. The term is most often used to refer to the terraces built by pre-Columbian cultures in the Andes mountains of South America. Andenes had several functions, the most important of which was to increase the amount of cultivatable land available to farmers by leveling a planting area for crops. The best known examples of andenes are in Peru, especially in the Sacred Valley near the Inca capital of Cuzco and in the Colca Canyon. Many andenes have survived for more than 500 years and are still in use by farmers throughout the region.
Watertable control is the practice of controlling the height of the water table by drainage. Its main applications are in agricultural land and in cities to manage the extensive underground infrastructure that includes the foundations of large buildings, underground transit systems, and extensive utilities.
Soil salinity control relates to controlling the problem of soil salinity and reclaiming salinized agricultural land.
SaltMod is computer program for the prediction of the salinity of soil moisture, groundwater and drainage water, the depth of the watertable, and the drain discharge (hydrology) in irrigated agricultural lands, using different (geo)hydrologic conditions, varying water management options, including the use of ground water for irrigation, and several cropping rotation schedules. The water management options include irrigation, drainage, and the use of subsurface drainage water from pipe drains, ditches or wells for irrigation.
Water resources and irrigation infrastructure in Peru vary throughout the country. The coastal region, an arid but fertile land, has about two-thirds of Peru’s irrigation infrastructure due to private and public investment aimed at increasing agricultural exports. The Highlands and Amazon regions, with abundant water resources but rudimentary irrigation systems, are home to the majority of Peru's poor, many of whom rely on subsistence or small-scale farming.
While Peru accounts for about four per cent of the world's annual renewable water resources, over 98% of its water is available east of the Andes, in the Amazon region. The coastal area of Peru, with most of economic activities and more than half of the population, receives only 1.8% of the national freshwater renewable water resources. Economic and population growth are taking an increasing toll on water resources quantity and quality, especially in the coastal area of Peru.
The environmental effects of irrigation relate to the changes in quantity and quality of soil and water as a result of irrigation and the subsequent effects on natural and social conditions in river basins and downstream of an irrigation scheme. The effects stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme.
A leaching model is a hydrological model by which the leaching with irrigation water of dissolved substances, notably salt, in the soil is described depending on the hydrological regime and the soil's properties.
The model may describe the process (1) in time and (2) as a function of amount of water applied.
Leaching is often done to reclaim saline soil or to conserve a favorable salt content of the soil of irrigated land as all irrigation water contains salts.
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.
Costa Rica is divided into three major drainage basins encompassing 34 watersheds with numerous rivers and tributaries, one major lake used for hydroelectric generation, and two major aquifers that serve to store 90% of the municipal, industrial, and agricultural water supply needs of Costa Rica. Agriculture is the largest water user demanding around 53% of total supplies while the sector contributes 6.5% to the Costa Rica GDP. About a fifth of land under cultivation is being irrigated by surface water. Hydroelectric power generation makes up a significant portion of electricity usage in Costa Rica and much of this comes from the Arenal dam.
An aqueduct is a watercourse constructed to carry water from a source to a distribution point far away. In modern engineering, the term aqueduct is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose. The term aqueduct also often refers specifically to a bridge carrying an artificial watercourse. Aqueducts were used in ancient Greece, ancient Egypt, and ancient Rome. The simplest aqueducts are small ditches cut into the earth. Much larger channels may be used in modern aqueducts. Aqueducts sometimes run for some or all of their path through tunnels constructed underground. Modern aqueducts may also use pipelines. Historically, agricultural societies have constructed aqueducts to irrigate crops and supply large cities with drinking water.
Water use in alluvial fans refers to irrigation systems using the water resources in alluvial fans, mainly river floods and groundwater recharged by infiltration of rain or river water, to enhance the production of agricultural crops.
