Interbasin transfer

An interbasin transfer is a transfer of water from one river basin to another. The purpose of an interbasin transfer typically is to alleviate shortages in a deficit basin by transferring water from a surplus basin. Their importance is expected to increase due to population growth, increased water demand for irrigation, industry and municipal water supply, as well as because of increased hydrological variability caused by climate change. Interbasin transfers are often large and expensive, involving major infrastructure and the massive use of energy for pumping. They are also complicated in legal terms, since water rights are affected, especially if the basin of origin is a transboundary river. Finally, transfers often have significant negative environmental impacts on aquatic ecosystems.

In some cases the purpose of the transfer is not the alleviation of water scarcity. For example, the purpose of the Nam Theun II interbasin transfer in Laos is the generation of hydropower by transferring water from a higher-lying basin to a neighboring lower-lying basin. And the purpose of the Chicago Sanitary and Ship Canal is the diversion of polluted water away from Lake Michigan to the Mississippi River.

Existing transfers

For the alleviation of water scarcity:

• The California State Water Project transferring water from Northern to Southern California. It includes the California Aqueduct and the Edmonston Pumping Plant, which lifts water nearly 2,000 feet (600 meters) up and over the Tehachapi Mountains through 10 miles of tunnels for municipal water supply in the Los Angeles Metropolitan area.
• From the Colorado River to the Imperial Irrigation District in Southern California
• The National Water Carrier in Israel, transferring water from the Sea of Galilee (Jordan River Basin) to the Mediterranean coast lifting water over 372 meters. Its water is used both in agriculture and for municipal water supply.
• The Cutzamala System, transferring water from the Cutzamala River to Mexico City for use as drinking water, lifting it over more than 1000 meters. It utilizes 7 reservoirs, a 127 km long aqueduct with 21 km of tunnels, 7.5 km open canal, and a water treatment plant. Its cost was US$ 1.3 billion. See also Water resources management in Mexico
• Various transfers from the Ebro River in Spain, which flows to the Mediterranean, to basins draining to the Atlantic, such as Ebro-Besaya transfer of 1982 to supply the industrial area of Torrelavega, the Cerneja-Ordunte transfer to the Bilbao Metropolitan area of 1961, as well as the Zadorra-Arratia transfer that also supplies Bilbao through the Barazar waterfall (Source:Spanish Wikipedia article on the Ebro River)
• The Mahaweli Ganga Project in Sri Lanka includes several inter basin transfers.
• Irtysh Karganda scheme in central Kazakhistan is about 450 km long with a maximum capacity of 75 cubic meters per second. It involves a lift of 14 to 22 m.
• The Barnard River Scheme in Australia

The Central Arizona Project (CAP) in the USA is not an interbasin transfer per se, although it shares many characteristics with interbasin transfers as it transports large amounts of water over a long distance and difference in altitude. The CAP transfers water from the Colorado River to Central Arizona for both agriculture and municipal water supply to substitute for depleted groundwater. However, the water remains within the watershed of the Colorado River.

Characteristics of major existing interbasin transfers and other large-scale water trasfers to alleviate water scarcity

	Year of construction	Length	Capacity (Million cubic meters/year)	Costs (US$ bn)
California State Water Project	Eearly 1960s-1990s	715km	25 (10,300 cubic feet/sec)	5.2
Central Arizona Project	1973-93	541km	5 (1.5m acre-feet/year)	3.6
National Water Carrier	1953-64	130km	1.7	?
Cutzamala System (Mexico)	Late 1970s-late 1990s	154km	2.1 (24 m3/sec)	1.3

Transfers for the generation of hydropower:

• The Drakensberg Pumped Storage Scheme from the Tugela River that flows into the Indian Ocean into the Vaal River in South Africa, which ultimately drains into the Orange River and the Atlantic Ocean. Its purpose is hydropower generation
• In Canada, sixteen interbasin transfers have been implemented for hydropower development, including at Kemano, James Bay and Churchill Falls.
• The Nam Theun II Project in Laos, whose purpose is hydropower generation
• The Bheri-Babai Multipurpose Project on the Ghaghara River in India (Hydropower and irrigation)

Transfers for other purposes

• The Chicago Sanitary and Ship Canal in the USA

Transfers under construction

From the Yangtse River to the Yellow River and Beijing as part of the South-North Water Transfer Project in China

Proposed transfers

• Linking the Godavari-Krishna-Pennar-Cauvery Rivers in India
• From the Chalakudy River to the Bharathapuzha River in Kerala, India
• From the Ubangi River in Congo to the Chari River which empties into Lake Chad.
• From the São Francisco River to four northeastern states in Brazil. See also Water resources management in Brazil.
• From Siberia to Central Asia through the Northern river reversal

Literature

• Fereidoun Ghassemi and Ian White: Inter-Basin Water Transfer, Case Studies from Australia, United States, Canada, China and India, Cambridge University Press, International Hydrology Series, 2007, ISBN-13: 9780521869690