Freshwater

Freshwater
M M from Switzerland · CC BY-SA 2.0 · source
Name	Freshwater
Caption	Freshwater habitat
Type	Natural resource
Location	Global
Area	Variable
Status	Vital

Freshwater is water with low concentrations of dissolved salts that supports terrestrial life and human societies. It occurs in rivers, lakes, streams, wetlands, glaciers, and groundwater and underpins infrastructure, agriculture, industry, and culture across regions such as Amazon Basin, Great Lakes, Congo Basin, Ganges Delta, and Mekong River. Freshwater systems are studied by institutions like United Nations Environment Programme, World Health Organization, International Union for Conservation of Nature, and universities including University of Oxford, Stanford University, University of Cape Town, and Peking University.

Definition and Characteristics

Freshwater is defined by salinity thresholds used by agencies such as United States Geological Survey, European Environment Agency, Food and Agriculture Organization, United Nations Educational, Scientific and Cultural Organization and standards like those of World Meteorological Organization; physicochemical traits include parameters monitored by American Public Health Association, International Organization for Standardization, Environmental Protection Agency, and laboratories at Massachusetts Institute of Technology and Max Planck Society. Key measurable properties—temperature, turbidity, dissolved oxygen, pH, conductivity—are assessed with equipment from manufacturers like Hach Company and Thermo Fisher Scientific and reported in databases maintained by Global Runoff Data Centre and Global Water Partnership.

Distribution and Types

Freshwater occurs in continental systems such as the Nile, Yangtze River, Mississippi River, Danube, Volga River, and regions like the Himalayas, Andes, Rocky Mountains, Alps, and Great Rift Valley. Types include lotic systems exemplified by the Amazon River Basin and lentic systems exemplified by Lake Baikal, Lake Superior, Lake Victoria, and temporary wetlands like those in the Okavango Delta. Cryospheric freshwater is stored in glaciers such as the Greenland ice sheet and Antarctic ice sheet and in mountain glaciers of Karakoram. Groundwater aquifers include the Great Artesian Basin, Ogallala Aquifer, and Nubian Sandstone Aquifer as mapped by agencies like US Geological Survey and British Geological Survey.

Hydrology and Watershed Processes

Hydrological processes are examined in models developed by Hydrologic Engineering Center, European Centre for Medium-Range Weather Forecasts, Intergovernmental Panel on Climate Change, and research groups at Imperial College London and ETH Zurich. Watershed dynamics are influenced by precipitation patterns from El Niño–Southern Oscillation, Indian Ocean Dipole, and the North Atlantic Oscillation; runoff, infiltration, evapotranspiration, and storage are managed using frameworks from International Commission on Large Dams, World Meteorological Organization, FAO AQUASTAT, and river basin authorities like the Mekong River Commission and Nile Basin Initiative.

Ecology and Biodiversity

Freshwater ecosystems host taxa documented in works by Charles Darwin-inspired collections and modern inventories at Smithsonian Institution, Natural History Museum, London, American Museum of Natural History, and Royal Botanic Gardens, Kew. Iconic species inhabit rivers and lakes: fish faunas in Amazon Basin and Congo Basin; amphibians catalogued by IUCN Red List; macroinvertebrates studied via protocols from Society for Freshwater Science; and wetland plants recorded by Ramsar Convention lists. Biodiversity threats and keystone species have been the focus of projects by Conservation International, World Wildlife Fund, The Nature Conservancy, and research at California Academy of Sciences.

Human Use and Management

Human reliance on freshwater is institutionalized through utilities and projects run by Metropolitan Water District of Southern California, Thames Water, Suez Group, Veolia Environnement, and agencies like US Bureau of Reclamation and China Three Gorges Corporation. Uses include irrigation in projects influenced by Green Revolution technologies and staples such as rice farming in the Ganges Delta and maize in the Central Valley (California). Urban water supply, sanitation, and delivery are governed by standards from WHO, UNICEF, and initiatives like Clean Water Act-era programs in the United States and urban planning at City of Tokyo and Singapore Public Utilities Board.

Threats and Conservation

Threats—pollution events like incidents investigated by Environmental Protection Agency, eutrophication documented in Lake Erie, invasive species such as Asian carp and Zebra mussel, over-extraction of aquifers like the Ogallala Aquifer, and climate impacts chronicled by the Intergovernmental Panel on Climate Change—are addressed by conservation groups including Ramsar Convention, IUCN, BirdLife International, and regional NGOs. Restoration efforts use approaches from Ecosystem-based adaptation pilots, catchment management by the Murray-Darling Basin Authority, and rewilding experiments associated with organizations like Rewilding Europe.

Policy, Law, and Governance

Legal and governance frameworks include multilateral treaties and institutions: Ramsar Convention on Wetlands, United Nations Watercourses Convention, Convention on Biological Diversity, and regional agreements like the Danube River Protection Convention and Indus Waters Treaty. National laws and courts—from rulings in the Supreme Court of India to legislation such as the Clean Water Act in the United States—shape allocation and rights managed by bodies like European Commission, African Ministers' Council on Water, Asian Development Bank, and World Bank. International finance and capacity-building programs by Global Environment Facility, Green Climate Fund, and United Nations Development Programme support integrated water resources management undertaken by entities such as IWMI and UN-Water.

Category:Hydrology