Targets
Rio Declaration of Environment and Development (1992):
'States shall cooperate in a spirit of global partnership to conserve, protect and restore the health and integrity of the Earth's ecosystem.'
Bonn Recommendations for Action (2001):
'Water governance arrangements should protect ecosystems and preserve or restore the ecological integrity of groundwater, rivers, lakes, wetlands and associated coastal zones.'
Pressures on freshwater ecosystems
A wide range of human uses and transformations of freshwater or terrestrial environments has the potential to alter, sometimes irreversibly, the integrity of freshwater ecosystems.
| Human Activity |
Potential Impact |
Function at Risk |
| Population and consumption growth |
Increases water abstraction and acquisition of cultivated land through wetland drainage. Increases requirement for all other activities with consequent risks |
Vitually all ecosystem functions including habitat, production and regulation functions |
| Infrastructure development (dams, dikes, levees, diversions etc) |
Loss of integrity alters timing and quantity of river flows, water temperature, nutrient and sediment transport and thus delta replenishment, blocks fish migrations |
Water quantity and quality, habitats, floodplain fertility, fisheries, delta economies |
| Land conversion
| Eliminates key components of aquatic environment, loss of functions; integrity , habitat & biodiversity, alters runoff patterns, inhibits natural recharge, fills water bodies with silt |
Natural flood control, habitats for fisheries and waterfowl, recreation, water supply, water quantity and quality |
| Overharvesting and exploitation |
Depletes living resources, ecosystem functions and biodiversity (groundwater depletion, fisheries collapse) |
Food production, water supply, water quality and water quantity |
| Introduction of exotic species
| Out competition of native species, alters production and nutrient cycling, loss of biodiversity |
Food production, wildlife habitat, recreation |
| Release of pollutants to land, air or water |
Pollution of water bodies alters chemistry and ecology of rivers, lakes and wetlands. Greenhouse gas emissions produce dramatic changes in runoff and rainfall patterns |
Water supply, habitat, water quality, food production. Climate change may also impact hydropower, dilution capacity, transport, flood control |
[Source]: Extracted form the Executive Summary of the WWDR. IUCN, 2000. Vision for Water and Nature. A World Strategy for Conservation and Sustainable Management of Water Resources in the 21st Century - Compilation of All Project Documents. Cambridge.
Main threats to ecosystems from human activities
- Population and consumption growth.
- Infrastructure development (dams, urban growth, highways).
- Land conversion (deforestation, agriculture, urban growth).
- Overharvesting and overexploitation (overfishing, wasteful irrigation).
- Release of pollutants (human waste, agricultural and industrial chemicals).
- Introduction of exotic species (replacing and overwhelming indigenous species).
River pollution
Every day, 2 million tons of human waste are disposed of in water courses.
- 40% of water bodies assessed in 1998 in the United States were not deemed fit for
World distribution of hydropower recreational use due to nutrient, metal and agricultural pollution.
- 5 out of 55 rivers in Europe are considered pristine, and only the upper sections of the 14 largest rivers retain 'good ecological status'.
- In Asia, all rivers running through cities are badly polluted.
Impacts of waterways diversion and fragmentation
- 60% of the world's 227 largest rivers are severely fragmented by dams, diversions and canals, leading to the degradation of ecosystems.
- In 1998, the Aral Sea had lost 75% of its total volume. Its demise was caused primarily by the diversion of the inflowing Amu Darya and Syr Darya rivers.
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Wetlands loss:
- 50% of the world's wetlands have been lost since 1900.
- More than 80% of the wetlands along the Danube River have been destroyed since the start of the 20th century.
- The Mesopotamian Marshlands in the Tigris and Euphrates river basins were devastated by damming and river channelisation.
Biodiversity loss:
- Between 34 and 80 fish species have become extinct since the late 19th century, 6 since 1970.
- At a global level, around 24% of mammals and 12% of birds are classified as threatened.
- In the United States, 120 of 822 freshwater fish species are considered threatened, representing 15% of total fish species.
Definitions
Ecosystem: a dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit.
Wetlands: areas of marsh, fen, peatland or water.
Ramsar Convention: international convention protecting wetland areas. |
Most of this information is based on figures provided by the United Nations Environment Programme (UNEP).
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UNESCO.ORG
