Threats to Rivers

Riverside forest at sunset in Manuripi National Wildlife Reserve, Pando, Bolivia.  rel=
Riverside forest at sunset in Manuripi National Wildlife Reserve, Pando, Bolivia.
© WWF-Canon / Eduardo RUIZ

Threats to rivers are on the rise...

The main threats to river basins (the entire area drained by a river) continue to mount.
Construction of large dams and physical alterations of river flow by straightening and deepening of river courses.
This disrupts the natural flooding cycles, reduces flows, drains wetlands, cuts rivers off from their floodplains, and inundates riparian habitats, resulting in the destruction of species, the intensification of floods and a threat to livelihoods in the long term.
 / ©: WWF-Canon / Michel GUNTHER
China's Three Gorges Dam caused the forcible resettlement of 1.3 million people and destroyed the habitat of endangered aquatic species.
© WWF-Canon / Michel GUNTHER
Deforestation and loss of natural habitats including wetlands - source of abundant goods and services for society - for urban, industrial or agricultural use. This reduces natural flood control and destroys the habitats used by fish, waterbirds and many other species for breeding, feeding and migrating.
São João  River Basin Management project,  part of one of the WWF Freshwater projects sponsored by ... / ©: WWF-Canon / Edward PARKER
A view of the São João River which demonstrates the many problems of its management- deforestation, canalisation, sand extraction and conversion to ranching. São João River Basin Management project, part of one of the WWF Freshwater projects sponsored by HSBC. Rio de Janeiro State, Brazil
© WWF-Canon / Edward PARKER
Excessive water abstraction for agricultural irrigation, domestic consumption and urban/industrial use.
This may involve pumping too much water from underground supplies, or long distance transfers of water from one basin to a neighbouring river basin. In both cases, the result has often been the same story of dried-up river beds and wetlands irreparable damage to wildlife, and failure to deliver overall economic benefits. Sadly, the ecological and economic value of freshwater systems damaged or destroyed by such 'technical fixes' are seldom taken properly into account.
Irrigating sugar cane fields. Kafue Flats, Zambia  / ©: WWF-Canon / Martin HARVEY
Irrigating sugar cane fields. Sugar cane farms rely heavily on water from the Kafue River for irrigation, and effluents from sugar-cane processing are discharged back into the river. Rich in nutrients this causes plant growth (Water hyacinth) which clogs up waterways. Local people have problems navigating the river and fish suffocate. Kafue Flats, Zambia
© WWF-Canon / Martin HARVEY
Pollution, caused by runoff from agricultural chemicals, poorly-managed and sometimes out-of-date industrial processes, and lack of adequate treatment for sewage and other urban waste. The results may include water that is unfit to drink, massive fish kills, and complete loss of underwater plants. Yet many effects of pollution are more insidious, only becoming clear after toxic substances have been building up in the food chain for many years.
Sewage pipe spewing pollution from a factory directly into a river near Mumbai (Bombay). India. / ©: WWF-Canon / Mauri RAUTKARI
Sewage pipe spewing pollution from a factory directly into a river near Mumbai (Bombay). India.
© WWF-Canon / Mauri RAUTKARI
Long-term changes in rainfall, river flow and underground water supplies due to climate change.
For example, some river basins are expected to experience increased flooding, whilst others may become progressively drier. These changes - often aggravated by short-sighted land-use planning - are affecting all sectors of human society, and will have far-reaching consequences for freshwater biodiversity. Most projections show that the rate and scale of these impacts are only set to grow.
Flooding of river Main  Inundations caused by heavy rain and destruction of floodplain.  Frankfurt ... / ©: WWF-Canon / Hartmut JUNGIUS
Flooding of river Main Inundations caused by heavy rain and destruction of floodplain. Frankfurt am Main, Germany.
© WWF-Canon / Hartmut JUNGIUS

People and environment suffer when rivers are poorly managed

All this is conspiring to unravel the ecological functioning of the world's river basins, in effect destroying the very systems that gather and convey freshwater for life.

Dynamic, living systems
Experts agree that the best approach to conserving the world's freshwater resources is through managing river basins sustainably. This means making wise choices about resource use, based on an understanding of how to maintain dynamic, living systems in the long term.

Knock-on effects
Any activity that takes place in a river basin such as the disposal of waste water or the cutting of forests, has impacts downstream. A vivid example of this was the cyanide spill in the River Tisza (a tributary of the Danube) from a mine in Romania in January 2000. The highly toxic chemical swept downstream through Hungary, devastating aquatic life along the course of the river and contaminating the drinking water of hundreds of thousands of people.

Source of life, food and power
River basins are important from hydrological, economic and ecological points of view. They absorb and channel the run-off from snow-melt and rainfall which, when wisely managed, can provide fresh drinking water as well as access to food, hydropower, building materials (e.g. reeds for thatching), medicines and recreational opportunities.

Critical passages
They also form a critical link between land and sea, providing transportation routes for people, and making it possible for fish to migrate between marine and freshwater systems.

Purifying water
By acting as natural 'filters' and 'sponges', well-managed basins play a vital role in water purification, water retention and regulation of flood peaks. In many parts of the world, seasonal flooding remains the key to maintaining fertility for grazing and agriculture.

Mix of habitats = mix of life
Last but not least, these often very large-scale ecosystems combine both terrestrial and aquatic components, thereby providing a wide diversity of habitats for plants and animals.

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