Planèt'eau > Freshwater > 2 - Main threats to freshwaters

2 - Main threats to freshwaters

Freshwater is the single most essential good for our well-being. Less than 1% of the world's water is readily available for direct human uses : agriculture and industry, drinking and domestic purposes, and energy generation and transport. Increasing competition for water among such uses is degrading the very natural resources on which we all depend.

Climate change is compounding these effects through increased frequency of extreme weather events. Projections of trends into the future do not brighten the picture. Currently, 54 % of accessible runoff is appropriated by humans. By the year 2025, two-thirds of the world's population could be facing serious problems with water availibility. Predictions regarding freshwater biodiversity impacts over time -frame vary from disastrous to the apocalyptic.



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Sewage pipe spewing pollution from a factory directly into a river near Bombay India

2.a - Lack of sustainable agriculture

Agriculture, the largest industry in the world, is also the biggest threat to the environment. Inefficient food production and harmful agriculture subsidies are causing deforestation, water shortages and pollution.

Agriculture wastes 60% or 1,500 trillion litres, of the 2,500 trillion litres of water it uses each year - which is 70% of the world’s accessible water. Many big food producing countries like the US, China, India, Pakistan, Australia and Spain have reached or are close to reaching their renewable water resource limits.

The lack of sustainable agriculture harms the environment by sucking rivers, lakes and underground water sources dry, increasing soil salinity and thereby destroying its quality, and by washing pollutants and pesticides into rivers that in turn destroy downstream ecosystems such as corals and breeding grounds for fish in coastal areas.

The main causes are : leaky irrigation systems, wasteful field application methods, pollution by agri-chemicals and growing thirsty crops unsuited for the environment.

The waste and pollution of water is made worse by misdirected subsidies, low public and political awareness of the crisis, and weak environmental legislation.

A WWF report, "Thirsty Crops: Agricultural Water Use and River Basin Conservation", identifies cotton, rice, sugar cane and wheat as the "thirstiest" crops in nine large river basins rich in biodiversity. Together, these four crops account for 58% of the world's irrigated farmland.

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Picking strawberries near Coto Doñana National Park Coto Donana Spain

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Irrigating sugar cane fields

2.b - Infrastructures that destruct rivers

For reasons of hydropower, river navigation, irrigation and flood protection, rivers have been dammed, straightened, deepened, and cut off from the natural floodplains. The water from an entire river basin is sometimes diverted to a neighbouring river basin.

Such massive engineering schemes cause irreparable ecological damage, by disrupting the natural flooding cycles, reducing flows, draining wetlands and inundating riparian habitats, and resulting in the destruction of species, the intensification of floods, and a threat to livelihoods in the long term.

Often such schemes fail to deliver the economic benefits promised at the outset.

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Three Gorges Dam Yangtse river China

2.c - Species losses

Scientists generally acknowledge that freshwater species dependent on freshwater ecosystems are the world’s most endangered group of plants and animals. According to the WWF Living Planet Report 2006, 31% of freshwater species have disappeared between 1970 and 2003.

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Temperate and tropical species populations declined by around 30 per cent overall from 1970 to 2003

2.d - Rivers decline

The main threats to river basins (the entire area drained by a river) continue to mount.

The 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.

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.

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.

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.

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.


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Inundations damages due to the destruction of the Main floodplain Franckfurt Germany

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Problems on the Sao Joao River Rio de Janeiro State Brazil

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Children playing in polluted river Bombay India