Secure water supplies are needed to support irrigation and food production, manufacturing and energy generation. However, the use of water resources can lead to various problems. E.g. the depletion of underground aquifers and salinization of the soil.
case study: the aral sea
Location: north-western part of Uzbekistan and southern Kazakhstan
Background: Formerly, one of the four largest inland sea, with an area of 68,000 square kilometres, the Aral Sea has been steadily shrinking since the 1960s. By 2007, the sea had declines to just 10% of its original size and split into separate lakes.
Causes:
- In the late 1950s, the Soviet government diverted much of the water from the rivers Amu Darya and Syr Darya, which fed into the Aral Sea, for irrigation of agriculture.
- In the early 1960’s, the Soviet central government decided to make the Soviet Union self-sufficient in cotton and increase rice production. Government officials ordered the additional amount of needed water to be taken from the two rivers that feed the Aral Large dams were built across both rivers, and an 850-mile central canal with a far-reaching system of “feeder” canals was created.
Impacts:
- Over 30 years, the Aral Sea experienced a severe drop in water level, its shoreline receded, and its salt content increased. The water level has dropped by 16 metres and the volume has been reduced by 75%.
- The marine environment became hostile to the sea life in it, killing the plants and animals. As the marine life died, the fishing industry suffered. All 20 known fish species in the Aral Sea are now extinct, unable to survive the toxic, salty
- The sea has shrunk to two-fifths of its original size and now ranks about 10th in the
- Drinking water supplies have dwindled, and the water is contaminated with pesticides and other agricultural chemicals as well as bacteria and
- Highly toxic pesticides and other harmful chemicals are blown from the dried-up sea creating dust containing these toxic
- As the Aral Sea has lost water, the climate has become more
- Respiratory illnesses including tuberculosis and cancer, digestive disorders and infectious diseases are common ailments in the
- There is a high child mortality rate of 75 in every 1,000 new-borns and maternity death of 12 in every 1,000
- The Aral Sea fishing industry, which use to employ 40,000 and reportedly produced one- sixth of the Soviet Union’s entire fish catch, has been
The stakeholders involved:
- The former soviet government – began the irrigation scheme designed to develop fruit and cotton farming in an unproductive region and create jobs for millions of farm workers.
- Fishing community – use to be a prosperous industry that employed 60,000 people but now huge unemployment and economic hardships have occurred.
- Local residents – health problems caused by wind-blown salt and dust from the dried-out sea bed. Drinking water and ports of remaining sea have become heavily polluted from weapons testing, industrial projects, and pesticide and fertiliser run of. Among highest infant mortality rates in the world, 10% of children dying in their first year mainly due to kidney and heart failure.
- Uzbekistan government – irrigation schemes based on the Aral Sea allow this poor country with few resources to remained one of the world’s largest exports of cotton. Hopes to discover oil deposits beneath dry sea best.
- Scientists – climate has now changed (making area more prone to greater extremes of temperature and more arid) and extinction of species in the area: 160/360 bird species and 32/70 mammal species and few of the 24 fish species remain.
- Kazakhstan farmers – irrigation has brought water table to the surface, making drinking water and food crops salty and polluted.
- International economists – people can no longer feed themselves as the land is infertile, could create 10 million environmental
- Water engineers – inspections have revealed that many of the irrigation canals were poorly built, allowing water to leak out or evaporate. The main Kara Kum Cana, largest in central Asia, allows 30-75% of its water to go to waste.
case study: california environment at risk
The Colorado River Delta
- The river used to flow into the Gulf of California in northern Mexico forming a delta.
- However, since the building of the Hoover and Glen Canyon Dams upstream, the flow of Colorado has been so reduced that the delta has been massively degraded and almost 2 million acres of riversides habitats have dried up.
The Sacramento-San Joaquin River delta
- Half a million people live around the 60 low lying islands of the Bay delta.
- Years of neglect have allowed levees protecting the area from flooding to decay.
- Almost half of California’s annual runoff flows through this delta and 2/3rds of the state’s population depend on it for their water supplies.
Problems:
- Old, poorly maintained man-made levees and river banks along the Feather river have allowed salty water to submerge some of the islands and reduce water quality for all users and habitats.
- Several species of fish are on the endangers list – the migratory paths of salmon and smelt are blocked at Stockton on the San Joaquin when fresh water oxygen levels ae too lower. The big water pumps for the SWP also sick in a lot of fish.
- Pumping is stopped 3-4 times a year to allow fish stocks to recover.
- Water treatment works discharge chlorine into these rivers, and the build-up of trihalomethanes (suspected to cause cancers) as a result means that safe water supplies cannot be guaranteed.
The Salton Sea
- Receives runoff from irrigated farmland.
- Formed when canal banks collapsed in 1905, allowing the Colorado river to fill a natural hollow with water.
- This created a large lake covering 37 square miles, which became a wildlife refuge boasting millions of birds, fish and flora amount its fresh and salt water marshes.
- Also attracts half a million tourists a year and developing a thriving community.
Threats:
- 75% of its inflow is from cotton, citrus and sugar beet farms in the Imperial and Coachella valleys with a toxic mix of pesticide, fertilisers, defoliant and nutrients.
- High evaporation rates mean that the salt content here is 25% higher than in the Pacific Ocean.
- High salinity, algal blooms and eutrophication are thought to have caused the deaths of millions of birds and fish.
- The New River brings industrial pollutants and sewage from Mexicali in Mexico.
- The land of the Cahuilla Tribe is at risk from the deoxygenate and poor-quality water, increasing salinity and reduced fish stocks.
- Tourists have stopped visiting because of the high salt content, the stench of decay and the perception that the sea is a toxic waste dump.