Irrigation Dams
Michael Jolitz jolitzmw@uwec.edu 
       
Part of Water is Life, a class website on water privatization and commodification, produced by students of Geography 378 (International Environmental Problems & Policy) at the University of Wisconsin-Eau Claire, USA, Spring 2004.

 

Irrigation uses enormous amounts of water, and often wastes water. In the United States alone, 41% of water use is for irrigation. The dams that hold this water for irrigation pose many environmental problems that degrade the water supply. The purpose of this page is to show the benefits and environmental problems associated with irrigation dams, and whether they fulfill their purpose.

Erosion and Silt

The build-up of silt behind dams is reducing their water storage capacity according to the United Nations. Storage facilities are losing an average of 1% of their storage capacity annually. Scientists also think that global climate change will increase the severity of storms and worsen erosion. Many scientists believe that removal of sediment from behind dams should be a regular occurrence.

The UN Environment Program says that 60% of the water that is used for irrigation is wasted or used inefficiently, and that 50% or more of the water that is used in cities is lost through leaks and poor management.

Kariba Dam in Zambia

The building of the Kariba Dam in Zambia has created many environmental problems. The Kariba Dam is used for power generation and irrigation for industrial and institutional water supply. The towns around the area have grown considerably in recent years. This growth has caused the demand for food to rise greatly, putting pressure on the surrounding land. More and more land has to be cultivated to support the people in this area. Overgrazing and loss of soil fertility are adding to the depletion of soil.

Kariba Dam

The photo shows a large area of cultivatible land that was flooded by the Kariba Dam. The land was flooded and thousands of people resettled. A operation called Operation Noah was launched to save many of the animals that were trapped during the flooding. The dam also had a effect on the Tsetse fly population. The Tsetse fly carries the parasite Trypanosomiasis, which causes sleeping sickness, a debilitating disease for cattle and humans. There was an attempt to try to eradicate the Tsetse by spaying the insecticide DDT. This toxic chemical has reduced the species of birds and fish in the area. It has also been found in the breast milk of nursing mothers.
 
Information on Kariba Dam was taken mostly from http://www.bized.ac.uk.

Narmada Dams in India

One of the world's foremost controversies around dams is underway in India, where dams are being built on the Narmada River. One of the main global environmental/ human rights groups that fights these dams is the International Rivers Network. India has a Narmada Valley Development Program which involves the construction of 3,000 dams and would flood thousands of acres of forest and agricultural land. India's goverment says that the project would provide water to 40 million people and irrigate over 1.8 million hectares. There would be continuous irrigation here that would degrade the fertile agricultural soils. This program will also displace approximately 1.5 million people. The people that oppose this project often place themselves in danger of arrest and detention. There have been many documentations of abuse and excessive force used against opponents of the dam, even though most protests are peaceful demonstrations.

One of the dams on the Narmada named Sardar Sarovar was opposed because it would displace almost half a million people. Another is the Maheshwar Dam which would submerge some of the richest agricultural lands in the area.

 

The map above shows a few locations on the Narmada River where some of the larger dams are planned. A good place to go to read more about this project is the International Rivers Network website.

Manitoba Hydro dams in Canada

Manitoba Hydro is an example of a utility that has exploited water for hydroelectricity rather than mainly for irrigation, but the resulting problems are similar to irrigation dams. The demand for electricity is growing at a great rate and utility companies make hydroelectric power seem friendly to the environment. The Unplug Manitoba Hydro website said, "Over the last 25 years, thousands of square miles of northern forests, rivers and lakes have been flooded or made inaccessible. And now, a toxic soup of drowned trees and other vegetation lies rotting—submerged along with native communities' hopes, dreams and traditional livelihood."
The Pimickamak (Cross Lake) Cree Nation lives near the control gate that releases water. The water fluctuations from this gate cause continual bank and island erosion. The debris disrupts travel by boat and snowmobile, and makes it difficult for trappers and fishermen to feed their families, and continue practicing traditional Cree culture. This crisis has caused the Cree to have some of the highest rates of suicide of any Aboriginal reserve in Canada. Its unemployment rate is also around 95%.

The changes at this site have destroyed wildlife habitat, mammal and bird populations and aquatic plant and animal species. There has been flooding here which causes permafrost to thaw, this in turn increases shoreline erosion and siltation into the reservoir at Cross Lake. High water levels submerge vegetation, which decomposes and produces methane. Methane is a greenhouse gas that is contributing to global warming. The amounts that are produced rival those produced by fossil fuels. The decomposition process also has caused mercury from rocks and soil, to transform into the highly toxic organic methylmercury.
Most of this information about Manitoba Hydro came from Unplug Manitoba Hydro.

 
 
 
Erosion from the water of a reservoir in Manitoba has exposed five graves on Indian Lake in Manitoba.
Other Problems
 
 
In Australia, salinity in irrigation water is a major problem. The site National Action Plan for Salinity listed these problems related to salinity and drinking water:

• More than $130 million of agricultural production is lost annually from salinity.
• More than $6 million is spent every year on building maintenance related to salinity in South Australia.
• Salinity causes $9 million damage annually to roads and highways in southwestern New South Wales.
• The area of salt affected land in Western Australia is increasing at a rate of one football field per hour.
• If salinity is not effectively managed within 20 years, the salt content in Adelaide’s drinking water may exceed World Health Organization standards for desirable drinking water in two of every five days.
• Increased salinity could cause the extinction of approximately 450 species of native flora and 250 species of invertebrate water fauna in the Western Australian wheat belt. Salinity of drinking water occurs when irrigation water soaks through the soil area where the plant roots grow, adding to the existing water. The irrigation water causes the underground water table to rise, bringing salt to the surface. When the irrigated area dries and the underground water table recedes, salt is left on the surface soil. The salinity increases each time the water is irrigated.

The Three Gorges Dam in China has many problems that environmentalists assert will decrease water quality. The Three Gorges Dam is being built built for irrigation, flood control, and hydroelectric power. There are concerns that the reservoir will collect industrial pollution, farm runoff, and sewage that regularly runs downstream. Levels of E.coli bacteria have risen as the reservoir has began to fill. There are claims that the water here will be too polluted for drinking water. This is expected to also have a disastrous effect on many terrestrial plants and animals. There will be loss of biodiversity on land and in the water.

The Pa Sak Jolasid Dam Project is an irrigation project in Thailand. Its water detention level is 960 million cubic meters, taking up a total area of 45,647 acres, covering parts of Lop Buri and Saraburi Provinces. The main impact will be people being relocated and not being reimbursed for their land.

In Russia, irrigation for farmlands has lowered the Volga River's flow, and limited its ability to regenerate. Water extraction has also reduced the water level of the Caspian Sea.

Conclusion
 
Following the construction of many dams there are many problems that degrade our water supply and many people's lifestyles. It may not be in your backyard but it may affect you in some way that you are just not noticing. For example, a proposed transmission line in northwestern Wisconsin would transport electricity transported by Manitoba Hydro. These situations are just a few out of hundreds of examples of destruction and contamination of landscapes and lifestyles from dams. Make yourself aware by accessing more information about some of these problems.
 
"Throughout the history of literature, the guy who poisons the well
has been the worst of all villains..."
-- Author unknown --

 

Sources

For more information:

Current Issues Affecting World Water Supply

Removing Dams in California

Dams and Development

River Revival

River Alliance of Wisconsin

Cracking Dams

Panda.org

International Rivers Network

Environmental Impacts of Dams

World Commision on Dams

BBC News

National Action Plan For Salinity