Posts Tagged ‘water hyacinth’

Aswan High Dam Leaves an Environmental Legacy

November 7, 2017

by Joannah Otis for No Water No Life

This is the second our blog series on “The Nile River in Egypt” by NWNL Researcher Joannah Otis, sophomore at Georgetown University. Following her blog “Finding Hapi-ness on the Nile,” this essay addresses perhaps the greatest elements of change created thus far by humans along the Nile. [NWNL has completed documentary expeditions to the White and Blue Nile Rivers, but due to current challenges for photojournalists visiting Egypt and Sudan, NWNL is using literary and online resources to investigate the availability, quality and usage of the Nile in those regions.]

Aswan_DamAswan Dam on the Nile River in Aswan, Egypt

Background on Aswan High Dam

The Nile River snakes south to north for 4,160 miles through ten North African countries until it reaches the Mediterranean Ocean.1 Its path is interrupted only by the great Aswan High Dam, which has brought both good and bad to the Egyptian people. Towering 364 feet tall and stretching 12,565 feet along its crest, the Aswan High Dam is impressive.2 This dam was opened in 1971 after a decade of construction and seeking funds from the Soviet Union.3 Its transboundary reservoir, Lake Nasser, which backs up into Sudan for 300 miles, holds nearly two years’ worth of water from the Nile River.

Benefits of the Aswan High Dam & Lake Nasser

The High Dam, replacing a 1902 Low Dam, annually generates more than 10 billion kilowatt hours of electricity, facilitating Egypt’s path to industrialization. This new dam also marked a major shift in Egypt’s agricultural prospects. Previously, Nile River Basin farmers were forced to depend on fickle seasonal flooding, which could bring appropriate levels of water one year and often completely washed away soil the next. Such unpredictability made it hard to grow a reliable crop; and the Nile’s single flooding season precluded farmers from having more than one harvest per year.

Lake Nasser’s surplus of water has well served the irrigation needs of Egypt and Sudan, since water availability is especially critical, given Egypt’s growing population and increasing water needs. (NB:  NWNL is studying these trends that portend dire water scarcity in the near future.) The Aswan Dam now allows for two to three crop cycles annually.  Nearby aquifers are inundated by increased amounts of water due to year long, rather than seasonal irrigation.  Water levels are carefully monitored and extra water is saved for times of drought. There has been huge economic benefit to the fact that the dams has allowed Egypt to triple the output of its most important and profitable crops, wheat and cotton.5  

Lake-nasserLake Nasser in Egypt.

Thus, the Aswan High Dam created a new future of irrigation water, flood control and electricity – but came with disconcerting drawbacks. Its story and continued influence on the Nile River illustrate how human ingenuity can inadvertently take a toll on the environments and ecosystems we so rely on.  The degradation of Nile ecosystems and the influx of increasing chemical runoff are reminders of the negative impacts that infrastructure, intended to improve quality of life, can have on nearby environments and habitats for all species, including humans.

Consequences of the Aswan High Dam & Lake Nasser

While Lake Nasser reservoir has allowed for controlled downstream flows into northern Egypt, that backlog of Nile water forced the relocation about 100,000 people to other lands in Sudan and Egypt.6 Abu Simbel Temple and 22 historical structures fortunately were moved under UNESCO’s watchful eye, yet Buhen Fort, the Fadrus Cemetery and other archeological sites (whose relocation would have been too costly) were submerged.

Stagnant waters in Lake Nasser have threatened the health of people using or residing near the Nile River waters. Downstream, the dam promotes the presence of schistosomiasis, a parasitic disease also known as bilharzia or “snail fever.” Schistosomiasis kills more than 200,000 Africans annually; and 20 million sufferers develop disfiguring disabilities from complications, kidney and liver diseases, and bladder cancer.

Egyptian_harvest.jpgTomb Painting of Peasants Harvesting Papyrus

Seasonal flooding once brought thick layers of dark silt to farms, which farmers used a natural fertilizer. Unfortunately, the Aswan High Dam almost completely blocks the movement of nutrient-rich sediment downstream. (NB:  NWNL has seen similar impacts of Ethiopia’s new Gibe Dams, ending 6,000 years of flood-recession agriculture practiced by pastoralists in the Lower Omo River Basin.) As rich Upper Nile sediments collected behind the dam, Egyptian farmers resorted to toxic chemical fertilizers that drain into the Nile. These pollutants can cause liver disease and renal failure in humans.7 

Farming phosphates running into the river increase algae growth. Algae blooms, elicited by excess nutrients (eutrophication), produce cyanotoxins, which affect the health of fish and may poison humans.At the same time, fish populations no longer benefit from nutrients that used to be in upstream Nile sediments. Aquatic species in the Mediterranean Sea near the Nile Delta have suffered similarly from decreased natural nutrients and increased chemicals.9

Riverbanks also suffer from a lack of replenishing sediments as their erosion continues unchecked.  Prior to the dam’s construction, the average suspended silt load was 3,000 parts per million (ppm). Post-construction silt levels have declined to 50 ppm.10 Further downstream, the Nile Delta suffers from a lack of silt replenishment. [NB:  NWNL has documented parallel deltaic losses and damage in the U. S., as  levees along the Mississippi River withhold sediment that used to rebuild storm erosion in the Mississippi Delta.]

Silt-free water along with a lower current velocity and steady water levels have enabled invasive aquatic weeds to infest the Nile River and its irrigation canals. Large volumes of aquatic weeds, water hyacinths in particular, create stagnant water conditions, impair water flow, provide breeding grounds for malaria-carrying mosquitoes and prevent the passage of boats whose propellers become clogged with invasive weeds.  Prior to the dam’s construction, these weeds were unable to flourish due to the Nile’s varying water levels and the force of its flow.11

Eichhornia_crassipes_C.jpgWater Hyacinth  (Credit: Wouter Hagens)

Erosion in the Nile Delta is especially threatening because it has led to saltwater intrusion.   (NB: Again, this is another issue also occurring in the Mississippi River Delta.)  Increased groundwater salinity from the encroaching Mediterranean Sea is decreasing cotton and rice yields.12 Additionally, fertilizers have further heightened saline levels.13

Beyond Aswan:  Footnote by NWNL Director Alison Jones

In 2009, Egypt was the most populous, agricultural and industrial country in the Nile Basin.14 The Aswan Dam has been a major factor in this march by Egypt to progress and prosperity.  However, just as the Aswan Dam came with a price – so will the upstream Grand Renaissance Dam, now under construction in Ethiopia on the Blue Nile River.  It is likely the impacts of this new Ethiopian dam – the largest ever on the African continent – will be even more consequential to Egypt than those of the Aswan High Dam.  It seems a new chapter is about to be written regarding settlement of transboundary conflicts spawned from disputes over dam impacts and upstream-downstream water rights.

Sources

1“Nile River Facts.” Africa Facts. Web. 2017
2Caputo, Robert. “Journey up the Nile.” National Geographic. May 1985. p 602
3Caputo, Robert. “Journey up the Nile.” National Geographic. May 1985. p 602
4Caputo, Robert. “Journey up the Nile.” National Geographic. May 1985. p 600
5Biswas, Asit K.; Tortajada, Cecilia. “Impacts of the High Aswan Dam.” Third World Centre for Water Management. 2012. p 389
6Caputo, Robert. “Journey up the Nile.” National Geographic. May 1985. p 602
7Theroux, Peter. “The Imperiled.” National Geographic Magazine. January 1997.
8El-Sheekh M. “River Nile Pollutants and Their Effect on Life Forms and Water Quality,” in “The Nile.” (Dumont H.J, Monographiae Biologicae, Vol 89. Springer, Dordrecht)
9Biswas, Asit K.; Tortajada, Cecilia. “Impacts of the High Aswan Dam.” Third World Centre for Water Management. P 389. 2012.
10Biswas, Asit K.; Tortajada, Cecilia. “Impacts of the High Aswan Dam.” Third World Centre for Water Management. P 385. 2012.
11El-Shinnawy, Ibrahim A.; Abdel-Meguid, Mohamed; Nour Eldin, Mohamed M.; Bakry, Mohamed F. “Impact of Aswan High Dam on the Aquatic Weed Ecosystem.” Cairo University. September 2000. p 535-538.
12Theroux, Peter. “The Imperiled.” National Geographic Magazine. January 1997.
13World Wildlife Foundation. “Nile Delta flooded savanna.” Web. 2017.
14El-Sheekh M. “River Nile Pollutants and Their Effect on Life Forms and Water Quality,” in “The Nile.” (Dumont H.J, Monographiae Biologicae, Vol 89. Springer, Dordrecht)
All photos used based on fair use of Creative Commons and Public Domain.

Even invasive species can be beautiful

December 19, 2014
Water hyacinth (Eichhornia crassipes) is one of the world’s worst aquatic weeds. It is characterized by rapid growth rate, extensive reproductive output and broad environmental resistance. It creates dense mats of vegetation that restrict oxygen in water, causing deterioration in water quality, fish mortality and declining biodiversity. A healthy acre of the plant can weigh 200 tons! These floating masses block waterways and harbors, costing millions of dollars of damage every year.
Water hyacinth grows in lakes, estuaries, wetlands, rivers, dams, and irrigation channels on every continent except Antarctica.

Screen Shot 2014-12-19 at 1.45.53 PM– Posted by Jasmine Graf, NWNL Associate Director

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