Posts Tagged ‘dam construction’

Oh, dam!

November 1, 2017

What Is A Dam? A dam is a structure, often quite large, built across a river to retain its flow of water in a reservoir for various purposes, most commonly hydropower.  In the U.S. there are over 90,000 dams over 6 feet tall, according to American Rivers.  In 2015 half of Earth’s major rivers contained around 57,000 large dams, according to International Rivers.  Dams are complicated. This blog presents a look at some of the benefits, consequences and impacts of dams, along with NWNL photographs of  North American and African dams in our case-study  watersheds.

BC: Waneta, Columbia River Basin, Waneta Dam on Pend d'Oreille RiverDanger sign at the Waneta Dam in the Columbia River Basin (2007)
Jones_111022_LA_2865Atchafalaya Old River Low Sill Control Structure, Louisiana (2011)

The slowing or diversion of river flows caused by dams – and related “control structures” – can have severe environmental impacts. Many species that reside in rivers rely on a steady flow for migration, spawning and healthy habitats. Altered river flows can disorient migrating fish and disrupt reproduction cycles needing natural seasonal flows.

US: Washington, Columbia River Basin, aerial views of Chief Joseph Dam
Jones_070622_WA_4119Aerial views of Chief Joseph Dam in the Columbia River Basin (2007)

The introduction of a dam into a river creates a reservoir by halting a river’s flow. This can severely impact the quality of water. Still water can cause water temperatures to increase. Resulting abnormal temperatures can negatively affect species; cause algae blooms; and decrease oxygen levels.

Jones_070628_OR_5171_MJuvenile fish bypass at the McNary Dam in the Columbia River Basin (2007)
Ethiopia: aerial of Omo River, construction site of Gibe Dam IIIAerial view of the construction site of Gibe III Dam in the Omo River (2007)

Bryan Jones, featured in Patagonia’s documentary “Dam Nation,” discussed today’s situation with four aging dams on the Lower Snake River (authorized in 1945) in his 2014 NWNL Interview:  “We used science then available to conquer and divide our river systems with dams. But today we can look at them and say, ‘Well-intentioned, but it didn’t really work out the way we would’ve liked it to.'”  Dams that may have been beneficial at one point in history must be constantly reassessed and taken down when necessary to restore river and riparian ecosystems and species. Some compare dams to humans, since they too have a limited life span of about 70-100 years.

Jones_100413_UG_9603Small dam across the White Nile River in Uganda (2010)
East AFrica: Uganda, JingaConstruction of the Bujagali Dam on the White Nile River in Uganda (2010)

There are well-intended reasons to build dams.  In the US, the Federal Emergency Management Agency (FEMA) has listed the values of dams on their website.  Those benefits  include recreation, flood control, water storage, electrical generation and debris control. These benefits are explained on the FEMA website.

USA: Alabama, Tennessee River Basin, Guntersville Dam (TVA)Danger sign at the Guntersville Dam, Tennessee River Basin (2013)
Jones_150817_CA_5888Parker Dam (a hydrodam) on the Colorado River, Southern California (2015)

Between 1998 and 2000, the World Commission on Dams (WCD) established the most comprehensive guidelines for dam building, reviewing 1,000 dams in 79 countries in two years. Their framework  for decision-making is based on recognizing rights of all interested parties and assessing risks.  Later, the European Union adopted this framework, stating that carbon credits from large dams can only be sold on the European market if the project complies with the WCD framework.

Many conflicts swirl around the impacts, longevity and usefulness of dams.  NWNL continues to study dam benefits versus their impacts, including removal of indigenous residents in order to establish reservoirs;  disruption of the downstream water rights and needs of people, species and ecosystems; and relative efficiencies of hydropower versus solar and wind.  Dam-building creates consequences.  Native Americans studied risks of their decisions for seven generations.  After the Fukushima tsunami caused the release of radioactive material, Japanese novelist Kazumi Saeki wrote:  “People have acquired a desire for technology that surpasses human comprehension.  Yet the bill that has come due for that desire is all too dear.”

Sources and resources for more information:

American Rivers, How Dams Damage Rivers

International Rivers, Environmental Impacts of Dams

International Rivers, Problems with Big Dams

International Rivers, The World Commission on Dams Framework – A Brief Introduction

FEMA, Benefits of Dams

National Hydropower Association, Why Hydro

NWNL, Interview with Bryan L. Jones

New York Times, Kazumi Saeki, In Japan, No Time Yet for Grief

All photos © Alison M. Jones.

Dam and Irrigation Projects Threaten Lake Turkana

January 11, 2013
Image

Omo River Delta as it enters northern Lake Turkana. © Alison M. Jones

Kenya’s Lake Turkana is the terminus of Ethiopia’s Omo River, which supplies 90% of the lake’s volume. L. Turkana (180 miles long and up to 30 miles wide) is the world’s largest permanent desert lake and largest alkaline lake. At 1,200 feet elevation, the lake is a closed (endorheic) basin, with high evaporation rates of 2.3–2.8 m/yr. Its high salinity ranges from 1.7–2.7%, due to no outlet, lower volume in the last 7,500 years, and recent volcanic activity.

The Omo River and L. Turkana are lifelines to indigenous Ethiopians and Kenyans. Ethiopia’s Gibe 3 hydro-dam, now in construction, will greatly decrease the Omo’s flow into L. Turkana. The Lower Omo Basin supports 200,000 indigenous agro-pastoralists. The Turkana Basin is home to 300 to 500 thousand people who depend on lake water for sustenance.

A new report documents how a dam and series of irrigation projects being built in Ethiopia threaten the world’s largest desert lake, and the hundreds of thousands of people who depend on it. It describes how hydrological changes from the Gibe III Dam and irrigation projects now under construction in the Omo River Basin could turn Lake Turkana in Kenya into East Africa’s Aral Sea (the infamous Central Asia lake that almost disappeared after the diversion of rivers that fed it). Download the full report.

International Rivers and Friends of Lake Turkana are calling for a halt to construction until there is a complete accounting of how the dam and irrigation projects will harm Lake Turkana, and a plan to ensure the lake does not suffer a hydrological collapse.
View photo gallery of Turkana people.

Image

Carrying water and reeds from L. Turkana. © Alison M. Jones

%d bloggers like this: