Hydroelectric Dams

The Hoover Dam. Source: selbst fotografiert, 2003

Following on from my recent post on the Three Gorges Dam, I'd like to look at the productive possibilities that these hydroelectric wonders are capable of. Dams have long been used as a protective barrier against river flow and due to them being predictable and reliable the use of dams has developed in to an efficient way to produce and retain electricity. 

The Hoover Dam is a great example of the prowess and incredible constructive capabilities of America around the time of the Great Depression. The aim of Davis the constructor was to build a high dam and deep canyon upstream to tame the out of control river. The dam spans Construction of the Dam was begun in March 1931 and shared between 6 major construction firms. It took two years to divert the river flow and bore out enough rock before work on the structure could start. 

          "no more floods, no more droughts"

This was Davis' aim. This has certainly been achieved and the Dam is classed as a modern civil engineering wonder and is recognised as one of the seven wonders of American construction.

Benefits of dams

• Can be used to control the river flow; increasing irrigation of land whilst also preventing droughts and floods. 
• Electricity can be generated reliably, predictably and efficiently.
• If constructed well a dam is safe and long lasting.

Drawbacks of dam construction

• The construction of a dam is dangerous, although not so much nowadays as a century ago (96 people died building the hoover dam).
• The cost is great.
• The river flow is altered and the creation of a reservoir can lead to the displacement of thousands of people (as seen with the Three Gorges Dam where over a million people were displaced).
• Loss of land also needs to be taken in to consideration with the reservoir construction. 

Whilst researching I came across this recent Guardian article about the dangers of large dams in China on both national and global stability. The article focuses on China's five year plan from 2011 to 2015 that includes building 60 dams and 12 along their last free-flowing river. This is predict to harm ecosystems, displace people and cause catastrophic seismic events; due to the increased pressure of the water on an already earthquake prone area. The link to the article is below:

http://www.guardian.co.uk/environment/2013/jan/29/hydro-dams-china-ecosystem