Flood-Control Dams, Essay Example

Civilizations have been impounding water as a method of containing water for flood control and   irrigation for millenia (Joyce, 2009). The history of irrigation goes back to the ancient Sumerians who practiced irrigation in what is now modern day Iraq in 5000 B.C. In the first century B.C., low dams had been successfully build in the Mediterranean, the Middle East, Central America and China (Joyce, 2009). The first mega dam, the Hoover Dam in the Colorado River’s Black Canyon was built in 1936 (Joyce, 2009). Dams have been touted as a    solution to power shortages and also flood control. However, today their effectiveness is being questioned.

Historically, it has been shown that damming rivers is ineffective in controlling flooding. For example, China has been adding barriers to the Yellow River and its tributaries for thousands of years. However, it has not stopped the river from flooding surrounding villages over 1,500 times in the past 3,000 years or changing its course on at least 26 different occasions, 9 of those times very violently (Goldsmith, and Hildyard, 1984). Since 1937, the U.S. has spent $12 billion on structural controls and further massive sums on flood relief. Yet since then, the average annual cost of flood damage has risen from $350 million to between $3.5 billion and $4 billion in 1976 (Goldsmith, and Hildyard, 1984).”

There are environmental problems that are caused by dams. Dams disrupt the natural flow of the river. The Colorado River, for example, used to be “a silty, warm flow of water that ran 2,300 kilometers, ending in a rich delta in Mexico. Today, northern Mexico gets only a meager allotment of water that has been recycled for irrigation as many as 18 times and the delta is dry except in years of exceptional rain (Joyce, 2009).”  Another issue with dams is that they cause siltation, or the deposit of silt that would normally flow down stream to be deposited. Siltation can “reduce dam capacity, thereby diminishing generating power, or deplete downstream farmlands, which are dependent on silt for nutrients (Joyce, 2009).”

Goldsmith and Hildyard (1984) argue that dams and made made flood control actually make flooding worse instead.  They argue that building up concrete embankments by nature increases the flow rate of the river, funneling the damaging flood waters downstream in a more destructive way and that severe flood damage. This is just what happened with hurricane Agnes hit the drainage basins of the Upper Ohio River. The flooding, which caused $3 billion in damages, occurred where elaborate structural controls had been put up (Goldsmith, and Hildyard, 1984). Incidents like this, and many others, should be a sign that perhaps it is time to re-evaluate the effectiveness of using dams as flood-control.

References

Goldsmith, Edward and Hildyard, Nicholas (1984) “The Myth of Flood Control” Web. Retrieved 28 October, 2010 from             http://www.edwardgoldsmith.org/page157.html

International Commission of Irrigation and Drainage (1999) “Role of Dams for Irrigation, Drainage and Flood Control” Web. Retrieved 28 October 2010 from http://www.icid.org/dam_pdf.pdf

Joyce, Stephanie (2009) “Dams – Advantages and Disadvantages” Environment, Health and Safety Online Web. Retrieved 28 October, 2010 from http://www.ehso.com/ehshome/energydams.htm