While we all enjoy our recreational areas, especially those with a large body of water that allows us to take our toys out and enjoy a nice summer day on the water, we often forget the true purpose of those body of water that are man made. These waters are a means of protecting people from a drought, and having a ready supply of drinking water. In terms of conservation, they provide homes for a myriad of wild life. Here I will list the top 5 dam disasters in the world, now they may be anything from the dams breaking to the major ecological effects the dam had on the surrounding area.
1. South Fork Dam (The Johnstown, PA Flood)
The South Fork Dam held back the Lake Conemaugh, and was owned by South Fork Fishing and Hunting Club, with Andrew Carnegie and Henry Clay Frick as some of its members. The members of the club filled the lake with exotic fish so that they could get in their boats and of course fish them out. While they enjoyed their exotic fish they soon found that the fish had been escaping the lake through the spill way, and fishermen down river had been catching them. So the South Fork Fishing and Hunting Club came up with a simple way to prevent this, they would place a screen across the spillway to prevent fish from escaping.
This was a very effective plan, and worked in keeping their fish from escaping the lake. However, it had another effect on the dam itself, during storms the spillway acts as overflow preventing the dam waters from over topping the earthen dam. The dam was also kept at a water depth that was near its' maximum. These factors all came together during a storm on May 31, 1889. The spillway became clogged with detritus from the storm including branches, logs, leafs, and more. The water soon rose to the top of the dam, and over topped it. Once a dam has water overflowing it is only a short time before it washes out.
The torrent of water, close to 20 million tons, flooded out into nearby towns causing devastation and death. Altogether 2209 people died by this flood. The wall of water washed away 1600 homes, and caused $17 million in property damage. The flood was further exacerbated by a stone bridge in Johnstown where debris collected, 30 acres worth, caused the flood wave to bounce back on itself causing even more damage.
Through the simple act of trying to preserve the money spent on fish a club helped cause one of the worst flood disasters in American history. For further information on the Johnstown Flood and the South Fork Dam visit The Johnstown Area Heritage Association.
2. The Aswan Dam, Egypt
The Aswan Dam was built in 1960 and was completed in 1970. It was constructed as a means to control flood waters on the Nile River. This dam has not overflowed in anyway, it's disaster is in the construction and environmental effects. The dam losses approximately 11% of its' water to evaporation, has caused disease, and hold silts and sands from those down river. Beneficially it does produce electricity for the Egyptian people, controls the flooding, and allowed multiple crops to be grown each year.
The silts and sands of the Nile replenish the farming soils each year during the flood ensuring that the farming grounds of the Egyptians have plenty of nutrients for their crops. The silts now sit behind the dam unable to make their way downriver. This has caused some major erosion problems, loss of the Nile delta, and has made the dam actually shrink since the silts must be dredged out to keep it from overflowing. Some diseases have become an epidemic in the region, including snail fever or Schistosomiasis. These snails would have been carried away during the flooding helping to prevent an over population of them. Since the dam was built there has been increased cases of snail fever in Egypt, which can be very excruciating for the person infected by the parasites.
Salt water intrusion, which is salt water moving into fresh water areas, has also become a problem with the decreased flow of the Nile River. While at full flow the river would enter the delta and constantly keep the salt water at bay, but since the water has been dammed it no long does this. Increase salinity has been seen within the river.
Though the environmental impact has not been good there are some beneficial effects to the dam. Increased tourism has helped bring money to the Egyptian economy. The dam has also created jobs in pesticide, and fertilizers areas, of course with these there is also some serious pollutant and environmental side effects. While looking at this dam it would be up to the reader if this dam is a disaster or a benefit, a environmental blunder or economic boon so to say.
3. Three Gorges Dam, Yangtze River, China
The largest dam in the world, was held by China in the highest regard as a symbol of the communist party. This dam construction started in the 1990's and is still not full completed. Costing around $25 billion dollars the Dam has astronomical effects on the environment in China. China however chose to ignore these effects and continued to build this monster dam. China suppressed much of the arguments against this project using it as a stepping stone into world economics.
Though recently, around 2007, China has started admitting it folly in building this dam without first thinking of all the environmental factors behind it. Let us start with the landslides. Saturation of water into the land around the 600km lake that began filling in 2006. Shorelines have caved in, subsidence, causing huge wave which have come ashore killing farmers and livestock. Slides have also taken place in 91 other places along the shore as of 2007. Landslides in large lakes can be devastating to surrounding areas, and cause mini tsunamis in those lake that come ashore just as they would in a ocean.
Once again sedimentation is occurring behind the dam from the silts that would normally move down the river are stopped by the dam and collect behind it. This can cause major problems for the shipping lanes the run through the Yangtze River. If the river behind the dam becomes so silted up ship will no longer be able to pass through the area further causing economic strife in China.
The wildlife in the area is severely effected by the dam as natural river shoals are diminished from the lack of slits downriver from the dam. Pollution has been killing wildlife as more and more industrial plants open in the area without proper regulations to keep them in check. Although the Chinese government is trying to clean the area up, it has closed 1500 factories and built more than 70 water treatment plants. They have also spent billions of dollars to geologically stabilize the area.
In conclusion, there has been many disasters associated with dams, and these are just a few. Some have major environmental impacts that were not anticipated by the people building them while others were directly related to mans need to have areas of recreation. Dams are an essential part of and industrial or post-industrial society, they provide power, a ready supply of water, and in some case fun. The impacts these dams have need to be closely watched and regulated to ensure that no disasters happen. We can easily look at past events to ensure that the same mistakes are not made, and ensure that future dam projects find a balance between nature and man.