Sunday, October 23, 2016

Flood Management - Hard Engineering

 
Three Gorges Dam



The Three Gorges dam was constructed at Yichang on the River Yangtse. The capacity of the reservoir should reduce the risk of flooding downstream from a 1-in-10-year event to a 1-in-100-year event. Not only will this benefit over 15 million people living in high-risk flood areas, it will als protect over 25,000ha of farmland. The dam is already having a positive impact on flood control, navigation and power generation, but it has caused problems. The Yangtse used to carry over 500 million tonnes of silt every year. Up to 50% of this is now deposited behind the dam, which could quickly reduce the storage capacity of the reservoir. The water in the reservoir is becoming heavily polluted from shipping and waste discharged from cities. For example, Chongquig pumps in over 1 billion tonnes of untreated sewage per year. Toxic substances from factories, mines and waste tips submerged by the reservoir are also being released into the reservoir. 

Most controversially, at least 1.4 million people were forcibly moved from their homes to accommodate the dam, reservoir and power stations. These displaced people were promised compensation for their losses, plus new homes and jobs. Many have not yet received this, and newspaper articles in China have admitted that so far over $30 million of the funds set aside for has been taken by corrupt local officials.

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