The Three Gorges Dam, Geography Coursework?

Question

I'm doing my Geography Coursework and I'm stuck on this section. . .

How will the building of the Dam affect the drainage basin hydrological cycle and river processes?

Really appreciate it, if you could help :)

Thank you! x

Answer 1

http://www.cnn.com/SPECIALS/1999/china.5...

http://www.geographypages.co.uk/3gorges....

Answer 2

Here are some advantages and disadvantages of the Three Gorges Dam.

Supporters say the benefits of the project far outweigh the

costs.  The principal advantage of the project is to generate power

to keep pace with China's economic growth.  It is estimated that

China's power output must rise by 8 percent annually to keep pace

with 6 percent annual increase in gross national product.  In

practical term, that means the nation's total 1990 power capacity

of 130 million kilowatts must grow to 580 million by the year 2015.

Advantages

1.   Flood Control.  Chinese officials note that the dam will relieve the danger of flooding.

2.   Emissions reduction.  Another advantage of the dam is to reduce emissions of sulfur dioxide and carbon dioxide.

3.  China is enforcing tight rules aimed at preventing construction work from causing environmental pollution, while advanced facilities are being installed to treat construction waste. By the year 2000, over 90 percent of waste water from construction is expected to be treated.



Disadvantages

1.  Relocation.  Chinese officials estimate that the reservoir will partially or completely inundate 2 cities, 11 counties, 140 towns, 326 townships,and 1351 villages.  About 23800 hectares, more than 1.1 million people will have to be resettled.

2.  It will threaten the river's wildlife.  The dam will alter the natural environment, and therefore, an almost infinite number of species will be affected by the project.

3. The Three Gorges project will submerge some of China's most famous historical scenery and tourist sites.

4.  The weight of millions of tons of water behind a dam can increase the chances of an earthquake.

5.   The dam will disrupt heavy silt flows in the river. It could cause rapid silt build-up in the reservoir, creating an imbalance upstream, and depriving agricultural land and fish downstream of essential nutrients.  

Answer 3

I can't infer from the texts I have here with me, but I hope it helps:

Environmental issues with the Three Gorges Dam, which is currently under construction on Yangtze River, include degraded water quality, detriments to wildlife, potential riverbank collapses, and potential silt related falling of coastal areas.

Currently, the quality of water in the higher banks of Yangtze is slowly worsening, due to the dam's preventing dispersal of pollutants; algal blooms have risen progressively since the dam’s construction; and soil erosion has increased, causing riverbank collapses and landslides. The report detailing this was officially released in September 2007. Senior Chinese government officials and scholars said the dam could cause a "huge disaster ... if steps are not taken promptly." The same scholars and officials previously had defended the Three Gorges Dam project. However, the Chinese embassy in the United States has firmly promoted it. Xinhua News Agency also reported that tens of billions of yuan had been spent to prevent pollution and geological disasters by tree planting, measures to maintain biodiversity, shutting 1500 polluting industrial and mining enterprises and building 70 sewage and waste treatment plants, all of which are "progressing well."



Three Gorges Dam Of the 3,000 to 4,000 remaining critically endangered Siberian Crane, a large number currently spend the winter in wetlands that will be destroyed by the Three Gorges Dam. The dam contributed to the functional extinction of the Baiji Yangtze river dolphin. Though it was close to this level even at the start of construction, the dam further decreased its habitat and increased ship travel, which are among the factors causing what will be its ultimate demise. In addition, populations of the Yangtze sturgeon are guaranteed to be "negatively affected" by the dam.

While logging in the area was required for construction which adds to erosion, stopping the periodic and uncontrolled flooding of the river will lessen bank erosion in the long run. The build up of silt in the reservoir will, however, reduce the amount of silt transported by the Yangtze River to the Yangtze Delta and could reduce the effectiveness of the dam for electricity generation and, perhaps more importantly, the lack of silt deposited in the peninsula could result in erosion and sinking of coastal areas.

There are two hazards uniquely identified with the dam.[ citation needed ] One is that sedimentation projections are not agreed upon, and the other is that the dam sits on a seismic fault.[61]

The Three Gorges area currently has 10% forestation, down from 20% in the 1950s. At current levels 80% of the land in the area is experiencing erosion causing about 40 million tons of sediment to slide into the Yangtze annually.[57] The relocation of people from the reservoir area will cause further deforestation and erosion due to agricultural needs.

Excessive sedimentation can block the sluice gates which can cause dam failure under some conditions. This was a contributing cause of the Banqiao Dam failure in 1975 that precipitated the failure of 61 other dams and resulted in over 20,000 deaths. Critics believe that the Yangtze will add 530 million tons of silt into the reservoir on average per year; in time, this silt could accumulate behind the walls of the dam, clogging the turbines' entranceway. However, because China has began constructing four other megadams (see below) on the upstream of Yangtze since 2006, the sedimentation from upstream would be much less than originally predicted. But the absence of silt down stream would still have two dramatic effects:

Some hydrologists think that this could make downstream riverbanks more vulnerable to flooding. The city of Shanghai, more than one thousand miles (1600 km) away from the dam, rests on a massive plain of sediment. The "arriving silt -- so long as it does arrive -- strengthens the bed on which Shanghai is built... the less the tonnage of arriving sediment the more vulnerable is this biggest of Chinese cities to inundation..."

The Benthic sediment build up is a cause of biological damage and reduction in aquatic biodiversity.