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Civil Engineers create the infrastructure which sustains civilised life, yet the public often perceives construction projects as affecting the natural environment
Civil Engineers create and build infrastructure that is necessary in order for civilised life to occur as we know it at present day. If we take a normal Londoner as an example, majority of his actions throughout the day will have reliance on some form of civil engineering infrastructure. This can be seen from a first thing that a person does in the morning, which is the use of a toilet. Water running from a tap and ability to flush the toilet are all possible thanks to infrastructure that is created by Civil Engineers. Adequate sewerage systems allow for dirty water to be distributed away from such places as households, and allowing for water to be treated making sure that other water sources such as rivers are not polluted by the dirty water. Sewerage systems have contributed a great deal to sanitary issues preventing water borne diseases such as cholera, typhoid and many others. It is disappointing to say however, despite knowledge how to solve and deal with dirty water that around four children die every minute in developing countries because of diseases developing from inadequate sanitation and unsafe water . This problem is mainly due to lack of finance to create infrastructure that can deal with sanitation issues. Cities such as London and people that live in them often take these things for granted. In developed countries such as United Kingdom, water supply is treated as a basic human right and funding is allowed wherever the demand for it occurs. As population is constantly increasing, ever growing demand for water supply also increases as people become lavish with use of water for indoor toilets, baths, washing machines, washing their cars, garden hoses and many other purposes.
Apart from infrastructure that deals with supply and disposal of water, there are many other examples where Civil Engineers have contributed to sustaining civilised life. This can be portrayed by mentioning the building of roads, rail links, bridges, canals, tunnels, airports and docks, all which help commuting for people easier, either it being from home to work or leisure to other countries. However, it does not just stop here, diversity of projects is enormous which sustain life as we know it, and for purpose of this paper alongside other infrastructure already mentioned, energy is the one issue that particularly has to be pointed out. Taking only electricity as an example, amount of places it can come from, is also very diverse. Coal power and nuclear stations are just an example along with many renewable sources such as hydro (i.e. dams), wind and solar. Civil Engineers would most definitely be involved in building any of these facilities that can generate electricity. It would be impossible to think of a present life as we know it today without electricity. Everything that we do, either it being at home, work or outside our home (i.e. commuting by train) will involve use of electricity.
Therefore, if our every day activities comprise and rely on use of infrastructure that helps maintain civilised life as we know it at present, why do people object when there is a proposal to build something that will help us go about our every day activities. Could a typical Londoner imagine his life without electricity and water to flush his toilet or water to drink and shower? If building a dam can help address these issues and bring with it many other benefits why would he or anyone else as a matter of fact object to it and perceive it as a bad idea? Answer to this question is not easy because there are many aspects that have to been taken into an account arising particularly from political and sustainability issues as well as economical and social reasons. The remaining content of this paper will be to evaluate negative issues with building a large scale project such as a dam, and also evaluate why society should consider and allow building of such a project.
Benefits of Dams
Firstly, let us concentrate and evaluate some of the benefits that dams can bring and have brought to societies. They can provide them with water to drink and use, protect from flooding (both river and marine flooding), create recreational area, irrigate water necessary to grow food and in some cases enhance the environment.
Dams have been constructed for many thousands of years, and during different times, needs of societies has changed and so has the dam construction. In the past basic concept would have been to build some form of a barrier across the river. Because of lack of knowledge and materials, majority of the past dams would have been some sort of an embankment dam. Typically they would have been on small scale and constructed of excavated natural materials (Earth dams). In United Kingdom small reservoirs constructed from such dams were by medieval monasteries to provide supplies of fish, generally carp . Back then fresh food could have been a main reason, hence the nutritional benefit from entrapped fish.
As time went on discovery of concrete and better understanding of engineering principles allowed for bigger dams. Most of dams today are multipurpose for reasons mentioned earlier. Arch dams are concrete or masonry dams, which are curved upstream to transmit the major part of the water load to the abutments. Their shape has the benefit that it can hold back large amount of water. Hydropower dam uses the difference in water level between the reservoir pool elevation and the tailwater elevation to turn a turbine to generate electricity . These are just two of many other more modern dam design concepts.
Coming back to benefits that dams bring, we need to look at back particularly around time of industrial revolution in late 18th century, to see how much death rate has fallen by introducing domestic water supply. Provision of clean water supply and disposal of sewage brought down many deaths related to dirty water. In Britain in 1832 there were 30,000 deaths from cholera and in 1849 60,000 . This just comes to show how bad the problem was at that time because of lack of sanitation, as overcrowding occurred since people were coming into cities for jobs. Larger towns such as Manchester, Liverpool and London than started constructing upstream reservoirs to supply ever increasing population with clean water. The benefit of this can be seen by looking at Enteric deaths (high fever illness) in Figure 1 , in England and Wales.
It can be seen that introduction of clean water supply, death rate fell sharply right across the country and that by 1940's it was virtually at zero.
One of the other benefits that dams provide is the flood protection from river flooding. This can be achieved in two ways. One of them is by direct protection while second is by routing the flood through a reservoir provided for other means, hence reducing the peak flow in the river downstream of it . At present EA (Environmental Agency) in United Kingdom is particularly pointing out that it does not want new development to increase flooding downstream. By constructing a dam and having and empty reservoir, allows for storage of water to be provided at crucial times when there is high precipitation, and the storage reservoir acts as a flood defence. Constructing a dam without having increased flooding downstream can be possible therefore fulfilling Environmental Agency's request.
Good example where construction of a dam has brought flood protection to a very large population is The Three Gorges Dam in China. The Yangtze River on which the dam is constructed has claimed 300,000 lives of people that have drowned due to floods in the last century. It has also displaced millions of people. At the moment, dam provides flood protection to fifteen million people that live in the flood plain .
Land reclaimed from sea can be used for either agricultural purposes or for land development. This can only be achieved by keeping sea water out and only way to this is by constructing dams, called sea defences.
Water from reservoirs can be used for irrigation. This is when water from the reservoirs is supplied to land where crops and plants are, enabling them to grow. This is particularly important in countries with hotter climate and which suffer great deal from dry seasons, hence relying throughout the entire season on irrigation water. In 1877, low Nile flood failed to irrigate adequately, causing famine and death among the six and half million Egyptian population .
Reservoirs created from dams can offer Sites of Special Scientific Interest. Creating manmade (artificial islands) which allows for birds to rest free from predators such as foxes, and lagoons can be found along the offshore to maintain shallow wetlands for wildlife even during drawdown. Woodland plantations along the shore can prosper thanks to supply of water offering spectacular and very beautiful habitats that can support very large number of wildlife that can find it difficult to survive in wider countryside.
Commercial benefits arise from recreational opportunities that can be created. Since reservoirs allow for fish to thrive, fishing on such lakes is a huge potential and source of tourism. Not only this but since most reservoirs are quite big, they offer a safe environment to sailing clubs, also boating and even swimming. Such activities as bird watching, bicycle riding, nature walks, camping and others can be possible around the reservoir, all which can enhance tourism.
One of the main benefits associated, for purpose of this paper is the hydro power induced from building dams. Since turbines that generate electricity are fuelled by water, it is a clean fuel source offering no emissions. Because it relies on water cycle, which in turn relies on series of events in nature one of them being the sun, it is considered as a renewable power source. The reservoir behind the dam can be used to turn the turbines especially when the demand for electricity jumps .
Taking United States as an example, 80% of the renewable energy is accounted by hydroelectricity. This is because no emissions are released by burning of fuels which is the problem with nuclear and coal fired power stations. Just to demonstrate how much carbon dioxide released into the atmosphere is saved by use of hydropower, National Hydropower Association (in USA), estimates it to be at 77 million metric tons. This amount would be equivalent to emissions released from driving sixty two million cars for one year . Production of electricity from hydro power is non polluting for other reasons too. Since no chemicals are involved with production, none have to be disposed of which is another great benefit to the environment. In addition, noise pollution is not of a major concern since many dams are located in isolated areas.
Negative aspects of Dams
Despite benefits that dams have brought, they have also caused major environmental impacts. Even though they are regarded as non polluting source of electrical power and very important in water supply systems, better understanding over the years of environmental impacts it causes makes many people want to oppose their construction. Not only does the environment suffer from constructing dams, there are also major economic, social and political issues or concerns.
Perhaps the best way forward to describe negative side of building a dam would be to focus on one of the most controversial dams ever built. This is undoubtedly The Three Gorged Dam in China. From the very first stage, at proposal, it raised all of the concerns already mentioned. It has to be noted however, benefits are always much easier to identify and quantify, where as costs on the other hand manifest themselves over many years and in variety of ways.
Three Gorges Project
Before we proceed onto describing disadvantages of the Three Gorges, we need to understand more about the actual project. The dam stretches 2.3 kilometres across the great river Yangtze. The height of the concrete wall reaches almost 200 metres, has a volume of 40 million cubic metres, and has created a reservoir 600-kilometres long with a total storage capacity approaching 40 billion cubic metres . The reservoir is about twice the size of the Isle of Weight. So far twenty one generators have been installed, generating around 62 billion kWhr of electricity and this is only two thirds of the maximum level that is being aimed at achieving . Under original plans, the power generated from The Three Gorges was meant to satisfy some 10 percent of total electricity consumed in China. This target hasn't actually been realised because demand for electricity in China has gone up at a higher rate than it was estimated for during design stage. This figure would seem to be at about 4 percent satisfying current demand.
Economic aspect in terms of cost is hard to quantify. Latest estimates of the total construction say that total cost has been around $30 billion. Funding has come from four internal sources in China and a number of international financiers. This is a very large amount of money that has been plugged into the project and its estimated that after 2010 when all the proposed 26 turbines are installed and power production is at full capacity, it will take ten years to repay the loans . However, actual cost are hard to compute because of after treatment works and threats such as landslides and earthquakes, political corruption and massive relocation and ecological losses, all which might require substantial amount of money for remedial action.
Ecological problems include impacts on the fisheries of the Yangtze River basin and sedimentation issues. The basin contains thirty six percent of all freshwater fish species in China. Twenty seven percent of all of China's endangered freshwater fish are in the Yangtze basin . Fish population are subject to fluctuations because of the disruption that the project has on chemical and temperature composition of the water. Dam blocks migration of fish and access to spawning grounds, and also blocks food resources available to those fish. The major dynamics of how river works are altered by the dam and as a consequence fish are not being able to adapt to change in environment.
From WWF's Living Planet Report, from 1970 to 2000, freshwater fish species have declined drastically. Fifty four percent of 195 indicator species have exhibited a population decline, which can be seen in Figure 2 .
Dams are called up as one of the most influential in this decline because they impact fish migration and downstream wetlands. Data released from Three Gorges Dam corresponds to issue as after construction annual harvest of carp was somewhat fifty percent below pre-dam statistic .
River sedimentation and sediment flow is another problem. Traditionally Yangtze river has transported large amount of sediment from its upper reaches all the way to China's sea. Completion of the dam calls cause of concern for operational issues as well as environmental. Sediment has decreased at Yangtze delta by thirty three percent of what it was before dam construction. Decrease in sedimentation flow to the delta, allows for problem of coastal erosion. How big the problem is can not be determined at present but will be problematic most certainly in decades to come .
China has about 83,000 reservoirs that are built for various purposes, and 330 of these are major in size. Sediment deposition in 230 of them have become a significant problem, resulting in a combined loss of 14 percent of the total storage capacity. Some have even lost up to 50 percent of potential storage capacity . Increased sedimentation levels can greatly influence hydroelectric power output and flooding prevention.
Seismicity and Geological Instability
Filling up of large reservoirs can cause seismic activity and also due to pressure it builds up on local faults. Such an action was predicted for Three gorges Dam alongside increased landslides which are related to seismic activity. Major landslide occurred shortly after the reservoir was filled near town of Qianjiangping on the the Qianggan River near its confluence with Yangtze mainstream. Twenty four million cubic metres of rock and earth slid into the Qinggan river, killing, destroying property and blocking path for boats. In 2007 officials and experts have admitted that Three gorges reservoir has caused more frequent landslides. Mayor of Chongqing, said that the shore of the reservoir had collapsed in ninety one places and total of thirty six kilometres of shoreline caved in. as danger zone extends new resettlement of the people have to be made which not only affects the societies but the cost to the government of relocation.
Pollution of water in Three Gorges reservoir also has to be accounted for when looking at negatives of constructing a dam. According to the Chinese Academy of Sciences, Yangtze river has become the biggest sewer system in China. Around Three Gorges reservoir area, there are around three thousand industrial and mining enterprises which release more than one billion tons of wastewater annually, containing more than fifty different pollutants. Included in the waste water are such poison elements as mercury, cadmium, chromium, lead and cyanide. Industrial sources account for the majority of the pollution, but large amounts also come from agricultural run off, residential wastewater, urban sewers and pollution from ships. Studies that are curried out for pollution do not even consider township-level enterprises. There is very little treatment of industrial wastewater flowing into the reservoir area, and no treatment of residential wastewater. Everyone so far has been relying on the rivers capacity to flush pollutants out to sea to keep it clean. Following construction of the Three Gorges dam, the rivers flow is greatly reduced and with it the flushing capacity of the river . What is also alarming is that there are a number of unknown diseases that have afflicted local workers on the river, possibly from the increased pollution within the river. Worrying also is the issue of these harmful pollutants spreading further into the surrounding environment especially into other water sources, since settling of pollutants in the reservoir has potential for underground water movement.
The biggest cost of the construction of Three Gorges dam is the resettlement not only in terms of financial cost but in loss to societies and cultures as well, since 1.6 million people had to be abandon their homes or otherwise be flooded. The problem is that one third of those people that had to be moved are farmers, and finding new land for them that can be used for farming is difficult. Chinese government has tried to persuade farmers to give up farming and move into urban housing and take up employment in cities . Over 100 towns have been flooded completely and some 100 archaeological sites have been lost to the reservoir. Some of the cities have had a cultural history going back to well over one thousand years. With new problems not accounted for such as increasing danger zones from landslides new estimate suggest that further four million people are to be effected with resettlement .
It is not just the loss of home that is an issue, tensions and conflicts regularly occur with local population and new migrants that have arrived. Inadequate planning has left people with bad farming land, food insecurity, joblessness and social status.
Although the world is becoming a more peaceful place, the threat of an attack on the Three Gorges dam cannot be dismissed. If it were destroyed by military attack, the consequence for military, and for the entire nation, would be disastrous especially because its built in central China. Large cities, nuclear power plants, and hydro projects are routinely considered prime military targets. Looking back at history, British have bombed Germany's Mohne and Eder dams during WWII and the US has bombed North Korean dams during the Korean War .
Another issue that will just be mentioned and not greatly elaborated on is the dam failures. Failure of a very large dam carries with it a much larger potential to cause death than any other major man made structure/facility. Due to sudden collapse, flood wave can be generated that can be very disastrous.
Finally, it has to be mentioned that in many democratic countries such a project as The Three gorges would have never been approved. Human rights of the people to be resettled and more importantly many intellectuals would have been taken into an account which can not be said to be the case with construction of Three Gorges in China. It can be comfortably said that the only reason project was ever allowed is because of Chinese Communist leadership, which lacks listening and debating. By controlling the media and news blackouts problems and devastations are not known and minimised from a full scale. Such a regime is determined to prevent the full truth from being revealed. If people speak against the decision they risk loosing their jobs or worse. This is all due to the one-party system (communism), where politicians have characteristics of authoritarianism, and no regard for individual allowing no democratic discussion at all .
Responsibility of Civil Engineers is to provide people with suitable infrastructure that will allow people and societies they live in to carry out their activities. Societies should decide, preferably through democratic progress, whether they want development to progress or not . They should not be forced to accept development of any project.
Building of dams has many benefits that have been described most important of those is that they have potential for clean non polluting production of electricity and provision of water for sanitary purposes. In some parts of the world, such as China it can have a huge potential for preventing flooding. One of main drives for construction of Three Gorges Dam was flood prevention for 15 million people. If 1.6 million had to resettle, but 15 million people guaranteed that chance of flooding is one in a thousand many would argue for it to be a good idea.
Although there are number of benefits, it is mostly environmental impacts that concern majority of people. Because dams flood large amount of areas, it can affect ecological stability in rivers, especially for fish, local climatic conditions (i.e. extra water evaporating from the reservoir), and it can cause landslides and seismic activity. These are just some of many environmental issues. Social, economic and political aspects are of the same importance and must not be overlooked.
As long as adequate steps are taken to minimise the environmental impacts, making sure that environment can sustain the infrastructure, and people to be affected in majority agree to take resettlement compensation, it is a good idea to build dams, but perhaps not on such a large scale as the Three Gorges.