Environmental Sustainability in the Eyes of Civil Engineers
Civil Engineering as a field is best described in the most basic form by the American Society of Civil Engineers organization as “the design and maintenance of public works such as roads, bridges, water and energy systems as well as public facilities like ports, railways, and airports.” To go into greater detail, today’s engineers deal with the careful and complicated planning, design, construction, and maintenance of most infrastructures of today’s world. These infrastructures include transportation systems; basic water systems such as waste water/ fresh water treatment, dams, flooding control, and irrigation systems; environmental systems including pollution control and things of that nature; and all kinds of structures. All of these private and public works have a direct effect on the environment and careful considerations are made in the planning and design in accordance to certain laws and codes. Every field of engineering deals with working with, and sometimes altering the environment is some way or another. And it has become a main concern for engineers to create more sustainable ways of going about their practices. They are constantly trying to come up with newer and more efficient techniques of working with the environment as opposed to against it. This can be a very challenging task considering the main goal of engineers is to make an environment that is better and efficient for human lives. Sustainability has always been something engineers try to consider but it has become more evident in the 21st century that it needs to be included in the main goals of a project.
An example of one of the systems that engineers create and manage that has a large effect on our natural environment is our water systems. Almost all of our rivers and streams are affected by dams. There are 6,375 dams in the United States alone, which is about 13% of the world dam population (www.dams.org). Building a dam on a river has many long and short term effects on the natural water systems and the surrounding environments. The system of dams in the world has fragmented the river systems drastically, impacting various wildlife and vegetation ecosystems and the natural flow of the rivers. Every river has its own flood plain and natural flooding patterns, which have their own benefits to the ecosystem, and building a dam greatly impacts and changes this. But this is also one of the goals of the engineers building a dam, to control the river and its flow of valuable water for reasons such as irrigation and flood control. And part of their job is to look at both sides; the positive benefits and the negative effects the dam would have on the area. If the benefits outweigh the effects, then the dam is built. And this is where they have to factor in sustainability.
Flooding is the most common hazard in the United States and can occur on a small scale, affecting only a town or two, or extremely large scale, affecting entire river basins and multiple states (http://www.fema.gov/hazard/flood/index.shtm). It causes major damage to life and property, plus water damage is very expensive to repair. Many American cities and towns are built along and beside rivers to maximize their potential in trading and transporting goods. The downside of having a city next to a large river is the flooding of that river into the city. And chances are that the city and probably other towns are located in the natural flood plain. So it is in our human nature to modify the system so that it works better for us. Flood control dams are built for these reasons. They are often built along upstream tributaries of a larger river so that they will temporarily trap excess rain and runoff produced by a heavy rain. Then the water is slowly released through the dam. This greatly reduces the amount of water that would travel through the main river course, resulting in less flooding in that particular river basin. Engineers also take other routes in flood prevention. Many channels that run through large cities are modified to get water through the area as fast as possible without the consequences of a flood. Such modifications include straightening the channel, adding concrete barriers, or just simply rerouting it to flow out of the populated area. Both of these methods have an effect of the natural flow and the ecosystem of the river, both upstream and downstream.
Almost all of the dams in the western United States are primarily used for irrigation purposes to provide the much needed water to the massive farming and the large populations in these flat, but dry regions of the country. Without a dam, the only accessible water source is ground water and there is only so much that can be accessed. Once that’s gone, it’s gone forever. So the solution seems obvious to an engineer, who is a problem solver. Build a dam to hold back the accessible water that can be used for whatever the need happens to be. Dams also have other benefits which help for the sustainability argument, mainly being that they are used to produce hydroelectric power. Hydroelectric power is considered clean power, meaning it has no negative impact on the environment, and it is renewable. The U.S. is the largest generator of hydroelectric power, in which dams provide 8-12% of the nation’s power needs (fema.gov).
Figure 1: American Dam Uses.
Source: National Inventory of Dams, 2005.
Engineers have to factor in the many negative effects of dam building also. There would be a major impact on the river’s surrounding environment, including the land and the people living along the river, along with the wildlife in and around it. Sometimes many people have to be displaced from an area in order to have a reservoir. Many animal’s habitats and ways of life are altered as well. In the Loire Valley in France, for example, salmon were very abundant and about 100,000 migrated up the river, and in 1997 only 389 were counted traveling upriver (Marks, 2007). Also, in Maine, when the Edwards Dam was taken down in 1999 on the Kennebec River, biologists observed the return of many species of animals that originally resided there, such as the striped bass, Atlantic salmon, and the bald eagle (Marks, 2007). But it is important to point out that taking down a dam does not simply return the ecosystem back to normal. It is a very complicated process that involves many other factors such as all the sediment built up behind that dam that would be released into the river. The removal of dams is becoming more common than the building of them these days and will probably follow that trend in the near future.
So in this particular engineering example, it is the engineer’s job to weigh the benefits of building a dam against the negative effects if has on the environment of the area. They have to come up with sustainable arguments that support the project. Such arguments include if the dam is going to help the area’s environment more than hurt it and if it is worth the cost and effort put forth to complete the complicated project. And as mentioned earlier, if the benefits outweigh the negative effects, then the dam is built.
*Not completely finished. I want to add another paragraph or so about things engineers are doing now to become more sustainable, and then a conclusion.*
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