Sustainability in civil engineering would therefore mean to have balance between these three objectives, both now and into the future.
Let us take an example of the Three Gorges Dam project in China, which clearly illustrates that, lack of sustainability in Civil engineering projects could undoubtedly cause serious social and environmental issues. The proposal for a dam on the Yangtze, the world's third largest river, took shape Eighty years ago and since then it had been in the plans of the Government of China. The Three Gorges dam which in under construction currently is expected to be completed by the year 2009. Upon its completion the dam will be around 600 feet high, 1.5 miles long, and will form a reservoir which is 400 mile long, in the middle section of the Yangtze River. This is supposed to be the largest dam project in the world. This project is expected to meet four important objectives, Flood control, Generation of Power, Improved navigation on the Yangtze River and Fresh water accessibility. The reports released by the Chinese government and the concerned contractors of the Three Gorges Dam do not emphasize on the negative impacts caused by this project on the environment, atmosphere and social life. The most important impacts on the environment include deforestation, excessive emission of greenhouse gases, loss of aquatic life and severe impact on water quality. When the project is completed there would be a dynamic change in the silt levels and water temperature. Due to this extensive silting the anticipated positive benefits of improved navigation and Energy production are questioned. The Yangtze River is known for its extreme silt content. The silt settled down at the bottom of the reservoir would slow down the water flow. Thus, the silt which has formed upstream would reduce the navigation. And the silt that gathers near the dam may reduce effective power generation. The environmental changes that occur during the construction of the Three Gorges Dam would also cause a significant loss of the aquatic, plant and wildlife species. The Chinese Academy of Sciences Mountainous Disaster and Environment Institute has divided the natural and social ecology and environment into 78 subsystems varying from climatology to terrestrial fauna. According to a study conducted by them, the report says that the Three Gorges Dam would affect nine subsystems positively, six of them neutrally and sixty three subsystems negatively. While we see the above environmental implications of the Three Gorges project, the social implication of this project involves the relocation and resettlement of more than a million people from the Yangtze basin area. The Chinese government initially estimated this number to be lesser than 0.75 million while the real number lies somewhere between 2-4 millon. The problem that might arise due to this is, most of the people who will be relocated are peasants and they are to be compensated by providing them with new lands. However, the lack of land in the area and high erosion levels make this impossible. Therefore, The Three Gorges dam which