The Issue Of Rising Sea Level In London
Recently, the impact of global warming has caused heavy damages to our lives such as sea level rise, global climate change, and so on. Can you imagine believe it or not sea level rising is more serious than people think. Global warming is causing Antarctic ice to melt, causing water levels to rise and cover islands. This essay reviews some valuable researches such as Intergovernmental Panel on Climate Change. It shows us the sea level is going to rise up to 1m (39 inches) by 2100. In fact, most of small islands and some capital cities which are located near the sea or ocean are in trouble of being under water sooner than we expect. It is said that London, which we focus on, is one of the examples of the cities which face the risk of sinking. To protect London from rising sea level, before it becomes too late, environmental agencies, engineers and leading flood experts express three main solutions; raised coastal defense, barrier islands, and control of tide.
The risk of flood for coasts and estuaries which are exposing to flood hazards from rising sea level, storm surges, and the possibility of tidal wetlands are increasingly known globally. Therefore, it is important to protect our lives and our cities. In order to reduce the tidal wetlands from peal water levels during storm tides, the first major step is that using a two-dimensional hydrodynamic model for a 300-ha intertidal marsh so that the peak water level would be reduce greatly between individual flood and the locations in the marsh. Then decide which tides are attenuated. Next, they confine the marsh size by dikes or other structures to block and set the water level. But if the flood duration is long relative to the marsh size, the peak water level would be affected. After setting up the water level, build a marsh which has 6 to 10 km of width to avoid blockage effects for the storm tidal cases. It starts to decrease by more than 0.2-0.4 when the attenuation rate which is the variations in between different locations in the marsh and between tides with varying high-water levels are occur.
The second major step is sluices gate which is one of the most effective ways to protect the land from rising sea level. Sluices gate is as controlling and releasing as canal water. First, the sluice is opened when both water level of the inside gate and outside the gate is the same. Next, store the water in the reservoir until a certain level is reached. Then sluice starts to open. As soon as a certain level is reached, the sluice starts to close so it prevents the release of large amounts of water. At the same time, the sluice functions as a dike. Therefore, sluices can reduce the water rising level and decrease the risk of water overflow effectively.
Last but certainly not least, barrier islands can effectively prevent cities from being threatened by rising sea levels. At first barrier island was part of the ocean. It used to be a beach dune on the mainland. When transgression occurred, they gradually separated from the mainland. At the end of transgression, the area behind barrier islands became lagoon or tidal flat. Barrier Islands continue to grow upwards as sea level rises. The interaction of wave and bank current is a necessary condition for the formation of barrier island deposits. There are 2149 barrier islands across the world, spanning 20783 km (12914 miles) of the coastline. 74% of the islands were found in the northern hemisphere. Surprisingly, 12.7% of barrier islands have 272. London's Thames, for example, is a good barrier island. According to Brown, Sally, Haigh, Ivan, Nicholls, Rober (20015), the Thames Barrier spans 520 meters across the Thames near Woolwich, protecting 125 square kilometers of central London from tidal floods. It has 10 steel doors to rise across the Thames. When lifted, the main gate is a five-story building, as wide as the opening of the tower bridge. Each main gate weighs 3,300 tons. Close barriers in storm conditions to protect London from flooding. It may also be closed during the Teddington Weir high flow period to reduce the risk of flooding in some parts of Western London, including Richmond and Twickham. Then the Thames barrier will be closed at high water levels until the water level downstream of the Thames barrier falls to the same level as that upstream. This is a hosting process that provides different situations and takes about five hours. Then the Thames barrier is opened to allow upstream water to flow into the sea with outward currents. The Thames River Barrier, a well-developed, well-extended barrier island with fewer tidal channels, effectively blocks sea water. It is a good example of protecting cities from the effects of sea level rise.
In conclusion, no one can deny the fact that climate change has already caused sea levels worldwide to rise and this trend is continuing. Moreover, there is evidence that shows the rate of sea levels have been increasing in the last recent years. According to a lot of researches, some solutions to adapting coastal cities to rising sea levels are reviewed which are different depend on climatic condition of each city. But, under no circumstances should we forget that human factor plays an important role in the process of preventing. As mayor, city designer, city planner and other related major, it should be considered that the emphasis on promoting community education about the flood threat and devoting special attention to vulnerable populations have to be placed on the top of all protecting programs. Today a little time is left to reduce and stop global warming. So, while specialists are searching for finding more solutions of preventing cities from rising sea levels, we as human being should go to the way of being sustainable and solve this huge problem from the root. Finally, all people around world should act as soon as possible because it is an international problem.
