| 요약2 |
Water is the source of life and livings. It circulates along the cycle of water; sky, rivers and underground. So it is going through a long journey from the past to the present because it has been repeatedly rising and falling along the prosperity and decay of human civilizations. It has the duality of Janus when talking about flood and drought. Water is precious and generous with us in terms of irrigation while it is a dreadful and threatening existence to our life and safety in terms of reservoir. Traditionally, controlling the water is the most fundamental task for governing a Nation. The recent climate change and atmospheric abnormality such as localized torrential downpour have caused flood in urban areas with high population density. The last flood happened in the city of Seoul from July 26th to 29th of 2011 caused landslides in Mt. Woomyun and floods in some areas of Kangnam, which is the main commercial district in Korea. Besides Doorim stream was also overflowed. During that period, 67 buildings were carried away or completely destroyed and other 118 were totally flooded. The total number of inundated buildings was 27,357 and the damage costs were about 20 billion KRW. Therefore, it is necessary to gather some wisdom to have more safety measures to protect buildings from urban flooding which is occurring due to the climate change. At this respect, this article will review the problems of urban flooding from the past till now and propose some plans to cope with the future threats and damages caused by urban flooding and to protect buildings from it. The changes of urban structures and rainfall have a great impact on the increase of urban flooding. Most of the previous inundations were attributed to rivers overflowing due to low banks. But recently inundation damages are brought more with internal floods apart from the overflowing of rivers. Although the persistent expansion of emergency facilities reduced the number of inundated homes considerably, new types of inundations are taking place in urban areas and massive landslides occur due to localized rainfall. Firstly, to construct resistant buildings against urban inundations, Flooding Risk Map is needed for specifying the urban flooding danger zones. Once the basic latitude of urban flooding is determined by the frequency and size of flooding, the entire areas of flood-risk in an administrative district can be analyzed and designated by this pattern. The extension of flooding risk along a district is obtained from the flooding simulations on the risk model that uses surveyed inundation trace data. The data of flood-estimated districts can be used for urban planning. In addition, the classification of urban flooding districts into overflow risk, potential, and flood-free areas helps to implement land regulation, which can create basic safety measures against urban flooding. Above all, the criteria for the permission and approval of building construction within disaster areas should be reinforced. Also regulations should be strictly imposed upon floor space ratio, building-to-land ratio and building height in such areas. Major facilities or residential areas located in potential flooding districts of lowlands should be moved. If it is not realistically possible, underground facilities and basements should not be used in a way to reduce damage as long as they are lower than the estimated flooding altitude. In addition, building basement and residential spaces at ground level should be prohibited on the lowlands of potential flooding areas. As for the existing structures, institutional devices are needed to convert them into warehouses or garages. Furthermore, the entrances of buildings areas where have been previously flooded or have the possibility of flooding, should be constructed in Piloti type, so it can reduce flood damages. In conclusion, if legal and administrative measures against construction within flood potential areas are designated with the help of the classification of urban flooding districts into overflow risk, potential, and flood-free area, which is done based on the Urban Areas Flooding Risk Map, damages by urban flooding can be reduced considerably. |