Flood Risk Management System Based On GIS

Because of the special geographical and climatic characteristics, China is a country in which flood is one of the severe disaster and occurred frequently. Flood in China has several characteristics as follows: the distributing area is far and wide, the frequency is high, the relationship between "Flood" and "Waterlog" is severe, the duration time of high water level in the river is enlarged and the losses is huge.After the foundation of the People's Republic of China, larger scale flood control works were built, and the flood control engineering system of China was set up. This system operates on flood fighting and lives saving and properties protecting. Though the flood control engineering system improved the flood control standard and reduce the frequency of flood inundation and enlarger the protected area, but at the same time, the risk of dike broken and dam failed were added. Moreover, people found that human living environment become worsen increasingly and the river ecosystem was destroyed. In thinking those issues, people were quite aware of that it is impossible to get rid of the floods. Because of the floods is a nature phenomena, human only can lighten and avoid the losses of the flood instead of eliminate it. The concept of flood risk management was put forward according this.Flood risk management includes identifying, estimating and evaluating flood risk. Moreover, using law, administration, economic, technology, education and engineering to regulate the relationship between human and nature in order to achieve the maximum safety and sustained development of human.Flood risk management is a continuous, circular and dynamic process. It is consist of building target, identifying flood, estimating flood losses, evaluating the risk of flood losses, selecting scenarios to reduce flood risk, making decision to flood risk management, writing plans for flood risk management and evaluating the effect of the decision.In recent years, the development of computer technology especially theGeographical Information System (GIS) give the powerful support to the management of flood risk information. GIS is a computer system that can input, output, save, query, analyze, display and refresh the geographic data.Because d eveloping G IS application independently is very difficult and developing GIS application based on the language which provided by the commercial mature GIS is very limited, so the c ombining developing style using GIS and mature visual developing language such as Visual C, Visual Basic and so on is becoming dominating style. The advantage of this style is it can exert the good capabilities of GIS which can management and analyze graphical database and exert the high-powered and convenient properties of the v isual developing languages. Using this style to develop application, it can't only improve the developing efficiency, but also can make the application have good interface, powerful database, good stability, easy to transplant and convenient to maintenance. It can exert these advantages to use OCX technology and GIS packages to develop application.GIS can be used in flood risk management system as follows: basic information management, flood risk calculation, flood risk map making, flood risk information query and flood losses evaluation and query.Based on the distinguish from the main factors effected on the flood, the flood inundation area, water level, inundation duration time, flood velocity were calculated from the 2-D numeric hydrodynamic model. Combined with the society economy data and the location data of each county, the flood losses were estimated. Using the mature product MapX, Visual Basic, Visual Fortran and SQL Server, a flood risk management system based on GIS was developed and used in the lower reach of the Yellow River. The whole system is a computer system for flood disaster mitigation decision and flood risk management which includes basic information management, flood risk calculation caused by dike broken, flood risk map making, flood risk information...