Evaluation And Countermeasures For Dike Safety Based On Flood Routing Numerical Simulation

Flood disaster is one of the most serious natural disasters in China, which happens with high frequency and high loss, and affects the sustainable development of society. In recent years, with the flood disaster loss increasing, a new strategy defined flood management has been proposed instead of flood control through summarizing the relationship between economy development and flood disaster. Among which, dike risk management is one of the important tasks for flood management. Formerly, when people made the flood control plan, they always focused on building and neglected management, which caused the dike being constructing more and more higher. Once dike burst happens, the flood disaster will be more serious. Therefore, it is necessary to identify and evaluate the flood control risk of dike by using scientific methods, and then put forward responses for handling the adverse consequences. The purpose of dike risk management is to improve capability for flood management. In this paper, the risk analysis for dike safety and emergency measures for dike burst is studied based on flood routing numerical simulation in the lower reaches of Liaohe River. The main research work is outlines as follows:(1) The flood routing numerical simulation model is established by using MIKE21 in the study area, and the flood hydrograph is simulated at the different designed frequency of flood. Then the effect of production dike on flood carrying capacity is analyzed. Through comparing the simulated result of MIKE21 model with that of MIKE 11 model, the simulated flood hydrograph is considered to be reasonable, and can be used in assessing the risk of dike safety.(2) A model of analyzing the overtopping failure risk of dike is established based on the method of fault tree. The simulated water level is taken as basic condition, and the uncertainty of river flood, Randomness of wind speed and ambiguity of dike burst is considered in this model. Then the dike safety in the lower Liaohe River is evaluated by using the proposed model to predict the dangerous condition of existing dike engineering. Simultaneity, the effect of factors including running time, river regulation and dike management are also analyzed. The result can provide decision supports for improving flood control capacity of dike.(3) Combining the evaluated result of dike safety with the achievements of flood hazard map and flood control system, the emergency measures for dike burst is proposed in the study area, which can be summarized as:'roll, reduce, block, evacuate, drain, enclose and rebuild'. The each measure is also explained in detail. Then taking the L99 dike section burst as case study, the corresponding measures are advanced to decrease the flood loss. From the example analysis, it can be deduced that the emergency measures based on flood hazard map is exercisable for real-time flood rescue.Finally, the conclusions are given and some problems to further study are discussed.