Study On The Theory And Method Of Comprehensive Analysis And Intelligent Assessment Of Flood Disaster Risk

Flood disasters are among the most frequent and devastating types of disasters over the world. Worldwide statistics indicate that continuously increasing flood damages and losses of human lives remain at high levels.Therefore, it is necessary to analyze flood risk to ensure healthy and sustainable economic development, and flood risk assessment has become worldwide one of the hot issues in the field of natural science and technology. And the flood disaster system is an open complex giant System with highly nonlinear, dynamic and complex uncertainties, including the disaster-inducing factors, disaster-breeding environment, hazards-bearing bodies and flood disaster loss, and the problmes in the system become increasingly complex and coupled problems from low-dimensional to high-dimensional. Undoubtedly, according to risk analysis and risk management of this complex system, regardless the classical control theory or traditional mathematical methods, we would likely encounter much trouble, such as whether information is uncertainty, whether the models are reasonable and reliable, whether the data is complete and the integrated system is universal. Moreover, development trend of related research has rendering out "from low dimension linear to complex high dimension nonlinear","from single scale to multidimensional spatio-temporal scale","from single stories to combination stories","from single variable to multiple coupled variable" and "from certainty to uncertainty", so urgent need is to propose and develop new theories and methodologies. Based on coupling complicated idea and complex system integration approach, a variety of complex coupling evaluation model were proposed in this article and then applied to the study of flood risk comprehensive analysis and intelligent evaluation under uncertainty. The aim of this article is to enrich and develop technical route of the establishment of flood risk analysis index system, determination of integrated weight and establishment of evaluation methods, then to reach the realization of flood risk identification, diagnostics, evaluation, and incomplete information under complex conditions as well as fuzzy risk analysis under incomplete condition, hence to provide scientific decision support for flood risk management and disaster prevention and mitigation integrated emergency plans. Specifically, the main research focus of this arcticle are flood hazard identification, flood vulnerability diagnosis, flood risk comprehensive assessment, flood risk fuzzy analysis and flood disaster intelligent evaluation, and the main research contents and innovations are as follows:(1) For the flood classification indices are uneven distribution, cross-serious and their comprehensive weight are hard to calculate and so on, the sensitivity coefficient was used to combine the subjective and objective weights into integrated weights, then fuzzy clustering iterative model with integrated weights was proposed for flood classfication. Then adaptive chaotic differential evolution algorithm (ACDE) was proposed for global search of the optimal fuzzy clustering center and sensitivity coefficient in the combined weight fuzzy clustering iterative model. Case study shows that the proposed classification method is reasonable, reliable, robust, which can effectively deal with flood classification indexes under uncertainty and ambiguity, and has good application value in sorting, evaluation and decision-making problems with no evaluation criteria.(2) For there are incompatibilities and uncertainties in the flood vulnerability assessment index system, based on multi-attribute decision making theory and method, we combine and improve the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Grey Correlation method (GC) into IGC-TOPSIS for dynamic comprehensive evaluation of disaster loss caused by flooding. Research shows that IGC-TOPSIS is reasonable and flexible, and it is able to describe the closeness from the position and shape of the similarity to the ideal solution and make full use of knowledge and information, to better tap the inherent data law, thus to improve the scientific of flood vulnerability assessment, and have has good application prospects in multi-index comprehensive evaluation.(3) Based on disaster system theory and taking consideration into flood formation, development and process on flood risk, as well as combined with hydrometeorological, socio-economic and natural environment statistics data and corresponding regulations and cases, the flood risk evaluation index system of flood diversion district as well as its evaluation standards were established. Then the analytic hierarchy process combined with trapezoidal fuzzy numbers (TrFN-AHP) was employed to determine the weights for evaluation indices. Meanwhile, considering the stochastic, fuzzy, gray and other uncertainties in flood disaster risk system and based on the intelligent analysis of generalized entropy theoretical framework, we proposed the flood risk comprehensive assessment model using the princple of maximum entropy and attribute interval recognition theory (AIRM-POME), to maximize the elimination of flood risk analysis in a variety of uncertainties, and the confidence criterion and eigenvalues equation are adopted to determine the flood hazard and flood vulnerability grades. Finally, according to the definition and quantification expressions of risk, we obtain the flood risk grades for each unit. Case study shows the proposed method has high reliability evaluation result, and it is a new method for flood risk comprehensive analysis and can be extended to other natural disasters risk analysis.(4) Traditional probability calculation method will encounter "small sample" incomplete information in practical applications, and there exists imprecise and uncertain theories bottleneck. In order to effectively deal with the uncertainty and incompleteness of flood risk, based on "information distribution" and "information diffusion" as the core of the fuzzy information optimization processing technology, we employ the improved interior-outer-set model (ⅡOSM) to obtain the possibility-probability distribution (PPD) risk results, which could not only clarify the objective facts of existing incomplete exceedance probability estimation under uncertainty and imprecision, but also provide a new idea for risk assessment to identify, accommodate, process and compute the fuzzy information. on this basis, the interval risk estimates were calculated, which was consistent the results by soft histogram. And furthermore, by combining PPD with fuzzy set cut technique, we got the conrresponding venture risk, conservative risk and maximum possibility risk values under different levels, thus can provide decision makers with multi-level, multi-valued risk information.(5) Considering the complex nonlinear relationship between flood disaster assessment indices and disaster grades, we adopt the support vector machine combined with ACDE for parameter optimization for flood disaster evaluation, and then set pair analysis theory, triangular fuzzy number, stochastic simulation technique are combined, thus to extend the discrete integer disaster grade to continuous and interval disaster grade. With the two methods above, we are able to analysis the related mapping rules between disaster evaluation model and actual disaster, overcome the difficulty of the traditional evaluation methods in establishing functional relationship between assessment indices and grades, overcome the technical bottleneck of calculating assessment results with oscillatory deviation, break the theoretical obstaclesthe of flood disaster grade high-precision and high-resolution dynamic comprehensive evaluation, as well as enrich and develop the theory and method of flood disaster loss comprehensive assessment under multi-level fuzzy conditons.