Abstract

Typhoons and rainstorms are types of natural hazards that can cause significant impacts. These individual hazards may also occur simultaneously to produce compound hazards, leading to increased losses. The accurate risk assessment of such compound hazards faces several challenges due to the uncertainties in multiple hazards level evaluation, and the incomplete information in historical data sets. In this paper, to deal with these challenges, we propose a risk assessment model called VFS-IEM-IDM based on the Variable Fuzzy Set and Information Diffusion Method. In particular, VFS-IEM-IDM provides a comprehensive evaluation of the compound hazards level, and a predictive cumulative logistic model is used to verify the results. Furthermore, VFS-IEM-IDM applies a normal information diffusion estimator to estimate the conditional probability distribution and the vulnerability distribution of the compound hazards based on the hazards level, the hazards occurrence time, and the corresponding losses. To examine the efficacy of VFS-IEM-IDM, a case study of the Typhoon-Rainstorm hazards that occurred in Shenzhen, China is presented. The risk assessment results indicate that hazards of level â ¡ mostly occur in August and October, while hazards of level â ¢ often occur in September. The risk of the Typhoon-Rainstorm hazards differs in each month and in August and September the risk gets the highest value, and the estimated economic losses are around 114 million RMB and 167 million RMB respectively.

Highlights

  • Assessing risk is an effective way to reduce the negative impacts on natural hazards and plays an increasingly important role in helping the decision maker in emergency management

  • We introduce the information diffusion method to deal with the incomplete data problem and combine the variable fuzzy sets theory to carry out dynamic risk assessments of compound hazards

  • Output: Dynamic compound hazards risk. 4: Identification of the comprehensive value of compound hazards level by variable fuzzy sets (VFS)-IEW; 5: for Sample index i = 1 to n, each Xti do 6: Based on the universes of monitor space, employing the normal diffusion function in Eq 10 to construct information diffusion matrix of sample D; 7: end for 8: Estimate the joint and conditional probability distribution based on Eq 12 and Eq 13; 9: Determine the input-output sets and model the fuzzy relationship based on Eq.15, estimate the vulnerability distribution by Eq.16; 10: The dynamic risk (Direct Economic Loss) of compound hazards can be quantified by Eq 17

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Summary

Introduction

Assessing risk is an effective way to reduce the negative impacts on natural hazards and plays an increasingly important role in helping the decision maker in emergency management. We emphasize that risk assessment of compound hazards should deal with the uncertainties caused by multi-indicators, the unknown probability distributions, the 55 incomplete information in historical data sets, and the dynamic property of hazards occurrence. We introduce the information diffusion method to deal with the incomplete data problem and combine the variable fuzzy sets theory to carry out dynamic risk assessments of compound hazards. – 1) We consider the uncertainties in compound hazards level evaluation and incomplete information in historical data sets, and propose a hybrid model, named as Variable Fuzzy Set and Information Diffusion Method (VFS-IEM-IDM), to deal with compound hazards risk assessment dynamically.

Dynamic Risk Assessment of Compound Hazards Based on VFS-IEM-IDM
Dynamic compound hazards risk
VFS-IEW dimension reduction model
Dynamic risk assessment model
Case Study
II III IV
Discussion
Findings
Conclusions
Huang: Towards Efficient Fuzzy Information Processing
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