Author(s): Jinghua Jiang; Qiuhua Liang
Linked Author(s): Qiuhua Liang
Keywords: Compound Flooding Copula Multivariate Analyse Correlation Flood Risk Assessment
Abstract: Can Tho, the economic hub of the Vietnamese Mekong Delta, faces challenges from rapid urbanisation and increasing flood risk. The flood-related losses are reported to account for 11% of household incomes. The city’s population is projected to surge from 1.4 million in 2021 to 2.5 million by 2035, highlighting a critical challenge to sustainable socio-economic development. The existing flood risk studies have typically focused on single driver such as rainfall or paired factors including rainfall and river flow. A survey conducted by the People's Committee of Can Tho in 2009 revealed that almost half of flood incidents (49%) were resulted from the combined effects of rainfall and high tides, while another third (31%) emerged from more drivers including rainfall, high tide and upstream flooding. This study aims to capture the simultaneous interaction of all major flood-driving factors, advancing beyond the limitations of the traditional single or bivariate flood risk analyses. By analysing a 32-year dataset (1981-2012), we explore and uncover the mechanisms of compound flood risk in Can Tho City: a complex interplay between rainfall and elevated river levels, the latter resulting from the upstream extreme discharges and downstream high tides. Multi-hazard risk analysis indicates strong temporal correlations between flood drivers, including a 16 to 25 days lag between upstream discharge and local water level, and a one-day lag in tidal influence, reflecting the propagation time to Can Tho. Building on the findings, a probabilistic framework combining C-Vine Copula modelling and statistical analysis is developed to quantify the correlations among these factors. This leads to the development of a comprehensive joint probability function for different flood scenarios, enabling a shift from traditional single or dual-factor analysis to an integrated approach that accounts for multiple flood drivers and their temporal relationships. The study provides an improved understanding of compound flood risk in Can Tho City and highlights the importance of adopting an integrated flood risk management strategy to better characterise complex flood risk to inform the development of effective risk mitigation strategies for the sustainable growth of the city.
Year: 2025