A method for evaluating flood hazard and flood risk of east Bangkok plain, Thailand

Abstract

A new method for estimating flood hazards was developed in this study for flat and low-lying areas wherein floods have low flow velocity, large depth and long duration. The hazard was computed as a function of flood depth and duration, not only depth as in the past. The study area of 624 km2 in suburban Bangkok, Thailand, was divided into small grids, each 200 m by 200 m. Because flood depth and duration have different dimensions, this new method categorised the depth and duration into four groups of small, medium, large and largest magnitudes represented by the integers 1, 2, 3 and 4, respectively. The depth integer and duration integer of each grid were weighted by the factors μ and (1 − μ), respectively, and summed up to obtain the flood hazard indicator. The factor μ was assumed to be between 0 and 1 and adjusted by trial and error until the computed hazard satisfactorily satisfied the hazard estimated from field and questionnaire surveys. For flood damage vulnerability, an established methodology was applied considering the vulnerability as a function of population density and land use assets at risk. By multiplying the computed hazard and vulnerability, the flood risk maps of three return periods were constructed.

Comprehensive Assessment of Flood Hazard, Vulnerability, and Flood Risk at the Household Level in a Municipality Area: A Case Study of Nan Province, Thailand

“…The flood hazard was calculated by using Equations (1) and ( 2) in which the weights α, β, and µ representing flood duration, depth, and velocity, respectively, were systematically determined by AHP. In the other previous studies [17,18,20], the weights α, β, and µ for flood duration, depth, and velocity, respectively, in Equation (1) were specified by the researchers according to their experiences without using AHP. These weights could be subjective or questionable.…”

“…Previous studies [17][18][19][20][21][22][23] considered flood hazard as a function of flood depth only or flood depth and velocity. This study considered all parameters including flood depth, velocity, inundation duration, and their weights.…”

Assessment of Urban Flood Risks of the Cities Using Entropy-Vikor Methods in Türki̇ye

“…Flood risks were evaluated regarding number of floods, population density and number of buildings, flood protection area. In preliminary works, flood durations, depth-velocity were considered [33]; population, capacity, exposure [34]; only flood vulnerability [35]; mortality, economical and agricultural issues [36]; social and economical metrics [37], resilience [38].…”

Editorial

“…■ Combining hydraulic modelling with partnership working: towards practical natural flood management (Norbury et al, 2019). ■ A method for evaluating flood hazard and flood risk of east Bangkok plain, Thailand (Tingsanchali and Keokhumcheng, 2019). ■ Flexible adaptation planning process for urban adaptation in Melbourne, Australia (Radhakrishnan et al, 2019).…”