Flood fatality hazard and flood damage hazard: combining multiple hazard characteristics into meaningful maps for spatial planning

Abstract

Abstract. For comprehensive flood risk management, accurate information on flood hazards is crucial. While in the past an estimate of potential flood consequences in large areas was often sufficient to make decisions on flood protection, there is currently an increasing demand to have detailed hazard maps available to be able to consider other risk-reducing measures as well. Hazard maps are a prerequisite for spatial planning, but can also support emergency management, the design of flood mitigation measures, and the setting of insurance policies. The increase in flood risks due to population growth and economic development in hazardous areas in the past shows that sensible spatial planning is crucial to prevent risks increasing further. Assigning the least hazardous locations for development or adapting developments to the actual hazard requires comprehensive flood hazard maps. Since flood hazard is a multi-dimensional phenomenon, many different maps could be relevant. Having large numbers of maps to take into account does not, however, make planning easier. To support flood risk management planning we therefore introduce a new approach in which all relevant flood hazard parameters can be combined into two comprehensive maps of flood damage hazard and flood fatality hazard.

Room for Rivers: Risk Reduction by Enhancing the Flood Conveyance Capacity of The Netherlands’ Large Rivers

“…Based on the simulated flood extent and depth, the consequences of each flooding scenario were calculated in terms of economic damage, number of people affected and number of casualties [3,4] using the standard damage model for The Netherlands [24]. The simulation results were used to derive the required flood hazard maps for the European Floods Directive [25], to compute the economically most efficient protection standards for all embankments in The Netherlands [3], for the revision of The Netherlands' flood protection standards [4], and to develop flood hazard maps for spatial planning [26].…”

Beyond Flood Hazard Maps: Detailed Flood Characterization With Remote Sensing, Gis and 2d Modelling

“…In Japan, information on flood characteristics such as the flow rate of flood waters, speed of propagation to downstream areas, inundation duration, and increase rate of inundation depth at water storage areas are added to flood hazard maps as an effective way to encourage residents to take evacuation actions on an appropriate timing (MLIT, 2005). In the Netherlands, flood probabilities and flood characteristics such as flow velocity, rising rate, maximum water depth, flood duration, and their combinations are used to calculate two objective measures of flood hazards namely, the flood fatality hazard and the flood damage hazard (de Bruijn et al, 2015).…”

Implementing new flood protection standards: obstacles to adaptive management and how to overcome these

“…With this criterion on social equity the protection standard was raised in order to achieve a fatality risk not exceeding 10-5/yr. Or in other words: the individual probability to die due to flooding should be less than 1: 100.000 per year [17,21]. Thirdly, in cases where a flood might cause societal disruption because of vital infrastructure being hit, cascade-effects, large numbers of fatalities, or long-term disruption of public life or business, the protection standard was raised further.…”

“…The underpinning of the thus founded protection standards relied on 1) cost-benefit analysis [20], 2) estimates of Flood Fatality Hazard [21], and 3) loss-oflife modelling per breach location and related expert judgement on cascade effects and consequences for vital infrastructure of each breach. In the cost-benefit analysis DOI…”

“…By assuming a certain effectiveness of evacuation and the application of a lossof-life model with mortality curves for water depth and water level rising speed, we could calculate the probability of drowning of a hypothetical person on every spot in the country [21]. By backward modelling the acceptable probability of breaching could then be established for each embankment stretch.…”