Efficiency of private flood proofing of new buildings – adapted redevelopment of a floodplain in The Netherlands

Abstract

A number of cities in Europe's deltaic and coastal regions, such as the London metropolis, Hamburg and Dordrecht, share in part similar challenges such as (re)development activities and expansions onto floodplains and they recognize the need for new planning approaches to manage actual and future flood risks in these areas. The tendency is now to look for new ways to distribute responsibilities between different types of stakeholders, so as to take advantage of different initiatives over differing spatial scales, from the catchment level down to the individual building level. In this respect, there is a clear need to include resilience measures taken at the lowest spatial level as part of a top-down and bottom-up approach. This kind of measure comprises flood proofing of buildings and associated infrastructure as well as adapting building activities to the risk. The extent to which such measures will be provided will probably be dictated by micro and macro economic factors. However, as of yet information on their performance is limited, which particularly holds true for the Dutch context. Consequently, the economic efficiency of these technologies is unclear.In this paper a new database containing economic information involving the costs and benefits for implementing these measures is presented. Flood damage databases have been constructed from a synthesis of all data available from both secondary sources, such as the ABI and FEMA database, and from the real experience of floods. The data is built up from knowledge about the effect of flood water on both the fabric of the building and its contents. In order to investigate the efficiency of private flood proofing of buildings, benefit cost analyses for different building types and elevations are conducted for a case study in Dordrecht, the Netherlands. The benefit for each damage reduction strategy is calculated by estimating the difference in expected annual losses compared to the traditional way of building.

A review of damage-reducing measures to manage fluvial flood risks in a changing climate

“…Both studies have similar estimates for the costs of dry proofing (around €7500 for 1m), however, estimates for wet proofing vary considerably. This is because the wet proofing in the estimates for the United States relate to the wet proofing of an unfinished basement , whereas the estimate of Gersonius et al (2008) relates to the wet proofing of the first living floor, which is much more costly (over €17000).…”

Deconstructing urban flood damages: increasing the expressiveness of flood damage models combining a high level of detail with a broad attribute set

“…For the purpose of this project, new stage‐damage functions have been developed based on information from the Dutch building sector (Gersonius et al , 2008). Apart from stage‐damage functions, the model also incorporates damage functions based on flow velocities and flow duration.…”

Adapting to climate change: using urban renewal in managing long-term flood risk

“…For a case study of a floodplain in Dordrecht [18], the Netherlands, the benefit-cost ratio of the two strategies has been computed: retrofitting 'now' and retrofitting 'with normal renewal'. For this specific regeneration site (built in 1982), the exceedance probability of local water levels was simulated using the probabilistic model Hydra-B [21].…”

“…Annual flood damage is computed as the integral of the damage-probability function: E(S) = ∫ S(x)dP(x) (7) where E(S) is the expected annual damage, S(x) is the flood damage caused by flood depth x, and P(x) is the probability of flood level x. Normal building Permanent dry proofing Wet proofing Figure 5: Flood damage curves for terraced property with and without flood proofing measures undertaken [18].…”

“…replacing like for like). Useful research has been conducted in the field of post-flood restoration or repair of property components with flood resistance or resilience solutions (referred in this paper as 'reactive retrofitting') [17] and of flood proofing of new buildings [18]. Post-flood restoration generally comprises dry proofing the building by sealing or shielding, or wet proofing the building.…”