'N VLOEDSKADESIMULASIEMODEL VIR DIE HERBEPLANNING/—STRUKTURERING VAN 'N VLOEDVLAKTE / A FLOOD DAMAGE SIMULATION MODEL FOR THE REPLANNING/RESCHEDULATION OF A FLOOD PLAN

In South Africa a start was made, during research into the effects of floods during the seventies to developing a set of flood damage functions based on actual floods. Repired follow-up research was not continued during the eighties. For various reasons flood damage, based on actual floods, is underestimated and/or overestimated; a second method for estimating potential flood damages, namely the ex ante approach, was followed to compile loss functions based on potential floods. With relationships between the money value of direct flood damage to a damaged item (damage when an item was in physical contact with flood waters) and one or more characteristics of the flood, eg. depth of flood waters, duration of flooding, and the momentum flux of the flood waters, the money value of the direct damage that will be caused by floods of different sizes can be estimated before floods actually occur. This forms an integral part of flood damage simulation models. A geographic information system (GIS) approach was followed to develop a flood damage simulation model consisting of several interconnected data bases. The GIS model remders ot possible to estimate flood damage from three viawpoints (local, regional and national). Visual representations of the area, two- or three-dimensional, can be obtained on screen or on maps. In addition, the advantages of different combinations of flood control and flood damage control measures can be estimated by the GIS model, for examule land use manazement, flood protection, dam mananement and flood insurance.