Determining the benefits of flood mitigation measures in the lower Orange River: A GIS application

When topographical, hydrological, hydraulic and economic information is int egrated with the aid of a flood damage simulation model, the total mean ann ual flood damage can be estimated. With the total mean annual flood damage known, it is possible to ascertain the benefits of several flood mitigation measures. These measures are normally implemented to reduce the physical e xtent of floods, relieve the effect of a flood on humans and the community and reduce the tendency toward flooding in different areas. It is not econo mically justified to implement measures to such an extent that they will pr event the total risk of flood losses. The benefits gained from flood mitiga tion measures should at least exceed the costs involved. Consequently, an o ptimal package of flood mitigation measures should be compiled where the ma rginal benefits are Equal to the marginal cost. The purpose of this paper is to identify relevant flood mitigation measures for the research area, discuss their benefits and drawbacks, after which t he possibilities for application in the research area are analysed.