Benefit versus cost analysis and optimal cost effective mitigation strategies

This report presents an assessment of the cost-effectiveness of flood mitigation strategies to residential buildings in Launceston Tasmania through a benefit versus cost analysis. The benefit versus cost analysis requires assessing loss both pre-and post-mitigation for a range of flood likelihoods with the difference being the benefit. The costs of the applied mitigation are then compared to the benefits with a benefit versus cost ratio of greater than 1.0 indicating an economically viable decision.

In the research presented here, the mitigation options were typically assessed as cost-effective when considering the damage to the residential buildings with the probable maximum flood extent. An important modelling assumption was to assume that the existing levee system that does provide a level of flood protection to Launceston was not in place (i.e. the City was unprotected). The results here are also only for one catchment and its behaviour and also for the building stock in Launceston. The use of temporary flood barriers around the area with the highest flood hazard was the most cost-effective measure.