@article {bnh-7196, title = {Benefit versus cost analysis and optimal cost effective mitigation strategies}, number = {598}, year = {2020}, month = {08/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

This report forms part of the output to a research project entitled {\textquoteleft}Cost effective mitigation strategy development for flood prone buildings{\textquoteright} within the Bushfire and Natural Hazards Cooperative Research Centre. The motivation for this project arises from the experience and observations during the recent flooding in Australia in 2011, 2013 and 2015, which caused widespread devastation in Queensland. A fundamental reason for this damage was inappropriate development in floodplains and a legacy of high risk building stock in flood prone areas. The BNHCRC project aims to address this issue and is targeted at assessing mitigation strategies to reduce the vulnerability of existing residential building stock in Australian floodplains.

Previous project steps towards achieving this goal have included the development of a building schema to categorise the Australian residential building stock and a literature review of mitigation strategies developed nationally and internationally. The review categorised strategies into elevation, relocation, dry floodproofing, wet floodproofing and the use of flood barriers. Five typical storey types which represent the most common residential buildings in Australia have been selected to evaluate the above mentioned mitigation strategies.

\ Each mitigation strategy has been costed through engagement of a professional quantity surveyor and the application of the mitigation strategies and resultant reduction in susceptibility of damage has been quantified in the form of vulnerability models for mitigated storey types.

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 damage to the rersidential 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 behavior 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.

Work will continue with cost versus benefit analyses planned for other locations with different building stock configuarations and different catchment type behaviours. The result will be an evidence base to inform decision making by government and property owners on the mitigation of flood risk. The evidence base will feature information on the cost effectiveness of different mitigation strategies and optimal solutions for different cases of building and catchment types.

}, keywords = {benefit, buildings, cost analysis, Flood, mitigation, strategies}, issn = {598}, author = {Maqsood, T and Dale, K and Martin Wehner} }