QUANTIFYING ECONOMIC AND HYDRAULIC FLOOD RISK

Traditionally flood management policies have been based on a design standard approach, in other words a degree of protection (i.e. 1 in 20 year event) and have focused on the hydraulic aspects of flooding. So if you built your levees high enough, or your pipes big enough you would be OK.

Increasing community expectations, decreasing financial resources and uncertainty in future weather conditions mean that developing the “best” solution is challenging, as many of the goal posts are moving.

Flood analysis needs to consider the consequence of the flood events with different probability of occurrence and develop the best alleviation measures over a given period of time. Understanding the hydraulics of the flood is critical, and something already done very well by hydraulic models. Equally important is the consequence, as this is what the community react to, and what influences the post flood recovery cost.

This paper will discuss how hydraulic models can be used to develop an Estimated Annual Damage (EAD) value which can be used to compare different flood management strategies, allowing Officers to make economically efficient decisions while maximizing the protection of their communities.