Is rare extreme or is extreme rare?

What is extreme? How is it defined for the hydrographic events we deal with most, i.e. droughts and floods?

What happens if the projections for climate change are true? As the number of extreme events increase and they stop being rare, do they stop being extreme? Are the old extremes the new norm?

Maybe not something to worry about now but for the latest generation of hydrographers it will probably be something they will have to consider in both their work and lifestyle.

We look at extreme events their definitions, and a 100-year or greater return period seems to be the winner, as well as the practical issues in trying to calculate a specific value for some of the more common definitions with the data that we collect.

We also look at some of the ways that hydrographers might plan to mitigate and deal with extreme events).

• Read the paper in Australasian Hydrographer April 2020
• What is an extreme event? Appendices (download separately)