On Monday, residents of Eugowra in New South Wales had to flee for their lives. They had only minutes to get to higher ground – or their rooftops – to escape what’s been dubbed an “inland tsunami” of water. This week, many other towns across western NSW faced renewed floods. For many people affected, the real shock is how unexpected it was – and how fast the water came. Their houses and land had never flooded, as far as they knew. What had changed?
This is an important question with a number of answers. When we make these assessments, we’re drawing on two sources: local knowledge and, increasingly, what flood maps tell us.
While tremendously useful, local knowledge has limits. Human memory is fallible and written records do not stretch back far. Flood maps also have constraints. That’s because floods can differ greatly depending on where the rain falls, at what intensity, and over what period of time. We will also have to redraw flood maps more often, as climate change brings more extreme weather. As climate change progresses, the atmosphere can hold more water. This supercharges atmospheric rivers – huge torrents of water carried above our heads.
