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?