This summer, many parts of the world have seen devastating flooding, from New Orleans and New York, to the UK, Germany and Belgium. Professor Hannah Cloke of the University of Reading is a natural hazards researcher and hydrologist, who spends her time trying to prevent these terrible losses. She models where flooding is likely to happen and advises governments. Here she talks to Jim al-Khalili about how her work and how her fascination with the water on the earth goes back to her childhood