Flash floods – how to prevent them and limit damage

Why does the water become so powerful and so quickly during heavy rains? According to e.g. experts from the Center for Helmholtz in Potsdam, meteorologists cannot precisely determine when and how much rain will fall in a particular area during heavy downpours. In addition, a cubic metre of water weighs one metric ton, which makes it very heavy. Other factors are the erosion of damaged surfaces, which can be easily washed away by pressing water, and the ability of the soil to absorb, store and release water. Clay soils rich in colloids are the best, and those with a lot of sand are the worst.

To limit flood damage, consider earthquake-resistant architecture. The depth of the building’s foundations, its structure and materials should be chosen to cope with extreme flooding. Retention valves on sewage connections are helpful, preventing flood waters from flowing back into houses, sealing windows and doors, and securing fuel tanks used to heat houses. Instead of confining rivers, levees should be moved back to make way for floodplains – wide open green spaces that can serve as overflow reservoirs during floods.

According to researchers from Cardiff University and the University of Worcester, river barriers similar to those built by beavers can protect flood-prone communities by pooling water upstream and then slowly releasing it. These are leaky dams made of natural material such as trees, branches, logs and leaves.