9.9.4 Why does it flood? Floods are natural events that can cause serious damage to the environment and communities. The threat of floods is increased as human settlements are often built on floodplains . • Floodplains: • A floodplain is a flat area next to a river that gets covered by water during floods (see FIGURE6 ). • They form when rivers slow down in flat areas, depositing mud and soil called alluvium . This builds up the floodplain and other landforms like deltas. • Why we live on floodplains: • Floodplains ( FIGURE6 ) have fertile soil, making them ideal for farming. • In Australia, many of our richest farms and towns are on floodplains near rivers, making them prone to flooding. • Vegetation and flooding: • Clearing vegetation in catchment areas (areas that collect rainfall) increases the risk of floods. • Native plants help slow down water run-off, reducing the chance of flooding. Understanding floodplains helps us manage risks and protect communities.
FIGURE6 Flat, fertile floodplains are often chosen for farming and settlements due to their rich soil and easy access to water.
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A Tributary stream B Waterfall C Meander D Floodplain E Delta F Deposited sediment
G Mountains H Watershed
TOPIC9 Water in the world 301
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