Infiltration
Infiltration is the downward movement of water from the soil surface into the soil profile. The infiltration rate depends on soil texture, structure, initial soil moisture, and vegetation cover. Sandy soils have high infiltration rates while clay soils have low rates due to smaller pore sizes.
Real World
After the 2015 Cumbria floods in northwest England, investigations found that heavily grazed upland soils had severely reduced infiltration capacity compared to nearby forested areas, causing rapid overland flow into the River Eden.
Exam Focus
When explaining flooding, always link low infiltration rates to increased overland flow — examiners expect a chain of causation, not isolated facts.
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