Urban precipitation, surfaces and catchment characteristics; impacts on drainage basin storage
Cities replace soil and vegetation with hard surfaces like roads and rooftops. Rainwater can no longer soak into the ground, so it flows away much faster and in greater volumes.
Real World
When Storm Desmond hit Carlisle in December 2015, the city's high proportion of impermeable surfaces meant surface runoff reached the River Eden far faster than in upstream rural areas, amplifying peak discharge and worsening the historic flooding.
Exam Focus
Use precise hydrological vocabulary: 'impermeable surfaces reduce infiltration rates, increasing overland flow' scores more than 'water can't soak in'.
Essay Framework
Use PEEL to structure every paragraph. Tap each step for guidance and an example.
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