River Regime & Hydrographs (Edexcel IGCSE Geography)

Snow and ice melt leads to higher discharge - usually in the spring months

High temperatures increase evaporation and reduce river discharge

Higher rainfall in autumn and winter increases river discharge

Convectional rainfall in summer or hot, moist climates increases river discharge

Vegetation increases interception and infiltration leading to reduced overland flow and so lower river discharge

Deciduous trees lose their leaves in winter decreasing interception, increasing overland flow and river discharge

Concrete and tarmac in urban areas and built environments are impermeable leading to high overland flow - this is rapidly taken by drainage systems to the rivers/streams, increasing river discharge

Permeable rocks increase infiltration and percolation which reduces overland flow and decreases river discharge

Soils which are compacted or frozen reduce infiltration, increasing overland flow and river discharge

Water taken for irrigation and domestic use decreases the river discharge

Dams control the flow of water, so can both increase and decrease river discharge

Reservoirs experience higher levels of evaporation which can decrease river discharge

Steep slopes increase overland flow which leads to increased river discharge

High drainage density leads to increased discharge, particularly after a rainfall event