Theory question 205
Rivers and River LandformsWrite explanatory notes on any two of the following (a) Flood plain (b) Hydrological cycle (c) River erosion
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Flood plain: wide, flat land on either side of a river in its lower course; built of alluvium spread when the river overflows its banks during floods; fertile soils; features include levees, meanders and ox-bow lakes; examples Niger and Benue valleys, Ganges, Mississippi; useful for farming but liable to floods.
Hydrological cycle: continuous circulation of water: evaporation from seas, lakes and land, transpiration from plants; condensation into clouds; precipitation as rain or snow; run-off into rivers and back to the sea; infiltration and percolation into groundwater; diagram helps.
River erosion: processes of hydraulic action, corrasion (abrasion), attrition and solution (corrosion); vertical erosion in the upper course forms V-shaped valleys, gorges, waterfalls, potholes; lateral erosion in the middle/lower course widens valleys and forms meanders.
Choose two and explain each fully with examples.