River Systems and Processes
Rivers transform landscapes through distinct upper, middle, and lower courses, each with characteristic features. The upper course is steep and narrow with vertical erosion creating V-shaped valleys, waterfalls, and rapids.
River transport works through four methods: solution (dissolved chemicals), suspension (tiny particles), traction (large stones dragged along), and saltation (stones picked up and dropped repeatedly).
The middle course shows deeper channels with slight bends and interlocking spurs forming broader valleys. Meanders develop as water flows in a corkscrew pattern, with fastest currents on outer bends undercutting banks whilst inner bends build up point bars.
Top Tip: Remember that velocity is actually fastest in the lower course despite the gentler gradient - this catches many students out!
River flooding results from heavy rainfall, tidal surges, raised groundwater levels, and saturated soil that can't absorb more water. Antecedent rain (previous rainfall) makes flooding more likely by reducing soil permeability.