Theory question 203
Rivers and River Landforms(a) Using appropriate diagrams, explain the process of formation of a (i) river capture (ii) waterfall
(b) Describe one way in which each of the two features above is useful to man
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(a)(i) River capture (diagrams before and after): a vigorous river with a steeper gradient or on softer rock cuts back by headward erosion through the watershed; it reaches and diverts the headwaters of a weaker neighbouring river; features: elbow of capture, wind gap, misfit stream (beheaded river)
(ii) Waterfall (diagram): where a band of hard rock lies across a river's course over softer rock, the soft rock is eroded faster; a steep step forms over which water falls; hydraulic action and abrasion form a plunge pool and undercut the hard rock, which collapses so the fall retreats upstream leaving a gorge (also formed by faults, hanging valleys, plateau edges)
(b) River capture: increased water in the capturing river for HEP, irrigation or water supply; wind gaps give routes for roads and railways. Waterfall: hydro-electric power; tourism; marks head of navigation/site for settlement
Label elbow of capture, wind gap and misfit.