River capture – meaning

• River capture may only occur where there are 2 adjacent rivers/ share a watershed
• One river has more erosive power than the other
• The more powerful river erodes vertically faster than weaker one thus flows at lower level than the other.
• The more power river erodes it’s valley towards the other river’s valley through head-ward erosion.
• Eventually, the powerful river joins valley of weaker river
• The powerful river diverts the head waters of the weaker river into its channel
• The diversion of the headwaters is called river capture.

• A pirate stream; this is the river through head ward erosion that captures water of another nearby river.
• Beheaded stream /misfit stream; this is the victim stream which has lost its waters due to capture.
• A wind gap; This is the dry valley of the beheaded stream below the point of capture
• Elbow of capture is the bend formed at a point where the headwaters of the captured stream flow into the capturing stream
• Gorge /incised valley; Undercutting of the pirate river near the point of capture due to increased water volume which results into renewed erosion producing a steep and deep valley.
• Knick point; a sharp break in the slope created near the point of capture due to rejuvenation.
• Over Fit River, this is the river that appears too big for its present valley due to increased volume of water from the captured river.

Examples of river capture in east Africa  include

• Lower Tiva captured upper Tiva river in eastern Kenya, formally a tributary of river Galana.
• River Aswa captured Agago, Moroto and Pager rivers in northern Uganda; reversed river- Rwizi, Katonga captured weaker adjacent rivers when Western Uganda uplifted.
• River Ruaha captured Pawaga drainage system in Tanzania.
• River Nile captured waters of river tochi, Okole and Arocha etc