Reference work entry
Synonym: Diverter, capturing river
A pirate river is also known as a capturing river. During the process of watershed regression by rivers on both sides of a water divide, the stream with the stronger headward erosional power cuts back into the divide and captures the neighbouring river. The stronger river is called a capturing river. At the point where river-capture takes place, there is usually a marked bend, known as the elbow of capture. The riverbed of the capturing river is lower than that of the captured river, and the marked difference in water level helps to facilitate the formation of cascades. The capturing river will gradually grow and increase in water volume, resulting in strengthening of its erosional power. The cascade continues to recede towards the captured river and cuts down to the riverbed to form fluvial terraces or a valley-in-valley landscape (Fig. 20).
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