GEOG 1010 Lecture 15: Lecture15
Document Summary
If there is excess power in a stream, then it may erode more materials from the stream bed or bank. If stream power is insufficient, then deposition occurs until load matches power. A stream must lose power to move sediment when it switches from erosion to deposition. Stream power is the result of shear stress and velocity. Loss of discharge will cause deposition, because without water there is no shear stress, nor any velocity. Deposition happens where water depth decreases and stream power drops off. A stream in arid landscapes where depth goes to zero very rapidly (like when a stream empties out onto a valley floor), results in alluvial fans. Alluvial fans: forms where the stream goes from confined to unconfined. Deposition occurs where velocity decreases, since power is a function of velocity. When a river enters a quieter body of water (ocean, sea, lake), the drop in velocity causes deposition of its sediment load.
