Earth Sciences 1022A/B Lecture Notes - Lecture 15: Abrasive Blasting, Mass Wasting, Bed Load
10 Jan 2017
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Document Summary
Hydrologic cycle 97% of earths water is stored in the oceans, evaporated then precipitated on land. Some flows over the land as streams (runoff) Some evaporates back into the atmosphere and is transpired by plants. However, most returns to the oceans by streams. Stream flow stream erodes, transports according to its velocity and channel shape. Gradient slope of stream channel over its length. Cross sectional shape determines how much of the channel contracts water, slowing it down. Discharge volume of water flowing through the stream"s cross sectional per second. If discharge increase, stream usually gets wider, deeper, and faster downstream. Streams erode, transport, and deposit simultaneously over their lengths. Erosion by abstraction using particles in transport as cutting tools to scour channel walls (like sandblasting) and in circular eddies to cut potholes into the channel floor. Deposition occurs when stream can no longer carry its load and particles fall to the bed.
