by Maddie, Ty, McKinley, and Garrett Stream Erosion by Maddie, Ty, McKinley, and Garrett

Parts of a River System

Tributaries: all of the feeder streams that flow into the mainstream Watershed: the land from which water runs off into streams Divides: ridges/elevated regions that separate watersheds Channel: narrow depression that a stream follows as it flows downhill

Channel Erosion

Headward Erosion: in this process channels lengthen and branch out where the runoff enters the stream Stream Piracy: a stream from one watershed is captured by a stream from another watershed that has a higher rate of erosion the captured system drains back into the river that it stole from

Stream Load: the materials carried by a stream suspended load (fine sand and silt) bed load (coarse sand, gravel, and pebbles) dissolved load (mineral matter transported in liquid solutions)

Stream Discharge: the volume of water moved by a stream in a given time period The faster the stream flows, the higher the discharge and greater load it can carry. Swift streams erode dirt channels more quickly than slow-moving streams do.

Stream Gradient : change in elevation of a stream over a given horizontal distance steepness generally steepest at headwaters, flatter at mouth

Development of River CHannels

Meandering Channels A developing river may for curves and bends Meanders: winding pattern of wide curves more bends with low gradients causes erosions of banks, forms a bar of deposited sediment on the curve Oxbow Lake: forms when meanders curve so much they form a loop and become isolated from the river

Oxbow Lake

Braided Streams Braided stream: stream or river made of multiple channels that divide, rejoin around sediment bars result of high gradient, large sediment load cause as much erosion as meandering channel

List at least three parts of a river system. Questions List at least three parts of a river system. What are the three types of stream load? How does stream discharge and gradient affect the erosive ability of a river?