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River and Stream Erosion. Complete Starter. Hydrologic Cycle. Water’s trip . Water picks up energy as it flows downhill. Water that does not soak into the ground or evaporate will runoff. Runoff eventually empties into streams, lakes or oceans. What Affects Runoff? .
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Water’s trip • Water picks up energy as it flows downhill. • Water that does not soak into the ground or evaporate will runoff. • Runoff eventually empties into streams, lakes or oceans.
What Affects Runoff? • Amount of rain that falls • Amount of vegetation on the land • Time span over which it falls • Slope (steepness) of land
Stream Erosion • Forms deep and wide channels carrying many sizes of sediment.
How are Streams Classified? • Classified by their ages • Ages can be identified by: • Landforms • Velocity (speed) of the water • Carrying ability (size of the sediment it can transport)
Young or Youth Streams/River • Fast flow • Steep V-shape • Large boulders are moved
Mature Streams • Flow slower • Starting to meander • Does not carry boulders, large rocks bounce on the bottom of streams meander
Old Streams • Flow slowly through wide, flat floodplains. • Smallest sediments • Suspended load – sediments are in the column of water • Dissolved load – dissolved sediment Features include: Oxbow lakes, large meanders
Parts of a River System • A stream that runs into another stream or river is called a tributary. • The running water carries bits of eroded rock called sediment. Larger tributaries carry this sediment until it reaches a main river. The main river carries the sediment to a lake or an ocean and deposits it there. • A river and all of its tributaries is called a river system.
Parts of a River System • The drainage basin, or watershed, of a river includes all the land that drains into the river either directly or through its tributaries. The high land that separates one drainage basin from another is called a divide. • Example: N. American Continental Divide.
Characteristics of River Erosion Velocity • The distancethat water travels in a given amount of time. The velocity of the water in a river is related to the amount of energy that the water has. Factors: • steepness of the slope, • the amount of water • shape of the path. A fast-moving river erodes more quickly/carry larger particles
Characteristics of a River Gradient • Is the steepness of the slope of a stream or river .. A river’s gradient varies along its course.
Characteristics of a River Discharge • The discharge of a stream or river is the amount, or volume, of water that passes a certain point in a given amount of time. • In many rivers, discharge increases downstream because tributaries continually add more water.
Characteristics of a River Channel • The path through which the water flows in a stream or river. • The size and shape of a channel affect the velocity of water.