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.