Chapter 13 Surface Water

Streams and Rivers Words to remember: Tributary Watershed River System Divide Discharge Gradient Velocity Distributary Exotic Stream

Streams and Rivers Half of the water that falls to earth ends up in a river or stream Rain can run down and run into a large stream. A stream that runs into another stream is called a Tributary A stream that branches off from a main stream is called a Distributary.

A river system is the river and all of its tributaries. Water can carry sediment or bits of eroded rock. The drainage basin (watershed)- includes all of the land that drains into the river either directly or through a tributary.

The high land that separates a drainage basin is called a divide.

River Mouth- (end) is an opening in a river that usually flows into another river. River Source- (start) farthest point away from the estuary where the river gets supplied water. Estuary- enclosed area where streams meet and flow out into the sea.

Characteristics of Rivers or Streams Velocity- the distance that water travels in a given time Gradient- the steepness of the stream or river. Discharge- the amount of water that passes through a certain point in a given amount of time. Channel – the path through which the water flows in a stream or river.

Exotic Stream An exotic Stream is a river that crosses through a desert before making its way out to sea.

Erosion and Deposition Running water is the most effective of all agents of erosion Erosion is the weathering away of rock by either water, wind, etc. Deposition is the process where materials are deposited after a stream has no more energy to carry them.

How water carries rocks A river can erode away at rock and carry it downstream. The rock and soil materials being transported are referred to as a load. The most common method is through suspension.

How water carries rocks Suspension is when rock materials are stirred up and kept from sinking by turbulence of the streams flow. Sediment can also be carried in a bed load which is when a river transports rock materials too heavy to be carried in a suspension such as sand, pebbles, and boulders. And in a solution where mineral matter has been dissolved from bedrock.

Loads:

It Creates Landforms Fluvial- refer to the processes associated with rivers and streams and the deposits and landforms created by them Most Common: Delta- fan shaped deposit that forms when a river flows into a quiet or large body of water. Alluvial Fan- forms when a steep mountain stream meets dry, level land at the bottom of the mountain.

V- Shaped Valley Most young rivers are made into V-shaped Valleys because of surface water eroding away as it runs down into the river.

Floodplains and Floods Floodplains are the part of the valley that is covered with water during a flood. A river flowing through a floodplain usually flows back and forth in broad curves called Meanders.

Meanders often can change. Sometimes after the water drops, silt and mud are deposited at the ends of an old meander, trapping water. This curved body of water that is separated from its meander is called a Oxbow Lake.

A flood can bring a lot of sediment into a given area. As the flow of the river slows down after the flood, so does the sediment. As it starts to slow down, it begins depositing on the sides of the stream forming natural levees.

Floodplain