Earth & Space Science

Unit 12: Rivers & GroundwaterPPT #1

Chapter 5 Opening FigureChapter 13

Rivers and Streams

Mississippi River drainage system The largest

river system in the U.S! (watershed)

mouth

headwaters

TRIBUTARY:A river that flows into another (larger) river

Watershed

• Also called a drainage basin• Consists of a river and all of its tributaries

(a stream or river that flows into another river)

• Drains the rainfall from the land.

What % of the U.S. is drained by the Mississippi River watershed?

http://www.youtube.com/watch?v=ofTdglXriug

The Mississippi River Drainage Basin or Watershed

• drains 41% of continental United States. • Drains 31 states and 2 Canadian provinces• The total area is 1.2 - 1.8 million sq. mi2.• River length is about 2,300 miles (3,705 km)

A raindrop falling into Lake Itasca would arrive at the Gulf of Mexico in about 90 days!

• Water flows to its lowest elevation, where it forms a river or stream.

• The lowest possible elevation is sea level (the ocean)

• The elevation of the Mississippi at Lake Itasca is 1,475 ft above sea level.

• It drops to 0 feet above sea level in Louisiana at the Gulf of Mexico.

Due to gravity, water always flows from higher elevation to lower elevation (downhill)

Sea level 0 feet

Where are the the continental divides?

Rocky Mountains:Western continental divide

Appalachian Mountains:Eastern continental divide

Nevada’s rivers sit in a low basin surrounded by mountains.The rivers are unable to drain / flow out

Erie Canal• Opened in 1825, the Erie Canal was the engineering marvel of the

19th Century. It cost $7 million for construction of the Canal • The canal is 363 miles long, 40 feet wide and 4 feet deep.

• The Erie Canal spurred the first great westward movement of American settlers, gave access to the rich land and resources west of the Appalachians. The effect of the Canal was immediate and dramatic and settlers poured west.

• It made New York the dominant commercial city in the United States. New York was the busiest port in America explosion of trade within 15 years of the

Canal's opening,

• The Canal connected Buffalo, N.Y. on the eastern shore of Lake Erie to Albany, N.Y. on the upper Hudson River, a distance of almost 400 miles.

X

Eerie Cnal

St. Lawrence River

Sea level 0 ft.

St. Lawrence River flows to a lower elevation – sea level (the Atlantic Ocean)

Illinois River watersheds

The glaciers determined the location of the rivers

Does the Nile River flow UP?

No, it’s impossible for water to flow UPHILL!

The mouth of the Nile River

is at sea level elevation = 0 meters

Aswan, Egypt:550 meters above sea

level

So…

The Nile River, like all river flows downhill, from higher elevation to lower elevation, which happens to be north

N

Main Points

• Water returns to Earth in the form of precipitation, this includes rain and snow.

• This water collects in rivers, streams, and lakes and eventually will more to the lowest point.

• Rivers flow from the highest point to the lowest point. Depending on the gradient (slope) of the land this can be in any direction (North, South, East, or West)