Drainage Basins Watersheds

What is a watershed? The area of land drained by any one stream Includes the main river and all of its tributaries

What is a tributary? A smaller stream that flows into a larger one

Tributaries As water continues to flow through tributaries, it combines with more water. So the size of the stream gets bigger and bigger A B

What happens to water when it hits the ground?

What causes water to flow? Hint: Underlying force behind all erosion! GRAVITY So that means water always flows from high elevation to low elevation

What do the bold lines represent?

… divides between drainage basins

Label! Ontario Susquehanna Mohawk St. Lawrence Champlain Long Island Sound Allegheny Erie

4 of the watersheds feed into the St 4 of the watersheds feed into the St. Lawrence River, then into the Atlantic Ocean A. Ontario D. St. Lawrence E. Champlain I. Erie

Where do the others go? B. Susquehanna – Chesapeake Bay F. Long Island Sound – Atlantic Ocean C. Mohawk- Hudson River G. Delaware – Delaware River H. Allegheny – Ohio River

Susquehanna – Chesapeake Bay

Long Island Sound – Atlantic Ocean

Mohawk- Hudson River

Delaware – Delaware River

Allegheny – Ohio River

Watersheds fit together like puzzle pieces

Continental Divide The United States is split into two large drainage basins

Mountains Topography, like mountains, determines which watershed the rain will enter.

Drainage Patterns Dendritic Radial Rectangular Trellis

Dendritic Most common Looks like tree roots It develops in regions underlain by homogeneous material (consisting of parts of the same kind) The bedrock all has a similar resistance to weathering so there is not a path of least resistance the resistance is equal in every direction

Dendritic

Radial Develops around a central elevated point The pattern is commonly found on cone shaped features (Volcanoes) Tributary streams start at the highest point (top of the volcano)

Radial

Rectangular Found in regions that have undergone faulting Streams follow the path of least resistance Faulting causes movement of the surface Off-sets the direction of the stream Tributary streams make sharp bends

Rectangular

Trellis Looks like a garden trellis Develops in folded topography Down-turned folds called synclines form valleys in which the main channel of the stream flows Short tributary streams enter the main channel at sharp angles As the tributaries run down sides of parallel ridges

Trellis