SMALL WATERSHEDS / DRAINAGE BASINS Def: The area of land drained by any one stream REMEMBER: a stream is running water that’s confined to a channel---this channel can be any size: LARGE MEDIUM

Q:Where does water go once it hits the surface of the earth? A: Some gets absorbed into the ground (infiltration) some flows along the surface (runoff)

Water always flows from HIGH elevation to LOW elevation. Along the way, this water combines with other water, so the size of the stream gets bigger and bigger. A B The smaller streams are called tributaries.

The rivers of New York State obtain their water from very distinct regions. The state is divided into the following DRAINAGE BASINS (WATERSHEDS): In what drainage basin is Hyde Park? These watershed regions are pretty small because the streams they feed into are pretty small

Watersheds: Continental Divide and Appalachian Mountains Water goes from high sea level to low sea level

The UNITED STATES is split into two LARGE drainage basins. This side, all water flows to PACIFIC OCEAN This side, all water flows to ATLANTIC OCEAN

Drainage Patterns of Watersheds –Dendritic –Radial –Rectangular –Trellis

Dendritic Drainage Patterns Dendritic drainage pattern is the most common form and looks like the branching pattern of tree roots. It develops in regions underlain by homogeneous material. The subsurface bedrock all has a similar resistance to weathering so there is not a path of least resistance, the resistance is equal in every direction the tributaries take. Tributaries joining larger streams at acute angle (less than 90 degrees).

Drainage Patterns of Watersheds –Dendritic –Radial –Rectangular –Trellis

Radial Drainage Patterns radial drainage pattern develops around a central elevated point. This pattern is common to cone shaped features such as volcanoes. The tributary streams originate at the highest points toward the top of the volcano or cone.

Drainage Patterns of Watersheds –Dendritic –Radial –Rectangular –Trellis

Rectangular Drainage Patterns rectangular drainage pattern is found in regions that have undergone faulting. Streams follow the path of least resistance and thus are concentrated in places where exposed rock is the weakest. Movement of the surface due to faulting off-sets the direction of the stream. As a result, the tributary streams make sharp bends and enter the main stream at high angles.

Drainage Patterns of Watersheds –Dendritic –Radial –Rectangular –Trellis

Trellis Drainage Patterns Trellis drainage patterns look similar to their namesake, the common garden trellis. Trellis drainage develops in folded topography like that found in the Appalachian Mountains of North America. 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 called anticlines. Tributaries join the main stream at nearly right angles.