Lab 11: Stream Processes and Landscapes

 

Objectives:

-          Stream Processes:

-          Drainage divides & basins

-          Trunk vs. tributary streams

-          3 channel types (straight, braided, meandering)

-          Stream gradient (should be review from topo lab)

-          Characteristics upstream vs. downstream

-          Alluvium

-          Delta vs. Alluvial fan

 

Introduction:

            Perennial streams: flow continuously during the year

            Intermittent streams: flow only during certain times of the year

            Flood: overflowing the banks of a stream or river

            Land erosion: wearing away of the land through stream processes

            Alluvium: sediment transported and deposited by streams and rivers, consists of gravel,

sand, + mud deposited in floodplains, point and channel bars, deltas and alluvial fans

 

Stream Processes and Landscapes:

            Sheetflow: sheets of water several millimeters or centimeters deep

            Figure 11.1 - Stream drainage system: sheetflows merge to form streams (headwaters,

tributaries), rivers (trunk), lakes and oceans

            Drainage patterns: characteristic patters of drainage, controlled by relief and geology

            Figure 11.2 - Dendritic, Rectangular, Radial, Centripetal, Annular, Trellis, Deranged

            Figure 11.1 - Drainage basin: entire area drained by one stream, or an entire stream

drainage system

            Divides: lines separating drainage basins (i.e. continental divide)

            Weathering: physically erodes and disintegrates or chemically decomposes or dissolves

Earth materials

            Transport and deposition: dependent on stream velocity and grain size

 

Valley Forms and Processes:

            Form and shape controlled by: geology, gradient, base level (lowest level to which a

stream can theoretically erode), discharge (rate of stream flow at a given time and location), load (amount of sediment that is transported)

            Figure 11.1 - Floodplains, meandering, cutbanks, point bar, oxbow lake, braided stream,

channel bars, stream terraces, delta, alluvial fan