Chapter 14 Notes

Chapter 14 Notes - Chapter 14: River Systems and Landforms...

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Chapter 14: River Systems and Landforms Fluvial Processes and Landscapes Fluvial – stream related processes River – trunk stream or entire river system Stream – more general term not necessarily related to size Insolation and gravity power the hydrologic cycle and are driving forces of fluvial systems Erosion – water dislodges, dissolves, or removes surface material Fluvial erosion – produced by streams, process in which weathered sediment is picked up for transport to new locations Transport – movement of materials Deposition – materials re laid down Alluvium – general term for clay, silt, sand, gravel, or other unconsolidated rock and mineral fragments deposited by running water as sorted or semi sorted sediment on a floodplain, delta, or streambed Base Levels of Streams Base Level – level below which a stream cannot erode its valley Ultimate base level – sea level – average level between high and low tides Surface extending inland from sea level inclined gently upward under the continents, lowest level for all denudation processes Local Base Level – temporary base level that controls the lower limit of local streams o River, lake, hard and resistant rock, human made dam Landforms are produced by two basic processes: o Erosive action of flowing water o Deposition of stream transported materials Drainage Basins Every stream has one Ranges in size from tiny to vast Defined by ridges that form o drainage divides – the ridges are the dividing lines that control into which basin precipitation drains define a watershed – the catchment area of the drainage basin In any drainage basin, water initially moves downslope in thin film called sheet flow – over land flow Surface runoff concentrates in rills – small scale downhill grooves which my develop into deeper gullies and then into a stream course in the valley High ground that separates one valley from another and directs sheet flow is termed an interfluve Drainage Divides and Basins
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Continental Divides – high drainage divides, extensive mountain and highland regions that separate drainage basins Major drainage basin systems are made up of many smaller drainage basins o Each drainage basin gathers and delivers its precipitation and sediment to a larger basin, concentrating the volume into the main stream Drainage Density and Patterns Drainage Density – determined by dividing the total length of all stream channels in the basin by the area of the basin o The number and length of channels in a given area expresses the landscapes regional topography and surface appearance Drainage Pattern – arrangement of channels in an area o Determined by: Regional steepness
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This note was uploaded on 04/18/2008 for the course GEOG 101 taught by Professor Thebpanya during the Fall '07 term at Towson.

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Chapter 14 Notes - Chapter 14: River Systems and Landforms...

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