Chapter11 - Chapter 11 River Systems and Landforms Chapter...

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Chapter 11 River Systems and Landforms Chapter 11 Reading Entire chapter but follow your notes Skip discharge formula on p. 350 Skip p. 367: streamflow measurement River Systems and Landforms Rivers transport the by-products of weathering, mass movement and erosion… …and deposit them elsewhere Rivers have tremendous energy – they comprise the dominant agent of landmass denudation Hydrology: science of water Fluvial Processes and Landscapes Fluvial – refers to stream-related processes Fluvial systems are natural systems with known processes that produce predictable landforms This does not mean that rivers are predictable! Insolation and gravity are the driving forces of fluvial systems Why insolation? Think hydrologic cycle. Erosion – surface material removed by wind, water, ice Streams erode sediment that is transported to new location, laid down in deposition process Stream is a mixture of water and solids Alluvium – clay, silt and sand transported by running water Base Level John Wesley Powell (1834-1902) Early director of USGS, explored Colorado River 1875, proposed idea of base level Level below which stream cannot erode its valley further Sea level is hypothetical ultimate base level Lowest practical level for all denudation processes Not every landscape will degrade to sea level Local base levels exist – control lower limit of local streams Can be river, lake, dam, or resistant rock structure Dynamic Equilibrium Endogenic processes build and create landscapes Exogenic ones lower landscapes and seek stability
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Streams modify landscapes through two basic processes: Erosive action of flowing water Deposition of materials transported by stream Drainage Basins Every stream has a drainage basin, the general area occupied by a river system and its tributaries Higher land (ridges) divide one stream from another Æ drainage divides Watershed = catchment area of the drainage basin After precipitation, water moves downslope in thin flow Æ overland flow or sheetflow Interfluves (high ground) separate one valley from another Surface runoff makes small grooves, rills , which make erode into deeper gullies over time Gullies may erode into larger valleys Drainage Divides U.S. has several continental divides , high drainage divides that mark the boundaries of flow to different parts of the continent Mountain and highland regions that send flows to Pacific, Gulf of Mexico, Atlantic, Hudson Bay, or Arctic Ocean Each major drainage basin made up of smaller basins These smaller basins deliver their precipitation and sediment to the larger basins Drainage Patterns Drainage pattern refers to how stream/river channels are arranged on the landscape Influenced by slope, rock resistance, relief of the land, climate Ohio River area near junction of West Virginia, Ohio and Kentucky Seven common drainage patterns
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This note was uploaded on 04/20/2008 for the course GEOS 200 taught by Professor Hanchette during the Spring '08 term at University of Louisville.

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Chapter11 - Chapter 11 River Systems and Landforms Chapter...

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