Viscosity or internal friction is the property of a

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Unformatted text preview: r internal friction, is the property of a substance, a water/sediment mixture when applied to fluvial systems, to resist flow; viscosity is measured as the coefficient of viscosity, the ratio of shear-stress rate to the shear-strain rate. W Wadi is a channel, generally in arid or semiarid areas of southwestern Asia, the Arabian Peninsula, and northern Africa, in which streamflow occurs inconsistently or infrequently and, except during periods of streamflow, is directly underlain by unsaturated alluvium; wadis typically have a rectangular to steeply sided trapezoidal cross section, banks a meter or more in height formed of fine-grained, poorly consolidated over-bank sediment, and a nearly flat, sandy bed. Synonyms are ephemeral-stream channel, dry wash, and arroyo (northern Mexico and southwestern United States). Wash load is the part of the total sediment load of a stream that is usually supplied from bank erosion or from upland sources by overland flow. It is the finest part of the load (that part which typically can be held in suspension at even very low stream velocity) that can be easily carried in large quantities (it is “supply-limited”, not “transport-limited”); it is generally determined by assuming that suspended sediment in transport that is finer than 0.062 mm is the wash load. Water balance is an accounting of the volumes of water entering, leaving, and stored in a hydrologic area or unit, typically a drainage basin or aquifer, during a specified time period in which the amount of water entering the area or unit equals the amount leaving; in equation form, the water balance, or hydrologic budget, for a drainage basin is expressed as P = O + ET – I + ΔS, in which P is precipitation, O is outflow, as streamflow, ET is water lost through evapotranspiration and sublimation (including loss of intercepted precipitation), I is inflow, as streamflow and runon, and ΔS is change in stored water, including ground water, soil moisture, and imposed additions or extractions. Watershed is a drainage divide or a “water parting”, but commonly usage of the term has been altered to signify a drainage-basin area contributing water to a network of stream channels, a lake, or other topographic lows where water can collect. 47 Watershed management is, through the application of scientific principles and knowledge of drainage-basin characteristics, the administration and regulation of water and related natural resources of land, soil, and biota of the watershed for the beneficial use and conservation of those resources; included are the management of water and plant resources and the control of fluvial processes (especially erosion and sediment deposition). Water table is a lay term to describe the surface defined by the top of the zone of saturation in a non-confined, often alluvial, aquifer. Water year is the period October 1 through September 30; in most mid-latitude areas of the northern hemisphere, the general time of October 1 is one of low flow, hence the selection of October 1 as break date. Weathering is the destruction or alteration, through chemical and biochemical processes, of near-surface rock and sediment; weathering leads to the removal of waste products as dissolved loads in water but results in little or no transport of solids (erosion) that are released or modified by the weathering process. Wetland is a bottomland or low-lying area, including ephemeral-lake floors, at which water either is shallowly ponded on the surface or has a persistent (weeks or longer) near-surface condition of ground-water saturation adequate to support hydrophytic vegetation. Wetted perimeter of a channel section is the length of which water is in contact with the channel bed and banks; wetted perimeter is a hydraulic parameter in the computation of streamflow from physical properties of the channel. Winnowing is the preferential entrainment and transport of fine particles from those of the coarse fraction of a sediment deposit by fluid motion; the term is applied especially to the transport of fine sediment sizes from a poorly sorted reservoir of sediment by wind, but the winnowing process occurs also by the action of water moving on hillslopes, in rills and gullies, in stream channels, and along beaches and other parts of lakes or oceanic tidal zones. X Xeric refers to an environment (habitat) that is characterized by deficient moisture. Xerophyte is a plant that is adapted to a habitat of low moisture availability. Y Yardang is a sharp-crested landform, of relatively soft, generally fine-grained sedimentary or volcanic rocks, that is typically oriented parallel to the dominant wind direction an arid region or desert and has surfaces sculpted by processes of abrasion by wind-entrained sediment (mostly sand and silt). 48 Z Zone of aeration, or zone of vadose water, is the typically moist but unsaturated subsurface zone between the land surface and the top of the zone of saturation (water table). Zone of saturation is that part of the subsurface in which the interstices of porous and permeable rocks are saturated with water under pressure equal to or greater than atmospheric pressure. Major sources of information: ASTM Subcommittee D19.07, 1999, D4410-98, Terminology for fluvial sediment: American Society for Testing and Materials, West Conshohocken, PA, USA, 6 p. Fairbridge, R. W. (ed.), 1968, The Encyclopedia of Geomorphology: Reinhold Book Corp., New York, 1296 p. Goudie, Andrew (ed.), 1994, The Encyclopedic Dictionary of Physical Geography: Blackwell Publishing, Oxford, UK, 544 p. Goudie, Andrew (ed.), 2003, The Encyclopedia of Geomorphology: Routledge, London, UK, 1200 p. Interagency Advisory Committee on Water Data, 1982, Flood Flow Frequency: Bulletin 17B, Hydrology Subcommittee, U. S. Geological Survey, Reston, VA, USA, 28 p. Langbein, W. B., and Iseri, K. T., 1960, General introduction and hydrologic definitions: U. S. Geological Survey Water-Supply Paper 1541-A, 21 p. MacArthur, R. C., and Hall, B. R., 2008, Appendix E, Limited Glossary of Selected Terms, In García, M. H. (ed.), Sedimentation Engineering: American Society of Civil Engineers Manuals and Reports on Engineering Practice no. 110, 1132 p. Monkhouse, F. J., and Small, John, 1978, A Dictionary of the Natural Environment: John Wiley & Sons, New York, 320 p. Neuendorf, Klaus K. E., Mehl, J. P., and Jackson, J. A. (eds.), 2005, Glossary of Geology, 5th Edition: American Geological Institute, Alexandria, VA, USA, 779 p. Phreatophyte Subcommittee PSIAC, 1962, Glossary of terms relating to the phreatophyte problem: Pacific Southwest Inter-Agency Committee, Menlo Park, CA, USA, 7p. Schumm, S. A., 1977, The Fluvial System: John Wiley and Sons, New York. U. S. Geological Survey, 2007, Glossary of the National Water-Quality Assessment (NAWQA) Program: NAWQA,, 19 p.. 49...
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This document was uploaded on 02/26/2014 for the course ES 322 at Western Oregon University.

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