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WEAEXENING ZUNE JBO
<br />weathering zone-The top layer of the lithosphere in the katamorphic
<br />zone. extending from the surface of the ground to the groundwater table.
<br />In this belt, the physical and chemical processes are destructive, resulting
<br />in the breakin¢ down of the material of which it is composed. It is charac-
<br />terized by solutims. decrease in volume of ifs materiah and its wftening.
<br />L;elow the belt uF ~ceatherin¢ lies the belt of cementation. Also see aera-
<br />tion zone.
<br />weather map-A map showing the condition of the principal meteorologi-
<br />c:d elements at a given time. \leteorolo¢ical elements noted include the
<br />barometric pressure, the temperature. the state. of the weather, areas of
<br />precipitation, and wind conditions.
<br />1~'eber's number-A numerical quantity used as an index to charecterize
<br />the type of Flosv in a hydraulic structure where surface tension influences
<br />motion phenomena as a result of tension in the elastic skin, particularly
<br />~ien there is considerable curvature of this skin. in conjunction with the
<br />Istine force of inertia. It is eriual to: (u) the product of the square of a
<br />characteristic velocity of the system tit may be the mean, surface, or
<br />moximum velocity) and a characteristic linear dimension such as diame-
<br />ter or depth. divided by (G) the surface tension of the liquid; all expressed
<br />in coruistent units in order that the combinations will be dimensionless.
<br />The number is useful in certain studies of surface waves. Formation of
<br />drops and air bubbles, entrainment of air in Elovving water, and other
<br />related phenomena.
<br />weep hole-..An opening formed during the construction of retaining walls.
<br />aprons. canal.linin¢s. foundations. to permit drainage of water collectin_•
<br />Eebind and Serec::~ s:n_4 rc::cturs tr, ,-za :ce hydms:atic dead.
<br />weighted monthly mean precipitation-The weighted mean precipitation
<br />for each month for a laroe area. derived from the study of the isohyetal
<br />map of the area.
<br />weir-(1).{ diversion dam. (~).{ device that has a crest and some side con-
<br />ment of known geometric shape, suck as a 4', trapezoid, or rectan¢le.
<br />~is used to measure Flosv of liquid. The liquid surface is exposed to the
<br />atmosphere. f lose is related to upstream hei¢ht of water above the crest.
<br />to position of crest with respect to downstream seater surface, and to
<br />¢eometn~ of the weir opening. See weir flow formulas.
<br />weir-See following terms modif<~ing w~eir~. broad-crested. Cipolletti, con-
<br />tracted. crib. di~ertin¢. drovyned. effluent, flal•crested, free. frictiun•
<br />influent, irregular, leaping, log, movable. needle, notched. overfall•
<br />oyer(lovv, parabolic. peripheral, proportional. rectangular. rollin,•uP
<br />curtain. rounded-crest. separating. sliarp•crested, shutter, side•flu<''•
<br />skimming. sliding-panel, submerged. suppressed, suspendcd•fram<••
<br />Sutro. trapezoidal, triangular. 6-notch. waste, wide-crested.
<br />7!r WELt ita001NG
<br />weir box-.{ box installed in a nan-n<v open channel upstream fmin a weir to
<br />provide an enlargement of the svatenvay, wherein the velocity of
<br />approach to the weir will be reduced.
<br />weir loading-In a solids-contact ur sedimentation unit, the rate in ealluns
<br />per minute per font of weir length at which clarified or treated liquid is
<br />leaving the unit..{Iso see overflow rate.
<br />weir loading-In asolids-contact unit, the rate in gallons per minute per
<br />foot of weir length at which clarified or treated liquid is leasing the unit.
<br />Also see overflow rate. -
<br />welded steel pipe-Steel pipe made from sheets of steel curved int.!
<br />cylindrical shape with the edges welded together. Field joints may he
<br />flanged, screwed, or welded. The seams may form a spiral cloning
<br />around the circumference of the pipe with welding along the seam.
<br />well-(1) An artificial excavation that derives seater from the interstices of
<br />the racks or soil which it penetrates. (2) ,{ shaft or hole into which water
<br />may be conducted by ditches to drain other portions of a piece of work.
<br />well(s)-See following terms modifying well(s): absorbin¢. abyssinian.
<br />artesian, artesian flowing, battery of, blowing, bored, breathing, clear,
<br />combination, confined-water. dead, diffusing, drain, drainage. drilled,
<br />driven, dry, dug, entrance, flowing, gang oF, gravel-wall. horizontal.
<br />inlet, inverted, inverted drainage. Maui-type, natural. natural strainer,
<br />negative, nonartesian, nonflowing, open, open-bottomed, open-ended.
<br />perforated-casin¢, pump. push, radial, recha:_e, screened. ::il:-;.
<br />strainer, subartesian. tubular, water, svater•table, wet.
<br />well capacity-The maximum rate at svlEich a well will yield state: under a
<br />stipulated set of conditions such as a given drasydnsvn, pump anti motor,
<br />or engine size. ft may be expressed in terms of gallons per minute, cubic
<br />feet per second, or other similar units.
<br />well casing-Metal pipe used to line the borehole of a well.
<br />well cone of influence-The depression, roughly conical in shaor. pr!!-
<br />duced in a water table or other piezometric surface by the cyt.•lcti,m „f
<br />water From a well at a given rate. The volume of the amt w ill ~ an ss ith
<br />the rate and duration of withdrawal of ss titer. {Iso called i~nl,• .d
<br />depression.
<br />well curb-A concrete or masunn parapet built around a ssrll ~r tmllnd
<br />level to prevent drainage of surface water into the sell.
<br />well field-.{ tract of land containing a number of wells.
<br />well flooding-(I) A process of divertin¢ .eater from streams when the
<br />supph~ exceeds the demand and allowing it to pass into the <atllrallnll
<br />zone through a well rnnstructed Fnr the purpose. See Good spreading,
<br />spreading. (3) The overtopping o(a syell by Flood syatcrs.
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