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<br />it-s <br />3. Adjust the average temperatures to the average watershed <br />elevation, using the method given below in 4diustaent of <br />-°=nerat~^es for altitude. This sten ie omitted when elevation <br />data are crude or atheruise unreliable. <br />4. Conpute the watershed average daily temperatures by averaging <br />the station averages (adjusted for altitude, if desirable). <br />5. Subtract 32° F. from each watershed average daily temperature <br />to get the deeree~eys per dap. <br />6. Use ecuatio: _~-1 to get an estimate of the potential enovmelt <br />for each dap. See K factors below for selection of K. <br />7. Where the daily potential is not greater than the eater <br />equivalent remaining on the watershed, it ie shcvn as an <br />satinets of snowmelt. <br />~-~::~ <br />.'1~ <br />„~•..~ . <br />:~ <br />_'~1 <br />.~: •,: <br />.. ~ :;;: <br />-~'.M1J <br />-~'a'~' <br />~, :fir. <br />Once :he estimates of snoumelt are obtaihed, they .are used to obtain <br />l~drographs as described in Chanter 16. <br />Soae hydrolcgists suggest that the effects of infiltration be subtracted <br />from the estimated snovmeit. However, the K fsawrs as eenerally <br />develoeed already include the effects of infiltration. 'Phe effects of <br />measures such as contour furrows era ootainea as aescribea in Ohaoter 12. <br />The effects o: reservoirs, levees, etc. era ootainea as usual. <br />?.ef~;ents in the aegrea-nay metnoa are nest mane oy first isproving <br />:he accuracy o! cetercanaLions of snow aeptn and areal aisLr~bution on <br />~_e •aet=_rsnea. »nea these are :~:ovn :.zti.a scan 1_i.a o: error, cnen <br />rater equivalaats snouici ~a racinen, Since the ~/10 ratio is a roman <br />r_ror_.:stion. :~efiremerts ~r. .~ ._otors snou;.d _ome ins t. <br />Cea^e=-riav method. ~aKed •:atersned <br />The degrae~ay method has a vary ?-±ted use, :_ .:-yr at ~_, fo.- hood <br />BV81118ti0IIS 0II gaged :latersfled5. .~Ge] ~8~1:~ ~tBLiOn GatB Era 848j.18b18, <br />those asta should be USdi t0 d5ti-aLa i1:CG ~tlad9 z.c :oi.~.es cll .;LaBr <br />portions of the watershed. <br />Adjustment O_' ~ - ai,_743 ' _•9 <br />In general, air temperatures decrease about 3° to 5" __r ever,/ i,.:.0 <br />Seet of se in altitude. Cther factors i~`luence -ms's "lsnse rated"^ <br />so that refire=ants are not °nst'_fied, '^^ as svorega docreeae o: ~ _. <br />per 1,000 feet rise s!:ould be used. <br />:.--s <br />_ ... .:_Y <br />