Laserfiche WebLink
<br />-"""__"--ll'L cR' ,', 8fh" . ._ ._, ~ , <br />~~...:;;:':~~:~.r-.:r:.:r:>~"",__...13'-' =a... _ _"",,, <br />(j ...3!J <br /> <br />.'" ..~ u-d:"....l. __ '~+'-~"'--=-~P;B5 t <br /> <br />'.,-:, <br /> <br />that cottonwood Illaintenance flows are about three to four tiees gr'eater than <br />the averas,e annllal dlver'ted flows, and aoout. forty to sixty percent of the <br />estimated annual natural flow. 1 <br /> <br />The .'3ea3onality of growth can change a.:3 a result. of diversion flows. For <br />example, the Rush Creek diversion creates an artificial hydJ'ograph peak in <br />July, as opposed to the prediverslon peak In June (the d!verslon peak is twenty <br />percent of the prediversion peak). As a consequence the main growth period for <br />black cottonwood shifted from May -- predlverslon, to July/August __ diversion <br />(Stronberg and Patte~l 1990). The annual diameter Incr'e~ent also deCreaS(!5 as a <br />result of the poereI' growth conditions (temperature, relative hU::lidit.y, soil <br />noi.!ture to name a few) that OCcur during the later "growing season." <br /> <br />StroDberg and Patten (1991) determined that the presence of cottonwood cannot <br />be interpreted as an indicator of sufficient flous. The flows necessary to <br />ensure cottonwood recruitment are different than those which rr.alntain ekistlng <br />cottonwood stands -- both in Quantity and in timing. In general, maintenance <br />flows are less than ~ecruitnent flows, so even if the current cottonwood stands <br />persist regeneratien will not occur if maintenance is the only objective. They <br />also concluded that growth and flow relationships can a1d in determining <br />riparian based streamflow requlrement.~, presuming that plant individual and <br />community maintenance is dependent on certain levels of growth rates (Stfombcrg <br />and Pattan 1990). <br /> <br />Sweden <br /> <br />Host riparian habitat in SHed en has been affected by streamflow regulation. <br />The effect has been th~ complete de3truction ~f riparian habitat, although some <br />individual species h,nve adapted to r:e... environ..,ents. But even :lIore <br />significant, peak :""-Io-off 1n unregulated str-ea::lS of ncrthern S....eden occurs <br />during 'now~elt in th~ springtine. The seasonal ~loodlr.g maintains the <br /> <br />------ ----~~. ----- <br /> <br />lTtJ~ :'e;:J.d~r is -.:..1o.ltL:wp.<.1 t:. fC,X'gl,:?r: tnat l:'.j-,o;:::~ ~1tt!-$pecific CC:1clusions <br />a:'p. tJas"'d Ol~ ;:O:'C'11,.;-'~(1 1.,'l1<. ~tj:":.1:": oni-v arc ::~ rlot reflect ~<.!nterlance <br />re'1.Ji:"e."'€:1~s ;'J!' 1..~r.-:::O! L'''":\.I'.::....1 SPE-\:.i-;"s. ~..:ch as "U10\.l, alder, ::"aple, forbs, <br />gr:!$.s€s, S.;dgASI ..:J: -. e.~. <br />