<br />.
<br />
<br />.
<br />
<br />.
<br />
<br />001953
<br />
<br />the end of the period of record (1994) were much less than the withdrawals made in the late 1970's and
<br />
<br />early 1980's.
<br />
<br />Channel Processes
<br />
<br />As stated previously, the Arkansas River and the surrounding alluvial aquifer can exchange water.
<br />
<br />When the river is recharging the aquifer, the amount of recharge increases as theJeFI of the river
<br />,-' "~
<br />
<br />increases. In the short term, increases in river level, or stage, are related to )h~~~'h;:~at~"s,~A!Q~. For
<br />
<br />instance, flow typically increases when there are widespread rains. In t,e-l~;~~'I.J'lF~~~~)h:1evel
<br />'\ v JF"j J","" ,I
<br />of the river may change due increases in the elevation of the rivet€~),,'.\) <~~;~~~::':/
<br />",,,,,,~'-, (~/, i 'c-.-/r-,,_ \'~j
<br />Watts and others (1992) documented a general incre,\~e'~fCt~~i~v,a~~n~y2fb:Vriver bed for the
<br />
<br />Arkansas River at La Junta by evaluating the eIevation(~ th~~~~~t;~~~,~hiCh is determined
<br /><'::,',""',:l \ (' ,(/7) ,,) .J
<br />routinely as a part of maintaining streamflow re.c6~~sl:in"tb)s ,st1i~tao~inJilar method was used to eva1-
<br />:< -<'/>',,,"'''::' ((/ ,~,,~<>/
<br />uate changes in river-bed elevation. Co" >1>' ~: ""'.' """'~, v'
<br />,'>, \\ ;'~'M/ /', '''''' "",
<br />The method used in this studY'lo!i1~~~r~f..,k~ot~~ the specific-stage method (Simon, 1994),
<br />/"" ,,\:" "~~",,;' ,/ <, ^'o~"^,,,-,/'
<br />tracks the river elevation for a s~~ill'i~~scha~e~tTse,ofthis method can return more frequent values
<br />A " 'h. '\." 4' """ ""
<br />// "~.".,\>- '~" ">"" ,;/ /
<br />and also provides an anaIysi~~lf~d,pn l(l;R;l~s\section of the river rather than a single point in the cross
<br />"'\ ~\\'\:. '~,> 1/';::;' . "'\'\>
<br />section. Even thougp~he.)n~tH~ Jtldf"be ~~!,ed on a cross section rather than a point, it stilI describes
<br /><"' <>---~> ;'::;,// j/>~~!-~"~-~--:>/
<br />the river bed onIY'1\ttHa(cfo,ss~ecti6n)nd cannot be applied to a river reach without additional
<br />/ .', " '\,- - \, '''"' 'y /
<br /><" <.,'.- -,' "'," ~"- '\--~ /
<br />- ~,,' ~-" '1 ~/
<br />supporting/.iii:r/l;rm', 'illtio\l(', ,"'
<br />'{ '">:,,
<br />:,,// '// ,/,: i
<br />The \'esult~Qfth.lii~Qa'i~sis are listed in table 4 and shown in figure 7. The results indicate that the
<br />,
<br />, -', ~
<br />elevation of {h.e.'fiyerhed has generally increased steadily throughout the study period. The changes in
<br />, ' ," ,
<br />" / "
<br />
<br />river bed elevations, unlike the changes in most of the factors previously discussed in this section, are
<br />
<br />relatively steady.The total increase, from 1960 to 1996, is about 1.75 feet. Between 1996 and 1997 the
<br />
<br />records indicated an increase of almost 1 foot which is a much greater increase than has occurred histor-
<br />
<br />ically and may be a short-term phenomenon.
<br />
<br />15
<br />
|