up |a a lew rnelres muss wuuld he (nmplflzly covered
wuh .1 wuuden ham: severed wllh thck 5})!ka lhus
pmvldmg bum made and mud pmleenun, (mud
lanlss are lrkewrse pnneered hum wlnd losses. allhuugh
Vapour Pressure all («use surne [055 m unshaded
ranks Rouled eurrh unks nre snll wrdely used .n
Ausrralra

lur mare exrensree waler sysrems, skvalegics have
rsnged lrurn Iluilmg ralrs or wax, ld lhe more
pennanenl am elleerwe srnnegy used .n Sourh Alnea.
where hrxaganal llonrs nl whllc surlaeed ‘llghl‘
euneeele (a slurry ol eernenl, sand, .ne gravel and
polyslyrene beadsl ure lluared ou| unlll rhe ennre
salelnnenl surlaee ls eneered Thls .s very elleelwe
where waler 15 ran' nr enpensne Lnrger and lrghrer
rdhs euuld be nude 0! wzled prpe llnars and rhrn
panels, bul rhe eunerere rs durable und su-nple, block
are rar—senled beluw, and rhenspeelln gravxry Is as. so
lhal rhey llnar deep enough In resrsl wave ellesl.
Corners are munded m illnw an l0 lhe waler,

STRUCTURE OF DAMS
There are elk-(UV: apprnaenes |u rhe s|nl<l||ul
elleeuvenessnl dams The “N l, le makc lhe darn .sell
as a deep enunnl seennn, ,0 mar as lhe level lalls.
sumee nren rs AM vapldly .edueed (a~ lhe square 0) lhe
rnurusl Muth nl lhv name elleel rs aehreved m
'v shaped valll'y sledge-s,

Semndly, deep and shaded \ulllev sues elm lar beller
pruleeled [mm sun and wlnd lhan shallow alleys. and
ll elun us pusslbl: a shndsd easlrwvsl valley .s lusr

Thlldly, a ~lmp|r Mmmxy ul malmg s sencs or 3A
slurnees, each able le be drarned by gmvlly flaw |<\ rhe
NM lnu r darn rs vrrv elleeuue llnr more so luau n

slngle slorage ul rhe same lurlsee areal 1he syslem
needs anwe management so rhal lhe use sequenee Is
lmm lhe [up down, lhe mp darn rs dralned nno rhe
erhers iusl when rhey ean lake any lesldnzl warer As
eaeh ls emplred, evapnrihve surlsee reduees by
nnelhnd, nun-lunnh, unennn and so on obviously.
11w shall" rlrr serles Mm Dd!" llre «sun I| la Mun lu
ereare rwe senes ul 1 darns rarher lnan l senes a! s
dams Lrlse mum else .n lhe deserl, lhe seale ul
eperauensdeerdes elfinulty, .nd ln lhrsease smaller .s
rnrne ell enrl lune lml

Despne all lhe pmumal problems wnh salted sells
and warer. thaw are many me: n. desen ur dryllnd
luulhllls where heshwaler spnngs and gxuundwaltr
llees rhan zoo ppm sum an- ivallable, where shaded
valleysenn be salely dammed, and where suns are ape"
and lnedmnrne Endless problems and expense are
Avoided .l sueh sllcs ure surelully rdenlrlred and
seleeled wherever lueal lungAlenn loud pmvlsnm :5 0!
en uvex~ndlng eoneern

Miny rdeal sues lle m rhe rnner ullzysol spased lold
moumimsv where deep sends over elay held many
rnrllrons ul lures nl lreshwsler mum" l-nnn lne hrlls,
and all rhal rs needed is a mllablc wrndrnrll or snlar
pump le rarse lhrs waler u, a mesa ur nearby lull As
rnssl rarely exceeds lho l. 2n rn level rn wann desens,
n reused lank wlll lmgdle sub»|mpl(al' (mp on he
upper hrll slepes, and .leerdunus phnks nndrng : chill
lnnur am planud un rlre luwer slopes rhls snuanun rs
cnnunun m hlll munlnl wnh reslneled euld uplands
ll all surplus mum“ rs used m wel years In sel um
luresl lrees held m nursenss, sueh nlualuyns quukly
humus run anly susramable Mn sell-rehanr and lar less
nublm ln senous dmughl elleer ll .a all a rnalrer oi
ear-elul sue ehoree, Ksponslble behavlom, and medesl
seale

 

mun: ll .44
mm DAMS m SERIES mun: EVAPORAHOM

Eviwullnn his an In as we as m. ul 1 ml. darn ul rne sanu
:29:ch alldesen dams are deaw unnul .n seem

 

    
 

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358