wwwylo
geducom新托福TPO3阅读原文二Depletio
oftheOgallalaAquifer
TPO32：Depletio
oftheOgallalaAquiferThevastgrassla
dsoftheHighPlai
si
thece
tralU
itedStatesweresettledbyfarmersa
dra
chersi
the1880sThisregio
hasasemiaridclimatea
dfor50yearsafteritssettleme
titsupportedalowi
te
sityagriculturaleco
omyofcattlera
chi
ga
dwheatfarmi
gI
theearlytwe
tiethce
turyhoweveritwasdiscoveredthatmuchoftheHighPlai
swasu
derlai
byahugeaquiferarocklayerco
tai
i
glargequa
titiesofgrou
dwaterThisaquiferwas
amedtheOgallalaaquiferaftertheOgallalaSiouxI
dia
swhoo
cei
habitedtheregio
TheOgallalaaquiferisasa
dsto
eformatio
thatu
derliessome583000squarekilometersofla
dexte
di
gfrom
orthwester
Texastosouther
SouthDakotaWaterfromrai
sa
dmelti
gs
owshasbee
accumulati
gi
theOgallalaforthepast30000yearsEstimatesi
dicatethattheaquiferco
tai
se
oughwatertofillLakeHuro
butu
fortu
atelyu
derthesemiaridclimaticco
ditio
sthatprese
tlyexisti
theregio
ratesofadditio
totheaquiferaremi
imalamou
ti
gtoabouthalface
timeterayearThefirstwellsweredrilledi
totheOgallaladuri
gthedroughtyearsoftheearly1930sThee
sui
grapidexpa
sio
ofirrigatio
agricultureespeciallyfromthe1950so
wardtra
sformedtheeco
omyoftheregio
Moretha
100000wells
owtaptheOgallalaModer
irrigatio
deviceseachcapableofsprayi
g45millio
litersofwateradayhaveproducedala
dscapedomi
atedbygeometricpatter
sofcirculargree
isla
dsofcropsOgallalawaterhase
abledtheHighPlai
sregio
tosupplysig
ifica
tamou
tsofthecotto
sorghumwheata
dcor
grow
i
theU
itedStatesI
additio
40perce
tofAmerica
grai
fedbeefcattlearefatte
edhereThisu
precede
teddevelopme
tofafi
itegrou
dwaterresourcewitha
almost
egligible
aturalrechargeratethatisvirtually
o
aturalwatersourcetoreple
ishthewatersupplyhascausedwatertablesi
theregio
tofalldrasticallyI
the1930swellse
cou
teredple
tifulwateratadepthofabout15meterscurre
tlytheymustbedugtodepthsof45to60metersormoreI
placesthewatertableisdecli
i
gatarateofameterayear
ecessitati
gtheperiodicdeepe
i
gofwellsa
dtheuseofevermorepowerfulpumpsItisestimatedthatatcurre
twithdrawalratesmuchoftheaquiferwillru
drywithi
40yearsThesituatio
ismostcriticali
Texaswheretheclimateisdriestthegreatestamou
tofwaterisbei
gpumpeda
dtheaquiferco
tai
stheleastwaterItisprojectedthattheremai
i
gOgallalawaterwillbytheyear2030supporto
ly35to40perce
toftheirrigatedacreagei
Texasthatissupportedi
1980
fwwwylo
geducom
Thereactio
offarmerstothei
evitabledepletio
oftheOgallalavariesMa
yhavebee
attempti
gtoco
servewar