146
HIDROLOŠKI CIKLUS I PODZEMNE VODE
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Raspored voda na Zemlji
1,4 mrd. km3 u oceanima i morima
• ledenjaci i polarni led 43,4 mil. km3
• podzemne vode 15,4 mil. km3• jezera i rijeke 127.000 km3• atmosfera 15.000 km3• biosfera 2.000 km3
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Hidrološki ciklus
• kružni tok vode u prirodi–slijed prolaženja vode iz atmosfere na Zemlju kroz oborine, te njeno ponovno vraćanje u atmosferu isparavanjem
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Hidrološki ciklus
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vjetrovi nose vlagu prema obali
Postanak pustinja u sjeni kiše
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Moisture laden winds come
onshore.
količine vlage rastu i hlade se, uzrokujući precipitaciju ...
Postanak pustinja u sjeni kiše
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Moisture laden winds come
onshore
Moist airmass rise and cool,
causing precipitation…
... formirajući kišnu padinu okrenutu prema vjetru
Postanak pustinja u sjeni kiše
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Moisture laden winds come
onshore
Moist airmass rise and cool,
causing precipitation…
…resulting in a rainy windward
slope
zračne mase s izgubljenom vodom tonu i zagrijavaju se, reducirajući relativnu vlažnost ...
Postanak pustinja u sjeni kiše
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Postanak pustinja u sjeni kiše
Moisture laden winds come
onshore
Moist airmass rise and cool,
causing precipitation…
…resulting in a rainy windward
slope
Moisture-depleted airmass sink and warm,
reducing relative humidity…
... formirajući sjenu kiše na stražnjoj strani planine.
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149
Prosječni protok većih rijeka u svijetu
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Poroznost
•omjer volumena pora i ukupnog volumena stijene
– postotak stijene ili sedimenta koji se sastoji od šupljina
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Propusnost
• kapacitet stijene da propusti fluid, kao što je voda ili nafta, kroz pore i frakture
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Vodonosnik
• tijelo saturirane stijene ili sedimenta kroz kojeg se voda polako kreće
– vrlo propusni i saturirani vodom
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Poroznost• varira s:
– % cementa
– sortiranjem
– frakturiranjem
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Poroznost i propusnost različitih
tipova vodonosnika
Vrsta vodonosnika Poroznost Propusnost
Šljunak Vrlo visoka Vrlo visokaKrupno do sitnozrnasti pijesak VisokaVisokaSitnoszrnasti pijesak i silt Umjerena Umj. - niskaPješčenjak, umj. cementiran Umj. - niska NiskaFrakturirani šejl Niska NiskaMetamorfne stijene Niska Vrlo niskaNefrakturirani šejl Vrlo niska Vrlo niska
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151
Vrste vodonosnika
• otvoreni:
• zatvoreni:
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nesaturirana zona:
Otvoreni vodonosnik
saturirana zona:
vodno lice
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Vodno lice
• vrh saturirane zone podzemne vode
• razina do koje će voda narasti u zdencu i u otvorenom vodonosniku
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Dinamika otvorenog vodonosnika u uvjetima umjerene klime
Voda ulazi u podzemlje infiltracijom zbog kišenja ili otapanja snijega, i otječe putem izvora i rijeka. Nesaturirana zona varira u debljini kako pada vodno lice tijekom suhe sezone i raste u vlažnoj sezoni.
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U vrijeme vlažne sezone ...
Dubina vodnog lica oscilira između vode dodane precipitacijom (obnavljanjem) i ...
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U vrijeme suhe sezone …
... vode izgubljene evaporacijom uz otjecanje zbog bunara, izvora i tokova.
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Zatvoreni vodonosnik
područje obnavljanja
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Zatvoreni vodonosnik
piezometarska razinapodručje obnavljanja
nepropusnisloj
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• područje obnavljanja
• piezometarska razina
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154
Važne razlike:
• vodno lice: razina do koje će narasti voda u otvorenom vodonosniku
• piezometarska razina: razina do koje će narasti voda u zatvorenomvodonosniku
– arteški izvori
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Zatvoreni vodonosnik
piezometarska razinapodručje obnavljanja
arteški izvornepropusnisloj
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piezometarska razinapovršina tla
arteški izvor
nepropusnisloj
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Postanak konusne depresije
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Dinamika međudjelovanja slane
i slatke vode
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Darcyjev zakon
Q = A ( K x i)
Q = istjecanje (m3/dan)A = površina poprečnog presjeka (m2)K = hidraulička vodljivost (m/dan)i = hidraulički gradijent = h/l (bezdimenzijska veličina)
h - pad potencijala (m) na promatranom putu l (m)
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Darcyjev zakon
A=površina poprečnog presjeka
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Ogallalavodonosnik:
“Rudarenjepodzemne
vode”
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Površinski krški oblici• škrape• ponikve (vrtače) • jame• ponori• uvale• polje• estavela• posebno: vrulja
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Potpovršinski oblici krških područja
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škrape
vrtače (ponikve)
ponor
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Antropogena aktivnost koja može zagaditi podzemne vode
Industrija
Septičke jame
Pesticidi i navodnjavanjeOnečišćene lagune i bazeni
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Voda u kontinentalnoj kori
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Hidrotermalni sustavi
Voda ulazi u tlo infiltracijom
Zagrijana voda se izdiže
• topli izvori:
• gejziri:
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Hidrotermalni sustaviVoda ulazi u tlo
infiltracijom
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Hidrotermalni sustaviVoda ulazi u tlo
infiltracijom
Zagrijana voda se izdiže
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Topli izvori: nastaju na mjestima gdje zagrijana podzemna voda izlazi na
površinu
Voda ulazi u tlo infiltracijom
Zagrijana voda se izdiže
Hidrotermalni sustavi
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