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Title: Groundwater distribution in the recharge area of Ljubljanica springs Authors: ID Brenčič, Mihael (Mentor) More about this mentor... ID Gabrovšek, Franci (Mentor) More about this mentor... ID Blatnik, Matej (Author) Files: Matej_Blatnik.pdf (21,14 MB) MD5: 0B3DFFA6EBF1FFC935B950AC9987E13C   Language: English Work type: Doctoral dissertation Typology: 2.08 - Doctoral Dissertation Organization: FPŠ - Graduate School Abstract: Porečje Ljubljanice je s svojo kraško hidrologijo že stoletja predmet proučevanja. V začetku 19. stoletja so bila dela v največji meri posvečena preprečevanju ali vsaj omilitvi poplav na Planinskem polju. Obsežne raziskave v 70. letih 20. stoletja so na območju porečja Ljubljanice razkrile okvirne poti toka podzemne vode. Bolj natančno proučevanje vodonosnika z ugotavljanjem dimenzij in razporeditve kanalov ter dinamike pretakanja pa do zdaj ni bilo izvedeno. Nove speleološke raziskave in razvoj samodejnih merilnikov ponujajo možnost postavitve kakovostne merilne mreže tudi na težje dostopnih mestih. Namen pričujočega dela je zato nadgraditi poznavanje dinamike podzemne vode na območju porečja Ljubljanice z uporabo naprednih tehnik merjenja in interpretacij. Območje proučevanja je omejeno na severni del porečja Ljubljanice, in sicer med Planinskim poljem na jugu in izviri Ljubljanice na severu. Na tem območju je bila vzpostavljena merilna mreža s samodejnimi meritvami višine, temperature in specifične električne prevodnosti vode. Meritve so potekale na štirih požiralnikih na Planinskem polju, na treh izvirih Ljubljanice in osmih jamah z dostopom do podzemne vode. Poleg tega so bile opravljene še številne ročne meritve, na Agenciji RS za okolje (ARSO) pa so bili pridobljeni hidrološki in meteorološki podatki iz uradnih postaj. Na novo pridobljeni podatki so bili obravnavani glede na dotedanje znanje o vodonosniku. Mnoge pretekle ugotovitve so bile potrjene, številne interpretacije pa so bile zgrajene na novo. Te so bile povečini navezane na obliko vodonosnika (razporeditve in dimenzije kanalov) in njihov vpliv na nihanje vodne gladine, kar je bilo v nadaljevanju preverjeno z izgradnjo poenostavljenih konceptualnih in numeričnih modelov. Slednji so bili zgrajeni v programu EPA SWMM (Storm Water Management Model). V 3,5 letnem obdobju meritev je bilo veliko dogodkov s povišanim vodostajem, med njimi prek 15 takih, ko je bilo Planinsko polje poplavljeno. Dogodki so se med seboj zelo razlikovali tako po intenzivnosti kot tudi po trajanju, kar je predstavljalo raznovrstno zbirko podatkov. Najdaljši poplavni dogodek je trajal okoli tri mesece, v tem času pa se je vodna gladina v proučevanem vodonosniku dvignila do 66 m. Raziskave so potrdile pretekle ugotovitve, da se tok vode v vodonosniku prepleta (cepi in ponovno združuje) in da voda prek severnih požiralnikov Planinskega polja povečini teče proti zahodnim izvirom Ljubljanice, voda z vzhodnih požiralnikov Planinskega polja pa povečini proti vzhodnim izvirom Ljubljanice. Ugotovitve so pokazale tudi to, da na vzhodne izvire Ljubljanice pomembno vpliva tudi neposreden tok s Cerkniškega polja, kar se odraža zlasti s temperaturnimi odstopanji. Analiza višin podzemne vode je omogočila nove interpretacije o obliki kraškega vodonosnika. Na skoraj vseh merilnih mestih se je pokazalo obdobno upočasnjeno dviganje in spuščanje vode, kar nakazuje na prisotnost prelivnih kanalov. Takšni kanali so bili v nekaterih jamah že predhodno poznani (npr. Šerkov rov v Gradišnici, Skalni rov v Logarčku, Levi rov v Lijaku v Najdeni jami), medtem ko so v nekaterih jamah le predvideni (Veliko brezno v Grudnovi dolini, Andrejevo brezno 1). Obsežna merilna mreža, večletno obdobje meritev, stalne in samodejne meritve, uporaba naprednih tehnik interpretacij in preverjanje z modeli so omogočili raznovrstne analize in številne ugotovitve. Postopek se je izkazal kot primeren in bi bil uporaben tudi v drugih podobnih vodonosnikih. Podobno kot pretekle raziskave pa tudi ta pušča številna odprta vprašanja in možnosti za nadaljnje raziskave. Smiselne bi bile nadaljnje in bolj podrobne raziskave vpliva geoloških struktur, raziskave freatičnih in globokih regionalnih tokov, proučevanje vodne bilance in kakovosti vode, in nenazadnje tudi v splošnem boljše razumevanje poplavljanja Planinskega polja. Keywords: kraški vodonosnik, dinamika podzemne vode, poplavljanje, modeliranje, Planinsko polje, Ljubljanica Place of publishing: Nova Gorica Year of publishing: 2019 PID: 20.500.12556/RUNG-4307-9c46e352-b8c8-992e-e24d-cdc4226a3030  COBISS.SI-ID: 5313019  NUK URN: URN:SI:UNG:REP:ONATF8SJ Publication date in RUNG: 16.01.2019 Views: 4899 Downloads: 230 Metadata:     Cite this work Plain text BibTeX EndNote XML EndNote/Refer RIS ABNT ACM Ref AMA APA Chicago 17th Author-Date Harvard IEEE ISO 690 MLA Vancouver : Copy citation

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Secondary language

Language:	Slovenian
Title:	Porazdelitev podzemne vode v zaledju kraških izvirov Ljubljanice
Abstract:	The peculiar hydrology of the karstic recharge area of the Ljubljanica River has attracted researchers for centuries. In the beginning of the 19th century, the research focused on preventing the flooding of Planinsko Polje. A large research project in the 1970s resulted in the delineation of main water pathways in the recharge area. However, the dynamics of the groundwater and its relation to aquifer geometry has not been studied until recently. New speleological discoveries in addition to the recent development of automatic instruments with internal memory now allow for the distributed observation of groundwater with a high temporal resolution. The purpose of the present study is, therefore, to improve the knowledge of the groundwater dynamics in the recharge area of the springs of the Ljubljanica River through the use of the recently improved techniques for observation and interpretation. The study is focused on the northern part of the Ljubljanica River recharge area, between Planinsko Polje in the south and the springs of the Ljubljanica River in the north. There, a network with autonomous programmable instruments was established. Observations of water level, temperature, and specific electrical conductivity took place at four ponors on Planinsko Polje, three springs of the Ljubljanica River, and eight water-active caves between the ponors and the springs. Additionally, numerous field measurements of water parameters were collected and a large amount of hydrological and meteorological data from the Slovenian Environment Agency were obtained and used for the analysis. The newly obtained data were compared and analysed based on previous knowledge of the system. Many previous findings were confirmed, but also new interpretations were developed. Interpretations related to the influence of the underground geometry to water level variation were further tested using simplified conceptual and numerical models. For this, EPA SWMM (Storm Water Management Model) software was used. During the 3.5 year study period, more than 15 flooding events on Planinsko Polje occurred. The high variability in the intensity and duration of the events resulted in a rich dataset. The longest flood lasted for three months, and during this period, the water level in the entire aquifer was also at its highest; it rose up to 66 m. The measurements confirm previous findings that show that water in the aquifer interweaves (diverges and converges), and that water from the northern ponors of Planinsko Polje mostly flows towards the western springs of the Ljubljanica River, whereas water from the eastern ponors on Planinsko Polje mostly flows towards the eastern springs of the Ljubljanica River. Water coming directly from Cerknisko Polje also has an important influence on the eastern springs, which has been recognized based on the acquired temperature signals. Analyses of the water level hydrographs provide novel interpretations of the aquifer’s geometry. At all observation points, the water level hydrographs show inflection points with a temporarily slower increase and decrease of the water level, which indicate the presence of overflow passages. Some of the overflow passages were already known (in caves Gradišnica, Logarček and Najdena jama), whereas some were anticipated (in caves Veliko brezno v Grudnovi dolini and Andrejevo brezno 1). The large number of observation points, a long observation period, continuous autonomous measurements, and the use of new interpretation techniques including testing with numerical modelling provide a comprehensive analysis with many new findings. The results give a deeper view into the geometry of the aquifer, which is important because the aquifer has a strong impact on the water level dynamics.
Keywords:	karst aquifer, groundwater dynamics, flooding, modelling, Planinsko Polje, Ljubljanica River

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