Dodatek k članku »Dinamika podzemne vode med Planinskim poljem in izviri Ljubljanice, Slovenija” objavljenem v Acta Carsologica 48/2

The article of Blatnik et al. (2019) “Groundwater dynamics between Planinsko Polje and springs of the Ljubljanica River, Slovenia” published in Acta Carsologica, 48/2 focused on describing the hydrogeological behaviour of the aquifer between Planinsko Polje and the springs of the Ljubljanica River. The authors analysed the effect of different high water events that occurred between January 2015 and May 2018. Interpretations were based on hydrographs obtained by continuous measurements of water level, temperature and specific electric conductivity in selected ponors, springs and water active caves located in the area between Planinsko Polje and the springs of the Ljubljanica River. Through these interpretations, different conceptual hydrological models about the dynamics and directions of the flow in the aquifer have been proposed and tested. A flow connection was proposed between the Hrušica Plateau, estavelles located at the NW border of Planinsko Polje, and caves Gradišnica (W2) and Gašpinova Jama (W3) close to town Logatec. In this supplement, we provide new data recorded during an unusual hydrological event in August 2018. These further support and stress the importance of the connection between the Hrušica Plateau and Logatec region (W2 and W3).Članek »Dinamika podzemne vode med Planinskim poljem in izviri Ljubljanice, Slovenija«, ki je bil objavljen v Acta Carsologica 48/2, se je v osnovi osredotočil na raziskave pretakanja podzemne vode med Planinskim poljem in izviri Ljubljanice. Med rezultati so bila izpostavljena tudi nova dognanja o smereh pretakanja podzemne vode, ki so bila ugotovljena na podlagi zveznih meritev vodostajev, temperature in specifične električne prevodnosti vode ter testiranja z numeričnimi hidravličnimi modeli. Med drugim je bila ugotovljena domnevna smer pretakanja vode iz jam Veliko brezno v Grudnovi dolini (H1) in Andrejevega brezna 1 (H2), ki se nahajata na vzhodnem pobočju planote Hrušica. Od tu naj bi se voda v času visokih vodostajev pretakala v več smeri, in sicer proti estavelam pri Grčarevcu (SZ rob Planinskega polja) ter proti območju Logaškega ravnika, kjer se nahajata jami Gradišnica (W2) in Gašpinova jama (W3). Pričujoč dodatek k članku potrjuje pretekle domneve, v njej pa opisujemo manj običajen padavinski dogodek iz konca avgusta 2018, ko je na območju Hrušice padla mnogo večja količina padavin kot v preostalem delu porečja Ljubljanice. Rezultat je bil rahlo povišan pretok Unice, pri katerem je voda dosegla le vzhodno skupino požiralnikov na Planinskem polju. Posledično so se vodostaji v nekaterih dolvodno ležečih jamah Vetrovna jama pri Laški kukavi (E2) in Najdena jama (W1) zelo malo povišali (< 2 m). Mnogo bolj izrazit in zelo hiter je bil dvig vodostaja v jamah na pobočju Hrušice (do 37 m v H1). Porast vodostaja v jamah Gradišnica (W2) in Gašpinova jama (W3) je bil znaten (14 m), prav tako je do odziva in viška prišlo le malo po porastu v Velikem breznu v Grudnovi dolini (H1). Ob teh predpostavkah in dejstvu, da je bil dotok iz Planinskega polja zelo skromen, je hidrološka povezava med planoto Hrušico na eni strani Idrijske prelomne cone in območjem z Gradišnico (W2) in Gašpinovo jamo (W3) na drugi strani nedvoumna. Meritve s tem podkrepijo tudi domneve, da se na proučevanem območju nahajajo zožitve in različno prevodna območja Idrijske prelomne cone, ki vplivajo na zelo sinhrono dinamiko vodostajev. Proučevan padavinski dogodek je nakazal tudi, da je dotok iz območja Hrušice lahko zelo izdaten, saj se je najvišji pretok Ljubljanice (~71 m3/s) izrazito presegel tistega na Unici (11 m3/s). Pričujoč dodatek k članku torej potrjuje domneve v predhodno opisanem članku, hkrati pa tudi poudarja pomen dolgoročnih meritev v kraških vodonosnikih, ki v množici medsebojno podobnih zabeležijo tudi nekatere manj običajne, a za interpretacije zelo pomembne dogodke

Groundwater dynamics between Planinsko Polje and springs of the Ljubljanica River, Slovenia

Caves reaching the (epi)phreatic zone may provide the only access to groundwater in the internal parts of karst aquifers. Modern instruments enable unattended high frequency measurements of groundwater parameters in such caves. A network of distributed observation points may give new information on temporal and spatial pattern of groundwater flow. Such network, recording water level, temperature and specific electrical conductivity was established in all major ponors and active water caves of the karst aquifer between Planinsko Polje and springs of the Ljubljanica River, Slovenia. Up to three and a half years long records were analysed in view of available and relevant geological, speleological, meteorological and hydrological information, and basic hydraulic principles of the epiphreatic flow. The result of the interpretation were models of possible conduit networks of the three main flow subsystems draining Planinsko Polje. For each subsystem a hydraulic model comprising the main features of the inferred conduit network and inputs was made. The models were adjusted until their response to the typical flood situations gave a good qualitative fit to the response of the observation network. The results provide new insights into the mechanism of flood propagation through the system and its relation to the known conduit geometry. The hydraulic role of known cave passages is assessed and new flow pathways are proposed. Back-flooding within the aquifer causes an increase of head in the polje, followed by the activation of higher located ponor zones and flow pathways related to them. Hydrographs recorded in two caves located northwest from Planinsko Polje revealed pos sible high transmissivity zone of the Idrija Fault Zone and the mechanism of estavelles located at the polje’s north-western border. The approach taken in this work offers new insights into the relation between the conduit network geometry and flood mechanism. It can be used elsewhere in conduit-dominated systems with multiple accesses to groundwater flow and well constrained recharge.Key words: karst aquifer, epiphreatic zone, groundwater monitoring, hydraulic models, Planinsko Polje, Ljubljanica River.Dinamika podzemne vode med Planinskim poljem in izviri Ljubljanice, Slovenija Jame v epifratični coni običajno predstavljajo edini dostop do podzemne vode znotraj kraškega vodonosnika. Sodobni merilniki omogočajo kakovostne zvezne meritve različnih parametrov tudi v takšnih jamah. Merilna mreža z več lokacijami znotraj izbranega vodonosnika lahko ponudi nove podatke o časovni in prostorski dinamiki toka podzemne vode. Takšna merilna mreža, z meritvami višine, temperature in elektroprevodnosti vode, je bila vzpostavljena v vseh pomembnejših ponorih in vodnih jamah na območju med Planinskim poljem in izviri Ljubljanice. Do tri in pol leta dolgi nizi podatkov so bili analizirani z vidika razpoložljivih geoloških, speleoloških, meteoroloških in hidroloških podatkov ter osnovnih hidravličnih načel o epifreatičnem toku vode. Rezultat interpretacij so poenostavljeni modeli z domnevno razporeditvijo podzemnih kanalov v treh glavnih podsistemih, ki odvajajo Planisko polje. Za vsak podsistem je bil napravljen hidravličen model z dotokom in mrežo kanalov, ki najbolje ponazarja resnično stanje. Tekom raziskave so se hidravlični modeli nadgrajevali do takšne mere, da je simulacija vodnega toka zadovoljivo ponazarjala dogajanje, izmerjeno v resničnem okolju. Rezultati so prinesli nove ugotovitve o širjenju in dinamiki poplavljanja skozi sistem ter njihovo povezavo s poznano geometrijo proučevanega vodonosnika. Ocenjena je bila hidravlična vloga poznanih jamskih rovov, na podlagi njih pa interpretirane nove smeri pretakanja vode. Ugotovljeno je bilo tudi zajezitveno poplavljanje znotraj vodonosnika, ki vpliva tudi na vodostaj na polju in nadalje na aktivacijo višje ležečih požiralnikov ter njim sledečih kanalov. V dveh jamah severozahodno od Planinskega polja so višinski hidrogrami nakazali na obstoj bolj prepustnega območja Idrijske prelomne cone ter delovanje estavel na severozahodnem obrobju polja. Postopek, ki je bil uporabljen v pričujočem delu, omogoča nova dognanja o razporeditvi podzemnih kanalov in s tem povezano dinamiko poplavljanja v kraškem vodonosniku. Predstavljeno metodo je mogoče uporabiti tudi v drugih kraških sistemih z dobro razvitimi kanali, z več dostopi do toka podzemne toka vode in dobro poznanem dotoku v sistem.Ključne besede: kraški vodonosnik, epifreatična cona, spremljanje podzemne vode, hidravlični modeli, Planinsko polje, Ljubljanica

Razumevanje časovne spremenljivosti smeri toka v kompleksnem kraškem sistemu (Planinska jama, Slovenija)

Karst aquifers are abundant, but vulnerable water resources. Therefore, a deeper understanding of possible mechanisms that determine the properties of karst springs is crucial. In this work, we present an example of Unica Spring and Malni Spring, the two main outlets of a large karst system in the Notranjska karst region, Slovenia. Although the two springs share same catchment area, the flow distribution between them shows an interesting behaviour: At low-flow conditions, Malni Spring is the main outlet, while Unica spring receives almost no water. During high water events, discharge of Malni Spring stays limited and Unica Spring becomes the main outlet. We relate these observations to the local geometry of the channels and breakdowns in the remote part of the Planinska Jama (Planina Cave), called Mysterious Lake. There, waters from Rakov Škocjan and Javorniki aquifer merge and further diverge to both springs. At low water conditions, the outflow towards the Unica Spring is restricted by the breakdown, so that most of the inflow is directed towards the Malni Spring. With increasing recharge, the level in Mysterious Lake rises until the water starts to flow over the breakdown along a system of large channels (Rak Branch of Planinska Jama) to the Unica Spring. The breakdown level keeps the hydraulic head and the flow towards Malni Spring limited. To verify this scenario, a hydraulic conduit model was made based on the known and predicted channels, and inflows calculated from the historical data of discharge measurements at related springs and ponors. An inversion procedure was used to obtain a satisfactory fit to the observed discharge data and to constrain the selected model parameters. The model accurately reproduced the observed discharge behaviour under low- andhigh-flow conditions.Kraški vodonosniki so izdatni, a ranljivi vodni viri, zato je razumevanje mehanizmov, ki vplivajo na pretoke kraških izvirov, zelo pomembno. V prispevku obravnavamo primer izvira reke Unice v Planinski jami in izvira v Malnih, ki drenirata kompleksen vodonosnik Notranjskega krasa. Čeprav imata izvira skupno zaledje, je porazdelitev pretoka med njima precej nenavadna. Ob nizkem vodostaju prevladuje izvir v Malnih, izvir reke Unice v Planinski jami pa od skupnega zaledja prejema le majhen del vode. Ob visokem vodostaju je pretok izvira Malni omejen, izvir Unice pa postane glavni iztok sistema. V članku ta opažanja pojasnimo z lokalno porazdelitvijo kanalov in podora povezanih s Skrivnostnim jezerom v Planinski jami. Tja se steka voda iz Rakovega Škocjana in vodonosnika Javornikov in od tam odteka proti obema izviroma. Podorno območje pred Skrivnostnem jezerom ob nizkih vodah omejuje odtok proti izviru Unice, zato večino vode odteče proti izviru Malni. Ob naraščanju dotoka se nivo v Skrivnostnem jezeru dvigne nad podor, zato voda prosto odteče v velike rove Rakovega rokava proti izviru Unice. Višina preliva omejuje hidravlični tlak in pretok proti izviru Malni. Opisano dogajanje smo preverili s hidravličnim modelom, ki ga sestavljajo znani in predvideni kanali ter pretoki dotokov v Skrivnostno jezero, pri čemer smo slednje izračunali iz arhivskih podatkov pretokov izvirov in ponornic. Izbrane parametre hidravličnega modela smo prilagajali z inverznim algoritmom in dosegli dobro ujemanje modelskih rezultatov in arhivskih meritev ob različnih vodostaji

Understanding the temporal variation of flow direction in a complex karst system (Planinska Jama, Slovenia)

Karst aquifers are abundant, but vulnerable water resources. Therefore, a deeper understanding of possible mechanisms that determine the properties of karst springs is crucial. In this work, we present an example of Unica Spring and Malni Spring, the two main outlets of a large karst system in the Notranjska karst region, Slovenia. Although the two springs share same catchment area, the flow distribution between them shows an interesting behaviour: At low-flow conditions Malni Spring is the main outlet, while Unica spring receives almost no water. During high water events, discharge of Malni Spring stays limited and Unica Spring becomes the main outlet. We relate these observations to the local geometry of the channels and breakdowns in the remote part of the Planinska Jama (Planina Cave), called Mysterious Lake. There, waters from Rakov kocjan and Javorniki aquifer merge and further diverge to both springs. At low water conditions, the outflow towards the Unica Spring is restricted by the breakdown, so that most of the inflow is directed towards the Malni Spring. With increasing recharge, the level in Mysterious Lake rises until the water starts to flow over the breakdown along a system of large channels (Rak Branch of Planinska Jama) to the Unica Spring. The breakdown level keeps the hydraulic head and the flow towards Malni Spring limited. To verify this scenario, a hydraulic conduit model was made based on the known and predicted channels, and inflows calculated from the historical data of discharge measurements at related springs and ponors. An inversion procedure was used to obtain a satisfactory fit to the observed discharge data and to constrain the selected model parameters. The model accurately reproduced the observed discharge behaviour under low- and high-flow conditions

Deciphering the water balance of poljes: example of Planinsko Polje (Slovenia)

Poljes are flat closed karst depressions prone to regular flooding. The floods can be several meters high, last for months and damage significantly human infrastructures. To predict the maximum level reached, the polje water balance needs to be implemented. This technique encounters the difficulty that important part of the inflow and outflow flowing through many poljes is ungauged, as it is challenging to measure accurately the numerous springs and ponors activating temporarily with the rise of water level. This work aims to see whether this problem can be handled and the polje water balance reconstituted. To do so, a typical Dinaric polje is equipped with several water level stations installed over its surface and in the nearby water active caves. Combining a 1*1m digital elevation model of the polje surface with water levels and inflow records of the main two springs allowed assessing the variation of flooded volume and reconstructing the water balance. The highest total inflow values reached during the observed period were of about 140-150 m3/s, with up to a third of it being ungauged. In addition, the effect of a large estavelles group on the polje inflow and outflow could be identified, and helped to characterize the outflow, with values comprised between 65 and 75 m3/s. Finally, intense rainfall over the polje flooded surface showed to be a temporary important source of inflow. The values found by the water balance analysis have been used as input and calibration data in a numerical model reproducing the flood dynamics in the polje and its surrounding aquifer. Results validated both polje water balance and conceptual hydrogeological model. They justify the significance of combining water level measurements with a digital elevation model to monitor the floods. The method can be applied to other poljes flooding in a complex way of superposed input and output signals. Finally, the places to be equipped in priority if the polje has no measurement network or if available funding is limited are discussed

Les alternatives à la péridurale pour l'analgésie obstétricale

CAEN-BU Médecine pharmacie (141182102) / SudocSudocFranceF

Determination of inundation areas within karst poljes and intermittent lakes for the purposes of ephemeral flood mapping

The karst environment presents a special challenge when it comes to identifying groundwater/surface-water interactions. Existing definitions of areas of regular flooding in karst regions are too general and lack a measurable approach for the determination of flood-liable land. This paper proposes a means of specific definition and quantitative determination of intermittently flooded karst areas, which takes into account the extent, duration and frequency of flooding, and includes the identification of data sources and processing methods. The procedure, involving spatial layers, was developed using a pilot area and tested in three additional areas in Slovenia. The derived definition determines that flood-liable land within karst poljes and intermittent lakes comprise areas where stagnant water or stream overflow is present for at least 10 days/year over a period of 30 years, and these waters have direct contact with groundwater. The results show that the proposed procedure is applicable to areas with different geomorphological settings and to areas where the quantity and quality of available data vary. The study is an example of the practical application of knowledge on karst, as the findings can be used for short-term purposes (mapping flood areas, determination of habitats) and long-term purposes (study of impacts of environmental changes). Attention should be drawn to the lack of available data and the fact that the national networks of hydrological observatories are often too sparse for this purpose. This study raises awareness of these shortcomings and improves the planning or expansion of such a network in collaboration with experts

Understanding flooding in poljes: A modelling perspective

Poljes are large flat closed depressions that can be found in most karst areas around the world. They are prone to regular flooding, which occurs after abundant rainfall or snowmelt events. The floods can form several meters deep intermittent lakes that can persist for months. Human settlements around poljes have been traditionally positioned above the level of the most severe floods. However, many neighbouring villages expanded during the last decades to areas that might be endangered by large flood events. In addition, a recent study has shown that several poljes encountered floods of more severe amplitude in mid-Holocene due to a prevailing humid climate. As current knowledge of polje’s hydrology appears to be still insufficient, further research is needed. This work aims to identify the factors controlling polje flooding and evaluates their impact on the flood amplitude and duration. To do so, a list of parameters potentially controlling flooding is established. The relevance of each parameter is tested by using two idealized numerical models. The first one considers exclusively the polje from the springs to the ponors, whereas the second integrates the aquifer adjacent to the polje outflow side. First results show the usefulness of simple numerical models to identify the effect of each parameter on the flood amplitude and duration. The findings are combined to simulate a flood of medium intensity and long duration that occurred on a typical polje. A comparison of the results with real data demonstrates that the aquifer draining the polje needs to be considered to understand properly the flooding dynamics. The approach presented within this work has the potential to be used in other poljes encountering similar hydrological situations, but also lays foundation for flooding modelling in other karst areas