Hydraulic conductivities of fractures and matrix in Slovenian carbonate aquifers

Abstract

Izvle~ekV prispevku so s fraktalno Barkerjevo metodo analize ~rpalnih poizkusov dolo~ene vrednosti koeficientov prepustnosti in koeficientov elasti~nega uskladi{~enja tako za razpoke in za matriks v slovenskih karbonatnih vodonosnikih, predvsem v dolomitih. Vrednosti so podane za dolomite in apnence skupaj, kot tudi za posamezne vodonosnike, lo~ene po starostih kamnin in po litolo{kih zna~ilnostih. Podatki so zbrani iz poro~il o 397-ih vrtinah in vodnjakih, z omenjeno metodo pa je reinterpretiranih 79 ~rpalnih poizkusov. Koeficienti prepustnosti razpok so bistveno vi{ji od koeficientov prepustnosti matriksa, statisti~ne razlike med njimi pa so visoko zna~ilne. Podobno so zna~ilne tudi razlike med koeficienti elasti~nega uskladi{~enja v razpokah in v matriksu, pri ~emer so vrednosti v slednjem ve~je. Vrednosti vseh koeficientov se razlikujejo v posameznih vodonosnikih, razlike pa se da razložiti z diagenetskimi zna~ilnostmi, velikostjo zrn, stopnjo razpokanosti in ~istostjo kamnin. Primerjava med metodami, uporabljenimi v poro~ilih, in Barkerjevo metodo, kaže, da se podatki bolje prilegajo slednji metodi, ki je za kra{ko-razpoklinski tip kamnin tudi bolj ustrezna. AbstractHydraulic conductivities and specific storage coefficients of fractures and matrix in Slovenian carbonate aquifers were determined by Barker's method for pumping test analysis, based on fractional flow dimension. Values are presented for limestones and mainly for dolomites, and additionally for separate aquifers, divided by age and lithology in several groups. Data was obtained from hydrogeological reports for 397 water wells, and among these, 79 pumping tests were reinterpreted. Hydraulic conductivities of fractures are higher than the hydraulic conductivities of matrix, and the differences are highly statistically significant. Likewise, differences are significant for specific storage, and the values of these coefficients are higher in the matrix. Values of all coefficients vary in separate aquifers, and the differences can be explained by diagenetic effects, crystal size, degree of fracturing, and carbonate purity. Comparison of the methods, used in the reports, and the Barker's method (being more suitable for karstic and fractured aquifers), shows that the latter fits real data better. UvodV Sloveniji je delež odvzema podzemne vode proti razpoložljivi koli~ini v vodnih telesih podzemne vode s prevladujo~imi vodonosniki kra{kega, razpoklinskega in me{anega tipa poroznosti {e vedno majhen (povpre~no 12 %; ANDJELOV et al., 2006). Kljub dokaj majhnem deležu postajajo ti vodonosniki ~edalje pomembnej{i vir pitne vode. V primerjavi z medzrnskimi so {e vedno manj raziskani, predvsem zaradi svoje heterogenosti in posledi~no zahtevnej{ih analiz, zato je o njih znanih manj podatkov, med katere npr. sodijo podatki o prepustnosti oz. izdatnosti. V Sloveniji se veliko raziskovalcev ukvarja z razli~nimi lastnostmi karbonatnih kamnin, toda sistemati-~n ih analiz parametrov in predvsem analiz, ki bi povezovale vrednosti parametrov z dejanskimi lastnostmi ka...

Gravitational sliding of the carbonate megablocks in the Vipava Valley, SW Slovenia

“…On a micro level, erosion depends also on the steepness of the flysch slopes, with steeper relief allowing better drainage due to water-retaining clay minerals washed into lower parts (Jamšek Rupnik, Čuš and Šmuc 2016). Also, water can accumulate as groundwater in the carbonate blocks, as they are strongly fractured, karstified and permeable (Verbovšek 2008;Verbovšek and Veselič 2008), and some water can also be accumulated in carbonate scree, depositing above the blocks. In both cases, the presence of water can intensify the weathering of flysch below the blocks and deteriorate its mechanical properties.…”

Hydrogeochemistry and isotope geochemistry of Velenje Basin groundwater

“…Pliocene and Pliocene 2, 3 aquifers were introduced due to the fact that in some cases, it was not possible to attribute the water to a single aquifer, so a combination of all (Pliocene) or two aquifers (Pliocene 2, 3) was used instead. Hydrogeological properties of these dolomites are presented in detail in the works of verBovšeK & veselič (2008) and verBovšeK (2008a, 2008b. Groundwater recharging the Velenje Basin is drained by hanging filters to prevent inrush of water into the mine.…”

An Integrated Approach to Characterising Sulphur Karst Springs: A Case Study of the Žvepovnik Spring in NE Slovenia

“…Therefore, the spring water represents a mixing of (1) deeper waters, which are in contact with the gypsum and/or anhydrite (proven by the results of δ 34 S SO4 and δ 18 O SO4 ), as both minerals appear regionally in both Upper Permian carbonate rocks and Lower Triassic carbonate-clastic successions [42,71], and (2) shallow waters, which flow through the Middle Triassic carbonate aquifer, which outcrops on the surface in the immediate proximity of the Žvepovnik spring. Both types of water are likely in geochemical equilibrium with gypsum and/or anhydrite in the deeper aquifer and also with dolomite (and calcite) in the shallow carbonates and become undersaturated with gypsum and/or anhydrite when mixed near the surface, as the shallow carbonates are more permeable [72][73][74]. Carbon in the water comes from the non-equilibrium carbonate dissolution by carbonic acid produced from soil zone CO 2 , as confirmed by δ 13 C DIC values.…”

“…and/or anhydrite when mixed near the surface, as the shallow carbonates are more permeable [72][73][74]. Carbon in the water comes from the non-equilibrium carbonate dissolution by carbonic acid produced from soil zone CO2, as confirmed by δ 13 CDIC values.…”