Marian Fendek

Groundwater Drought in the Nitra River Basin - Identification and Classification

Groundwater Drought in the Nitra River Basin - Identification and Classification Drought as a natural phenomenon becomes more often the subject of the research. It is because of the increasing frequency of extreme climatic events also in mild climate conditions. Groundwater drought indices could be derived for different groundwater parameters, among them for base flow, groundwater head stage, spring yield, or groundwater recharge. Base flow drought assessment methods were proposed in the paper. Base flow values were separated from the discharge hydrograms using the new HydroOffice 2010 program package, lately developed by Gregor. The base flow drought severity index was applied, calculated as the value of the base flow drought deficit volume divided by the drought duration. After that, the standardized base flow drought severity index was proposed as the ratio of the base flow drought index and the average long-term annual base flow. Proposed methods were applied in the Nitra River basin. Base flow drought occurrence was characterized also from the seasonality point of view. Sucho v Podzemnej Vode v Povodí Toku Nitra - Identifikácia a Klasifikácia Sucho ako jeden z prírodných javov sa čoraz častejšie stáva predmetom výskumu. Príčinou je narastajúca frekvencia výskytu extrémnych klimatických situácií aj v miernych zemepisných šírkach. Klasifikačné kritériá výskytu sucha v podzemnej vode možno odvodiť pre rôzne parametre podzemnej vody, napríklad pre hodnoty podzemného odtoku, úrovne hladiny podzemnej vody, výdatnosti prameňa alebo dopíňania zásob. V príspevku sú navrhnuté metódy hodnotenia sucha v podzemnom odtoku. Hodnoty podzemného odtoku boli z hydrogramu prietokov odseparované pomocou nového štatistického balíka HydroOffice 2010, ktorý bol v nedávnej minulosti vytvorený Gregorom. Index závažnosti sucha bol vypočítaný ako podiel nedostatkového objemu podzemného odtoku a dížky trvania sucha. Následne bola hodnota indexu závažnosti sucha normalizovaná vydelením dlhodobou priemernou hodnotou podzemného odtoku. Navrhnutá metodika bola použitá pre povodie toku Nitra. Výskyt sucha v podzemnej vode bol hodnotený aj z pohľadu jeho sezónnosti.

Global drivers effect in multi-annual variability of runoff

Abstract Changes in runoff parameters are very important for Slovakia, where stream-flow discharges, being supplied by precipitation and groundwater runoff, are preferentially influenced by climatic conditions. Therefore, teleconnections between runoff parameters, climate parameters and global atmospheric drivers such as North Atlantic Oscillation, Southern Pacific Oscillation, Quasi-biennial oscillation and solar activity were studied in the Nitra River Basin, Slovakia. Research was mostly based on records of 80 years (1931-2010) for discharges and baseflow, and 34 years for groundwater heads. Methods of autocorrelation, spectral analysis, cross-correlation and coherence function were used. Results of auto- correllograms for discharges, groundwater heads and base flow values showed a very distinct 11-year and 21-year periodicity. Spectrogram analysis documented the 11-year, 7.8-year, 3.6-year and 2.4-year periods in the discharge, precipitation and air temperature time series. The same cycles except of 11-years were also identified in the long-term series of the North Atlantic Oscillation and Southern Pacific Oscillation indices. The cycle from approximately 2.3 to 2.4-years is most likely connected with Quasi-biennial oscillation. The close negative correlation between the North Atlantic Oscillation winter index and the hydrological surface and groundwater parameters can be used for their prediction within the same year and also for one year in advance.

The pre-Cainozoic basement delineation by magnetotelluric methods in the western part of the Liptovská kotlina Depression (Western Carpathians, Slovakia)

Abstract The geology and hydrogeology of the Liptovská Kotlina Depression were studied by means of new geophysical methods. Controlled source audio-frequency magnetotellurics enabled us to delineate the relief of the pre-Cainozoic basement in the western part of the Liptovská Kotlina Depression into two segments with different lithostratigraphic units. Our complex findings disprove the interconnection between the Bešeňová and Lúčky water bearing structures located in the study area. The results were interpreted in the form of a resistivity cross section and resistivity model. The geological interpretation of the obtained results, taking into account the other geophysical and geological constrains showed that the pre-Cainozoic basement has a tectonically disrupted, broken relief. The Bešeňová and Lúčky structures appear to be isolated by the Palaeogene sediments (sandstone, claystone) and in the deeper part also by marly carbonates and marlstones of the Jurassic age belonging to the Fatricum. It was confirmed that the structural connectivity of geothermal aquifers in the area between the Bešeňová and Lúčky–Kaľameny should not exist. The assumption of different circulation depth was also confirmed by geothermometry and existing radiocarbon analyses applied on groundwater in both areas.