Miriam Fendekova

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.

Groundwater Drought Occurrence in Slovakia

Groundwater regime and drought occurrence studies are very important for Slovakia, where groundwater is preferentially used for drinking water supply. It was shown by several studies that the groundwater drought occurs in Slovakia more often since the 1980s, causing problems in various sectors of the Slovak economy. Groundwater drought can be described either through groundwater heads, baseflow, groundwater storage or by the spring yield change. As the main reasons for groundwater drought occurrence, the natural factors and human activities can be mentioned. The amount of groundwater stored in the rock environment primarily depends on the water availability in the area and on the storage capacity of the rock environment itself. The lack of precipitation, high air temperature and the unfavourable storage properties of the rock environment belong to the main natural factors conditioning the groundwater drought occurrence. The groundwater over-abstraction also could increase the sensitivity of the local hydrological system to drought development. The groundwater drought studies for the Slovak territory were first published in the 1990s as a result of drought which hit the territory in the 1982–1984 period. After that, several important scientific works were performed to analyse the factors of drought development, occurrence and impacts on nature and social sphere. Baseflow drought, groundwater head drought and spring yield decrease were studied as presented in the chapter.

Evaluation of the Aggressiveness of Slovak Mineral Water Sources

Abstract The aggressive properties of natural waters arise due to their specific physical properties and chemical composition. The latest analyses of certified natural and healing mineral water sources according to Act No. 538/2005 were used for the evaluation. A total of 53 sources in 26 localities were evaluated; they comprised 25 sources of bottled natural mineral and healing waters and 28 sources of natural healing waters in 9 spas. The aggressiveness of the water against concrete was weak (17 sources), medium (17 sources), or none (19 sources). The aggressiveness was mostly caused by low pH values and/or increased SO42− content. Their corrosiveness to metal was mostly very high. The results showed that the disintegration of concrete building constructions, well casings and pipelines could occur in most of the evaluated localities in the case of mineral water contacting them. Therefore, preventive measures are necessary.