The objective of this study is to make a conceptual and numerical model of the groundwater flow system which will improve the understanding of the groundwater cycle in the area of the Čenkov Valley, Slovakia. Extreme deficits of atmospheric precipitation and thereof resulting periods of low water flows and discharges could very negative impact the water management. Increasing water consumption in the future will be the most critical in strong and intensive dry periods. Almost every climatic zone could suffer from drought, although its features could considerably vary from region to region. The study is handling with creating, calibration and verification of numerical model of groundwater flow in the reparian alluvial aquifer of the Čenkov Valley in south-east part of the Danubian lowland for minimal anthropogenic disrupted natural conditions in the past and quasi-steady deficit water regime of the area. The conceptual model is based on data from earlier studies in the area complemented with data collected in the field. Results of model solutions are presented in the study - groundwater level, filtration velocity vectors, groundwater paths by particle tracking and water budget of study area. Created numerical model could be used for simulation of underground dam function, which belongs to the types of artificial recharge of reparian alluvial aquifer management, and also for creating prognostic scenarios concerning expected climatic changes. Additional future work may include adding a solute transport model to the flow model. and Cieľom predloženej štúdie je vytvorenie koncepčného a numerického modelu systému prúdenia podzemnej vody na území Čenkovskej nivy na Slovensku. Extrémne deficity atmosférických zrážok a z toho vyplývajúce obdobia nízkych vodných stavov a prietokov môžu vplývať na vodné hospodárstvo veľmi negatívne. Zvýšená spotreba vody bude v budúcnosti najkritickejšia práve počas drasticky suchých periód. Takmer každá klimatická zóna môže trpieť suchom, hoci jeho charakteristiky sa môžu od regiónu po región značne líšiť. Štúdia sa zaoberá tvorbou, kalibráciou a verifikáciou numerického modelu prúdenia podzemnej vody v pririečnom hydrogeologickom kolektore Čenkovskej nivy v juhovýchodnej časti Podunajskej roviny, za minimálne antropogénne narušených prírodných podmienok v minulosti a kvázi ustáleného deficitného vodného režimu územia. Koncepčný model je založený na údajoch z predošlých štúdií doplnených o údaje zhromaždené v teréne. V štúdii sú prezentované výsledky modelového riešenia - poloha hladiny podzemnej vody, vektory filtračnej rýchlosti, smery prúdenia podzemnej vody prostredníctvom trasovania pohybu častíc a vodná bilancia územia. Vytvorený numerický model môže byť využitý na simuláciu funkcie podzemnej priehrady, ktorá patrí medzi typy umelého nasycovania pririečneho aluviálneho kolektora a tiež pri tvorbe prognostických scenárov, zaoberajúcich sa klimatickými zmenami. Doplnková budúca štúdia sa môže venovať pripojeniu transportného modelu chemických látok k prezentovanému tokovému modelu.
The paper presents an evaluation of the combined use of the HYDRUS and SWI2 packages for MODFLOW as a potential tool for modeling recharge in coastal aquifers subject to saltwater intrusion. The HYDRUS package for MODFLOW solves numerically the one-dimensional form of the Richards equation describing water flow in variablysaturated media. The code computes groundwater recharge to or capillary rise from the groundwater table while considering weather, vegetation, and soil hydraulic property data. The SWI2 package represents in a simplified way variable-density flow associated with saltwater intrusion in coastal aquifers. Combining these two packages within the MODFLOW framework provides a more accurate description of vadose zone processes in subsurface systems with shallow aquifers, which strongly depend upon infiltration. The two packages were applied to a two-dimensional problem of recharge of a freshwater lens in a sandy peninsula, which is a typical geomorphologic form along the Baltic and the North Sea coasts, among other places. Results highlighted the sensitivity of calculated recharge rates to the temporal resolution of weather data. Using daily values of precipitation and potential evapotranspiration produced average recharge rates more than 20% larger than those obtained with weekly or monthly averaged weather data, leading to different trends in the evolution of freshwater-saltwater interfaces. Root water uptake significantly influenced both the recharge rate and the position of the freshwater-saltwater interface. The results were less sensitive to changes in soil hydraulic parameters, which in our study were found to affect average yearly recharge rates by up to 13%.