Change of Groundwater Flow Characteristics After Construction of the Waterworks System Protective Measures on the Danube River – A Case Study in Slovakia

Abstract

The waterworks construction affects the hydrological regime of the flow of groundwater in the river alluvia that is usually in the hydrodynamic relation to the regime of the fluctuation of the surface watercourse level. To elaborate the prognosis of the changes in the regime of groundwater means to determine their sequence in time for the entire period of their creation until the final stable status is reached. It has to be made on the basis of the knowledge of hydrogeological situation within the territory and the contemporary regime of groundwater. The creation of such changes may be invoked by natural changes or also anthropogenic interventions into the water situation within the territory. The above implies this is the unsteady flow task from hydrodynamic point of view. It is natural since groundwater flow has always somehow the character of unsteady flow. It is implied by natural conditions of their supply and drainage. The regime of supply and drainage of groundwater in water-bearing collectors depends upon the factors not changed in time, so in general, the mode of fluctuation of groundwater level is affected by the changes in time as well and therefore it is unsteady. However, if the conditions of supply and drainage of groundwater are changed in time negligibly, or if the area of interest of the water-bearing collector is located in a certain sufficient distance from the source of supply and drainage point, the flow of groundwater may be practically considered to be stable. The time slope of the forecast changes within the determined area of flow then shall, in addition to other conditions, depend upon time changes in surface and groundwater at its edges, i.e. in the areas of supply or drainage of groundwater. The forecast time changes shall then depend upon the character of the peripheral impacts, thus they shall be different in the case of the natural changes in hydrological conditions and different in the case of artificial structural interventions into contemporary hydrological conditions. In particular, the morphological changes in the river bed, contents of suspended sediments in the watercourse and natural colmatage of the watercourse belong amongst the natural changes in the hydrological conditions of the territories affecting the groundwater regime (Veliskova, 2010; Gombos, 2008). All the technical structural measures amending the conditions of supply and drainage