Episodes 2013; 36(2): 105-114
Published online June 1, 2013
Copyright © International Union of Geological Sciences.
Sebastian Buczyñski* and Marek Wcislo**
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
The level of water in aquifers depends mostly on precipitation. However, recent research has shown that greater annual rainfall values do not necessarily trigger off an automatic increase in groundwater recharge. The lowering of the water table may result not only from lower precipitation, but also from intensification in evaporation and a decreased natural infiltration capacity of dried-down soil. Also extreme rainfall conditions (such as torrential rain and storms) that occur in mountainous regions may, owing to a rise in surface runoff and decreased infiltration, lead to a lower groundwater recharge.
Studies seem to indicate that in the upper drainage basin of the river Muszynka (southern Poland) a ten-year period of precipitation equal to 62% of the long-term average is likely to cause the groundwater levels (present in the Palaeogene flysch formations) to drop by two metres in river valleys and 40 metres in watershed zones and central parts of slopes. This will result in a reduction of groundwater resources related to aquifer compressibility makes up only 3.4x10-5 % of the annual underground runoff; therefore, it is not necessary to include it in the overall water balance.