Temporal variability of springs in catchment areas located in the Sudeten Mountains

This paper focused on are the results of research into the freshwater springs occurring in the crystalline and compact sedimentary rocks in the Sudeten Mountains. The research consisted of three series of measurements taken in the hydrological year 2013 in four test catchments (Machowski Stream, Inflow at the foot of Mount Grodziec, Podgorna, Mostowy Stream). Data analysis indicated that the number of springs, spring discharge and physicochemical properties of the water were subject to significant temporal variation. The temporal variability of the spring density index ranged from 7 to 31%. Temporal variations in the total yield of the springs fluctuated between 34 and 63% and the minimum discharge variability index exceeded 100%. The study indicated that water flow in areas consisting of compact sedimentary rocks such as sandstone and marl is much more diffuse than in areas that are comprised primarily of crystalline rocks, which accounts for a lower yield and a decrease in temporal spring discharge variability. In areas made up of crystalline rocks, the higher yield and the higher spring discharge variability index point to cracks and fissures as the main recharge component, a feature characteristic of aquifers with high conductivity and low storage capacities.