ANALIZA RECESJI WYDATKU ŹRÓDŁA POD WYSOKIM DZIAŁEM (PIENIŃSKI PAS SKAŁKOWY) W ŚWIETLE OBSERWACJI LIMNIMETRYCZNYCH

Abstract

THE DISCHARGE ANALYSIS BASED ON LIMNIMETRIC MONITORING: SPRING POD WYSOKIM DZIAŁEM, PIENINY KLIPPEN BELTAbstract. The paper describes the results of 9-year stationary monitoring of the spring Pod Wysokim Działem, located in the Pieniny Mts. The monitoring of water level with application of automatic limnimeters and periodically measured spring discharge allowed recording detailed variations of the discharge especially in the periods of its own regime independent of temporary recharging events, like snowmelt or rainfall. It drained only its own groundwater reservoir. Based on the analysis of spring discharge and daily sum of precipitation, 20 periods of discharge recession of 7 to 64 days-long each were selected. The Maillet equation, widely used in hydrogeology. was applied to mathematical description of the recession curves of the spring. Each time, the recession coefficient a, as well as the storage capacity of the spring and residence time of water in the system, were calculated. The obtained values of recession coefficient a from 0.005 to 0.01 d-1 are generally lower than those known from literature, namely: 0.04-0.7. It probably suggests the low permeability of illitic weathering, which hampers the groundwater inflow to the spring. On the other hand, low values of the storage capacity (<50 000 m3) and short residence time of water in the system (in a range of a few months) suggest that the spring rather drains a small local groundwater reservoir.