The study of baseflow in mountainous areas of basin headwaters, where thecharacteristics of the often fractured materials are very different to thestandard issues concerning porous material applied in conventionalhydrogeology, is an essential element in the characterization andquantification of water system resources. Their analysis through recessionfragments provides information on the type of response of the sub-surfaceand subterranean systems and on the average relation between the storage anddischarge of aquifers, starting from the joining of these fragments into asingle curve, the Master Recession Curve (MRC). This paper presents thegeneration of the downward MRC over fragments selected after a preliminaryanalysis of the recession curves, using a hydrological model as themethodology for the identification and the characterization of quicksub-surface flows flowing through fractured materials. The hydrologicalcalculation has identified recession fragments through surface runoff orsnowmelt and those periods of intense evapotranspiration. The proposedmethodology has been applied to three sub-basins belonging to a highaltitude mountain basin in the Mediterranean area, with snow present everyyear, and their results were compared with those for the upwardconcatenation of the recession fragments. The results show the existence oftwo different responses, one quick (at the sub-surface, through thefractured material) and the other slow, with linear behaviour which takesplace in periods of 10 and 17 days respectively and which is linked to thedimensions of the sub-basin. In addition, recesses belonging to the dryseason have been selected in order to compare and validate the resultscorresponding to the study of recession fragments. The comparison, usingthese two methodologies, which differ in the time period selected, hasallowed us to validate the results obtained for the slow flow.
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