Caracterización del Sistema Kárstico de Olalde a partir del análisis del hidrograma del manantial

Abstract

The Olalde spring is the main drain of the karstic system of the Iimestome of San Miguel de Ereñozar; the aquifer is also recharged through sinks (ponors), by the surface run off from drained closed basins, partially occupied by impermeable materials. The mean flow of the spring is 240 I/sec, with a very high variability: the flow was 2633 I/sec at the beginning of the recession curve analyzed here and 18 I/sec the last day considered. The value of the depletion coefficient α is 0.032 day^-1 and the duration of the recession curve "sensu stricto" is 21.5 days. The values of the velocity of infiltration coefficient ἠ and the heterogeneity coefficient ξ are, respectively, 0.0465 and 3.49 day^-1. The parameters i (=0.114) and k (=0.025) suggest a very fast recession and a very poor regulation power; this behaviour is typical of intensely karstified systems with a very well developed subterranean drainage network which are characteristic of the realm of huge spelaeological caves. These facts reveal that the prospects of regulation of the spring are not very promising and would involve, in any case, a small part of the whole discharge.