THE DISCHARGE VARIABILITY OF SOME KARST SPRINGS IN BULGARIA STUDIED BY TIME-SERIES ANALYSIS

The discharge variability of some karst springs in Bulgaria has been i nvestigated in detail within a region situated in the semiarid zone wh ere most of the principal processes controlling spring outflow (evapot ranspiration, snow accumulation, karstic functioning) are significant. While the karstification was notable in the Kotel and Bistretz spring s with a predominance of quickflow, in the Beden system the baseflow w as higher and had a behaviour similar to a porous aquifer. Univariate and bivariate spectral analyses were applied as a suitable tool in pre paration for a further application of precipitation-discharge relation ship models.