Recession hydrographs and time series analysis of springs monitoring data: application on porous and shallow aquifers in mountain areas (Aosta Valley)

Abstract

Aquifers in mountain areas are a strategic resource for the people who live there. To optimise future management, it is vital to understand hydrogeological systems from both geological and hydrogeological perspectives. Historically, methods such as hydrograph and time series analyses have been applied to characterise large karst systems. The aim of this paper was to apply these methods to small mountain springs supplied by porous and shallow aquifers. Specifically were made: (1) a comparison to understand which method better fits the depletion curve of the aquifers and (2) an application of time series analysis both by auto-correlation (analysis of individual series) and by cross-correlation methods (analysis of interrelationships between time series) on all the three parameters monitored from the probe (discharge Q, temperature T, electrical conductivity EC). These techniques were applied on four mountain springs located in the Italy North-Western Alps in the Aosta Valley Region. The results suggested that spring hydrograph and time series analyses on Q, T and EC parameters are useful tools for understanding the hydrodynamic behaviour of porous and shallow aquifers and how to make a proper management of the resource.