Analysis of spring discharges during droughts: Example from karst systems of Southern Italy

Abstract

Analyses of spring discharges of a large karst system (Campania, Southern Italy) have been carried out to quantify the relation of rainfall and droughts. Due to a Mediterranean climate and hydrogeological conditions of the aquifers, spring hydrographs are characterised generally by one annual smoothed peak during spring season and a negligible quick flow component. Insufficient recharge due to poor annual rainfall can cause continuous decreasing discharge at springs, producing flat hydrographs (with no peak). Flat spring hydrographs induces a reduction in discharge during the following year as well. Thus, aquifers present a memory effect, which amplifies periods of poor rainfall. Droughts also appear to be induced by consecutive years with lower than average rainfall. Due to a long historical series and the specific karst spring regime, a flat hydrograph can be forecast as early as winter, providing a useful tool for water management.