Karst Spring Discharges Analysis in Relation to Drought Periods, Using the SPI

Abstract

Based on the long hydrological time series, the correlation between karst spring discharge series and rainfall has been analysed, using the Standard Precipitation Index (SPI). Analysis has been focused on the drought periods. Data come from a large karst system (Campania, Southern Italy), in an area characterised by a distribution of the precipitation prevalently during autumn-winter period. Insufficient recharge due to poor rainfall results in flat spring hydrographs (with no peak during spring season) that indicate a continuously decreasing discharge. Specifically, it has been found that 12 months cumulative rainfall, expressed by SPI 12 , and spring discharge have similar trend. When SPI 12 will be equal or less that −1, springs reduce the discharge, and a flat spring hydrograph will be produced when SPI reaches value less than −1.5. In these cases, the prolonged shortage of accumulated rainfall causes a reduction in spring discharge also during the following year as well, pointing out a memory effect of the karst aquifer, and more complex rainfalldischarge relationship is observed.

Spatio-temporal patterns of meteorological droughts in the Balearic Islands (Spain)

“…The SPI has proved its ability to quantify drought severity at different time scales, and provides a powerful tool for the analysis and monitoring of meteorological droughts (Lana et al, 2001;Bonaccorso et al, 2003;Patel et al, 2007;Di Lena et al, 2014) and for the assessment of drought impacts on different systems, including river flows and reservoir storages (Vicente-Serrano et al, 2005;Lorenzo-Lacruz et al, 2010;Hannaford et al, 2011;Lorenzo-Lacruz et al, 2013a), vegetation activity (Pasho et al, 2011;Vicente-Serrano et al, 2012;Morán-Tejeda et al, 2013), soil moisture (Sims et al, 2002;Hirschi et al, 2011) and spring discharges and groundwater levels (Fiorillo et al, 2010).…”

Reconstruction of a Storm Map and New Approach in the Definition of Categories of the Extreme Rainfall, Northeastern Sicily

“…The transformation in the Standard normal distribution provides dimensionless values, and allows a direct comparison between the time series of Figure 10 (1, 3, 6, 12 and 24 h). Besides, it also allows the comparison of different hydrological parameters, such as spring discharge and rainfall [31]. The transformed historical data of Figure 10 have been plotted in Figure 11, fitted by the Standard normal distribution.…”

Karst aquifer draining during dry periods

“…(Fiorillo, 2009). In particular, 2001/02 was one of the most intense hydrological droughts that occurred in southern Italy (Fiorillo and Guadagno, 2010) and caused the historical minimum discharge in many karst springs. After the dry years of 2006/ 07 and 2007/08, the annual rainfall of the 2008/09 was one of the highest of the historical series, and increased the spring discharges much more than the mean.…”