hydrology Article Evaluation of Groundwater Resources in Minor Plio-Pleistocene Arenaceous Aquifers in Central Italy Diego Di Curzio , Sergio Rusi * , Alessia Di Giovanni and Emanuele Ferretti   Citation: Di Curzio, D.; Rusi, S.; Di Giovanni, A.; Ferretti, E. Evaluation of Groundwater Resources in Minor Plio-Pleistocene Arenaceous Aquifers in Central Italy. Hydrology 2021, 8, 121. https://doi.org/10.3390/hydrology 8030121 Academic Editors: David Brauer, Nathan Howell and Ryan Bailey Received: 8 July 2021 Accepted: 11 August 2021 Published: 16 August 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Department of Engineering and Geology (InGeo), Università degli Studi “G. d’Annunzio” Chieti-Pescara, 66100 Chieti, Italy; diego.dicurzio@unich.it (D.D.C.); alessia.digiovanni@unich.it (A.D.G.); emanueleferretti6@gmail.com (E.F.) * Correspondence: sergio.rusi@unich.it Abstract: The hilly landscape of the Periadric area in Central Italy is characterized by mainly marly– clayey foredeep basin deposits (Plio–Pleistocene age). These lithotypes are generally considered aquicludes, if compared with the regional limestone aquifers of Apennines. However, a coarsening upward trend characterizes the upper portion of this stratigraphic sequence, with arenaceous deposits and even conglomerates on the top. From a geomorphological viewpoint, the areas with coarser outcrops show a flat shape and sub-vertical slopes, like boundaries. At the base of these scarps, springs can be found at the interface between coarse and fine deposits, whereas these arenaceous bodies are actual aquifers. Until now, the hydrodynamics and hydrochemical features of this kind of aquifer have not been investigated deeply, because they have always been considered a worthy water resource. However, they could play a crucial role in integrated water management, especially to cope with climate changes and drought periods. Considering these, the main purpose of this study was to investigate from a hydrogeological point of view and to assess the groundwater quantity and quality. Five examples throughout the Abruzzo region were considered. For evaluation and comparisons between water resources, the water volume that infiltrates yearly at each squared kilometer of an aquifer (Mm 3 /y/km 2 ) was applied. This value was calculated through three different approaches to provide a recharge estimation for this kind of aquifer that is as exhaustive and representative as possible. The results allowed us to characterize the hydrogeological model and to quantify the resources between 0.1 and 0.16 Mm 3 /y/km 2 , to be suitable for multi–purpose utilization. Keywords: minor arenaceous aquifer; groundwater budget; yearly specific recharge; historical tapping systems; integrative water resources 1. Introduction In recent decades, population growth, industrialization, and urbanization have gen- erated an ever-increasing demand for fresh water [1–3]. This has led to a huge transition from small and local water resource exploitation and distribution networks to regional and more integrated systems that bring water from springs and wells over great distances. Traditionally, areas on the Mediterranean, specifically Central Italy, sourced water from local small springs or wells near villages and towns [4]. Now, water for drinking, irrigation, hydroelectricity production, and manufacturing mainly come from regional karst or alluvial aquifers [5–11]. As a matter of fact, the regular steady baseflow of springs and rivers is directly connected to the amount of groundwater [12]. The principal aqueducts, which have a capillary pipeline system on the order of hundreds of kilometers, distribute groundwater to both the Tyrrhenian and Adriatic coasts (Figure 1) mainly from the karst aquifers in the Apennine Mountains [13–16] and to a lesser extent from alluvial aquifers [17–21]. Hydrology 2021, 8, 121. https://doi.org/10.3390/hydrology8030121 https://www.mdpi.com/journal/hydrology