A Preliminary Assessment of Young Water Fractions in Groundwater from Alluvial Aquifers Facing the Northern Italian Apennines

Abstract

This study sums up the first estimates of the young water fraction (Fyw; here understood as the percentage proportion of groundwater passing through the well’s screen and younger than approximately 2–3 months) from groundwater collected in 75 wells from alluvial fans facing the northern Italian Apennines of Italy. The Fyw estimates were based on a monthly dataset of water-stable isotopes (oxygen-18 (18O)) from surficial water (9 rivers), while the dataset of groundwater (75 wells) consisted of three-monthly isotopic data. In the cases of surficial water and stable isotopes, these lasted over the period of January 2003 to December 2007, while in the case of groundwater, the data were collected from January 2005 to December 2007. The values of Fyw were estimated by means of a sine-wave fitting technique; the results made evident the presence of unexpectedly reduced differences between groundwater. In particular, shallower groundwater hosted in aquifers from the apical parts of the alluvial fans (i.e., aquifers characterized by the coarsest materials such as gravels and sands, and closest to the recharge areas) showed similar values of Fyw to the deepest aquifers from the distal parts; however, former studies mentioned here evidenced the existence of poorly recharged old groundwater. Our results seem to confirm a complex behavior of these aquifers compared with what had previously been thought.

Assessing Vulnerability of Regional-Scale Aquifer-Aquitard Systems in East Gulf Coastal Plain of Alabama by Developing Groundwater Flow and Transport Models

“…Their approach captured the general trend of vertical distributions of stable isotope values (δ 2 H, δ 2 O, and 4 He), providing indexes of GWV for a 3D, basin-scale, bedrock aquifer. Many other applications have shown that backward particle tracking built upon a calibrated groundwater flow field is a promising process-based approach to assess regional-scale GWV [24][25][26][27][28][29][30][31]. This approach will be used in this study.…”