Abstract
Nowadays, climate changes and increased water demand for human and agricultural purposes pose important questions for the groundwater management of alluvial aquifers facing the northern Italian Apennines. The large groundwater withdrawals, coupled with an overall worsening of the water quality, requires a detailed knowledge of the recharge mechanisms of these aquifers that can be useful for further adaptation measures. Concerning the recharge area of the alluvial aquifers (i.e., apices made up of gravelly materials), the present study investigates a dataset made up of 282 water samples for which stable isotopes oxygen-18 (18O) and deuterium (2H) are available. The latter involves precipitations (three rain gauges), surface water (five rivers) and groundwater (twenty wells) from five selected alluvial fans. The study confirms that the different isotopic signatures characterizing rain and river water from this area can be exploited for preliminary characterization of their significance on groundwater recharge. These results lay the foundations for the further use of a suite of environmental tracers (in which a primary role is that of water stable isotopes) at the event-scale (i.e., that of rainfall and/or flood) for eventually estimating the effective quota of recharge linked to precipitation and surface water.
Highlights
Basin aquifers worldwide are located in the vicinity of mountain chains and are usually made up of porous materials
Italian Apennines are likely to be mainly recharged by precipitations infiltrating in their apical areas
Wells located in the apical part of the alluvial fans from the other two rivers (Enza and Secchia) have shown a more complex behaviour suggesting either precipitations and river dispersions are currently participating in the aquifer recharge
Summary
Basin aquifers worldwide are located in the vicinity of mountain chains and are usually made up of porous materials. Being located in lowland areas, i.e., where urbanization phenomena and population are concentrated, they are often intensively exploited for water supply [1]. It is well recognized that a remarkable portion of their recharge comes from the neighbouring mountain chains. Due to the orographic effect, mountain areas are usually characterized by greater amounts of precipitation that are subsequently released to the lowlands representing, for the latter, an additional water quota with respect to the only zenithal precipitation for their recharge. All the processes acting to recharge the basin aquifer can be split into two sub-processes, whose intensities may vary in time and space even considering the same basin aquifer [2]. The first sub-process is represented by the sub-surface flow from the adjacent mountains (hereafter called Mountain-Block Recharge, MBR), Water 2020, 12, 1561; doi:10.3390/w12061561 www.mdpi.com/journal/water
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