Hydrogeological characterization of peculiar Apenninic springs

Abstract

In the northern Apennines of Italy, springs are quite widespread over the slopes. Due to the outcropping of low-permeability geologic units, they are generally characterized by low-yield capacities and high discharge variability during the hydrologic year. In addition, low-flow periods (discharge lower than 1 Ls -1 ) reflect rainfall and snowmelt distribution and generally occur in summer seasons. These features strongly condition the management for water-supply purposes, making it particularly complex. The "Mulino delle Vene" springs (420 m a.s.l., Reggio Emilia Province, Italy) are one of the largest in the Apennines for mean annual discharge and dynamic storage and are considered as the main water resource in the area. They flow out from several joints and fractures at the bottom of an arenite rock mass outcrop in the vicinity of the Tresinaro River. To date, these springs have not yet been exploited, as the knowledge about the hydrogeological characteristics of the aquifer and their hydrological behaviour is not fully achieved. This study aims to describe the recharge processes and to define the hydrogeological boundaries of the aquifer. It is based on river and spring discharge monitoring and groundwater balance assessment carried out during the period 2012-2013. Results confirm the effectiveness of the approach, as it allowed the total aliquot of discharge of the springs to be assessed. Moreover, by comparing the observed discharge volume with the one calculated with the groundwater balance, the aquifer has been identified with the arenite slab (mean altitude of 580 m a.s.l.), extended about 5.5 km 2 and located 1 km west of the monitored springs.

Numerical Modelling of the Mulino Delle Vene Aquifer (Northern Italy) as a Tool for Predicting the Hydrogeological System Behavior under Different Recharge Conditions

“…), where it joins the river Secchia (tributary of the Po River). The Tresinaro stream hydrological catchment covers approximately an area of 147 km 2 , while the recharge area of the aquifer (5.5 km 2 , mean altitude of 620 m a.s.l., [18]; Figure 1) extends across a gentle slope in a non-urbanized area. In particular, with reference to 2008 data [19], the agricultural lands are 41% of the springs recharge area, the forest is 58%, and the urban lands are 1%.…”

“…The average annual temperature is about 12.7 • C. The hottest month is July with an average temperature about 22.7 • C, while the coldest month is January with an average of 3.3 • C. The average effective rainfall (i.e., the part of precipitation that remains at the ground surface after evaporation and transpiration processes and is thus available for subsequent infiltration and runoff) has been assessed on a daily time scale as the difference between the rainfall and the computed evapotranspiration with the Hargreaves formula [26], as suggested by Allen et al [27]. This assumption is acceptable since the lack of runoff in the streambeds during the whole year suggests that almost all meteoric water can be considered as recharging the aquifer [18]. Moreover, the amount of abstractions is negligible since the area is sparsely urbanized and no industrial facilities can be found.…”

“…These springs represent the final source point of the hydrogeological system. Based on Cervi et al [18], it is possible to affirm that the main aquifer feeding the springs is the fractured sandstones unit (PAT4). The size of the recharge area is approximately 5.5 km 2 and it extends along a gentle slope in a non-urbanized area [22].…”

“…3 . Hence, they can be considered the main water resources in the area [16,18,22]. These springs have been the object of comprehensive study and analysis since 2013 [22].…”

“…Following the same method used by Cervi et al [18], the total outflow from the springs was computed from the measured outflow in one weir, which was monitored from 2013 to 2016. Figure 4 displays the average daily discharge and the observed daily rainfall at the Carpineti weather station.…”