Monitoring and Modelling Interactions between the Montagna dei Fiori Aquifer and the Castellano Stream (Central Apennines, Italy)

Alberto Tazioli,Torquato Nanni,Micòl Mastrocicco,Nicolò Colombani,Stefano Palpacelli

doi:10.3390/w12040973

Abstract

Groundwater is the most used water resource around the world, but due to population growth and climate change the alluvial lowland aquifers are often polluted and over-exploited. Thus, more and more frequently water managers need to shift their attention to mountain regions to identify groundwater resources for drinking purposes. This study presents a monitoring and modelling approach that allowed to quantify the inflow from the “Montagna dei Fiori” fractured aquifer to the Castellano stream. Continuous monitoring of flow discharge and temperature during an entire hydrological year (2018–2019) at two monitoring stations along the stream allowed to discriminate between the baseflow (on average, 0.891 m3/s) and the run-off (on average, 0.148 m3/s) components. A hydrogeological basin-wide numerical flow model (using MODFLOW-2005) was set up using information from hydrogeological and geomechanical surveys. The model was calibrated using the daily baseflow observations made in the Castellano stream (R2 = 0.75). The calibrated model allowed to quantify groundwater/surface water interactions. After an automated sensitivity analysis (using MODFLOW-2000), the recharge was found to be the most uncertain parameter, followed by the hydraulic conductivity zonation. This methodology could be applied in other mountain regions where groundwater monitoring networks are usually lacking to improve water resources management.

Highlights

Continuous monitoring of water fluxes and temperatures in stream reaches fed by groundwater are often key points to understanding water flux exchange from groundwater/surface water interactions [1,2]
This paper presents a methodological approach to quantify groundwater/surface water interactions using information from hydrogeological and geomechanical surveys, borehole logs, pumping tests and continuous monitoring of flow discharge and temperature
The MODFLOW-2005 numerical code [25] was used to create a numerical flow model of the whole hydrogeological basin of the “Montagna dei Fiori”, which is a fractured aquifer that covers an area of about 50 km2

Summary

Introduction

Continuous monitoring of water fluxes and temperatures in stream reaches fed by groundwater are often key points to understanding water flux exchange from groundwater/surface water interactions [1,2]. Stream flow and temperature continuous monitoring are often a key point to understand water fluxes exchanges from and to aquifers in lowland river catchments [3,4,5], or by using remote sensing where monitoring well networks are scarce or absent [6]. In recent literature there are many examples of surface waters/groundwater exchange fluxes determined by for example streambed temperature data, piezometric head data and simple 1D models or analytical solutions for flux calculation. Numerous models have been successfully developed for use in porous aquifers [8,9], their application in fractured aquifers is more problematic.

Methods

Results

Conclusion