The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Elisa Brussolo(1), Brunella Raco(2), Matia Menichini(2), Marco Doveri(2), Andrea Irace(2), Giulio Masetti(2), Antonello Provenzale(2) [email protected] (1) Centro Ricerche SMAT (Società Metropolitana Acque Torino) (2) Consiglio Nazionale delle Ricerche-Istituto di Geoscienze e Georisorse Globally, groundwater provides (WWDR, 2015; FAO, 2010; WBCSD, 2006): drinking water to more than 50% of the population 43% of the irrigation water 40% of the industrial water In Europe, the groundwater exploitation provides domestic water to the 70% of the population [email protected] average (Martinez et al., 2008) The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Aquifer Systems involved in the NEXTDATA project [email protected] The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Aquifer Systems involved in the NEXTDATA project PS.01 - Poster Session 1 TODAY, 5:30 PM - 6:30 PM POSTER PS.01/04 THIS PRESENTATION [email protected] The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Aquifer Systems involved in the NEXTDATA project [email protected] The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry GENERAL APPROACH ADOPTED FOR THE STUDIED GROUNDWATER SYSTEMS - Collection of data and information concerning, geology, hydrology, hydrogeology, water chemistry, water isotopes, etc.. mainly from publications and available database, plus a few new data; - Elaboration of the aquifers conceptual model by involving and comparing physical and chemical features; - Trends analysis on the continuous monitoring data, referring to both quantity and quality of groundwater; - Development of numerical models throughout either empirical or physically-based approach, accordingly the [email protected] conditions of aquifers and the availability of data and information. The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry The foothill zone of the Piedmont Alps Simplified geological map of the western Piedmont Simplified geological 3D-scheme (modified from De Luca and Ossella, 2014) The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry The foothill zone of the Piedmont Alps Simplified geological map of the western Piedmont Simplified geological 3D-scheme (modified from De Luca and Ossella, 2014) main aquifers exploited for drinking, agricultural, industrial purposes FROM MONO-LAYER (unconfined or semi-confined), TO MULTI-LAYER The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Basin’s Rainfall (average water year [AWY] 2000-2015) 800÷1300 mm Runoff Coefficient-RC (AWY 2000-2015) 0.90 0.88 Mt. Ciamarella (3676 m) 0.67 0.78 0.58 0.69 0.70 0.65 in mountain basins 0.67 Torino (250 m) 0.50 RC = or > 0.7 0.76 0.34 0.24 Low water infiltration 0.55 0.43 The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Piezometric map (data source: www.webgis.arpa.piemonte.it) - the Po River acts as the final drainage of the aquifer system - underground transfers of water from mountain zones, as well as river seepage towards groundwater - in some sectors, main tributaries act as drainage of the aquifer The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry 0 100 0 100 CALUSO POIRINO Groundwater Chemistry POIRINO 25 75 Shallow wells 25 75 (raw data from ARPAP database) POIRINO 50 50 50 50 POIRINO CARMAGNOLA POIRINO RIVAROLO CANAVESE RONDISSONE POIRINO POIRINO POIRINO ‘’ ‘’ 75 25 75 25 FROSSASCO AIRASCA FAVRIA POIRINO MONTANARO FAVRIA ORBASSANO GIVOLETTO CALUSO 100 0 100 0 COLLEGNO 0 25 50 75 100 0 25 50 75 100 HCO3 Ca 0 100 0 100 25 75 Deep wells 25 75 50 50 50 50 AVIGLIANA TORINO CIRIE' CIRIE' 75 25 75 CANDIOLO 25 VOLPIANO CIRIE' LA CASSA DRUENTO COLLEGNO SAN GILLIO 100 0 100 0 VIGONE 0 25 50 75 100 0 25 50 75 100 HCO Ca Torino 3 - water are mainly of the Ca(Mg)-HCO3 type and have a relatively low salinity in both shallow and deep wells congruence with lithologies; - shallow wells show slightly wider range and variability over time in terms of concentrations phreatic flow and its possible connection with rivers; - major stability and lower salinity in deep wells “confined” nature of the aquifer system at depth. Nevertheless, local chemical features suggest a possible exchange with the phreatic zone. The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Local evidence of the multi-layer character of the system Physical-chemical vertical log and sampling performed at different depths within multi-screened piezometers δ18O (vs. VS-SMOW) - 9.7‰ - 9.5‰ - 10.0‰ Significant differences with depth in terms of EC, T and water isotope signature (3 groundwater inputs) The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Schematic model of groundwater flow-paths, inputs and outputs The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry 3D numerical model of groundwater flow (steady-state transient) Implementation of the model Active domain and Hydrologic boundary conditions spatial discretization model domain 2 (≈350 km ) A A’ Torino Modflow FD code (USGS) GUI: Visual Modflow Hydrodynamic parameters A A’ Hydrologic sink and source terms Recharge Well pumping rate Starting from the Yearly Water Balance of the Piedmont Alpine Zone (Brussolo et al., 2018 – in Drinking water about 77 Mm3/yr the poster session of this conference): For the Steady State model, 600 mm as mean value of Industrial well about 66 Mm3/yr “yearly actual renewable water resource” (GW+SW) was translated in recharge by using Agricultural purpose about 11.5 Mm3/yr infiltration coefficient (IC) - Urban area 150 mm (I.C. 25%); Rural area 350 mm (I.C. 60%); Domestic wells about 0.05 Mm3/yr For the Transient model, monthly values from Jan. 2011 to Dec. 2015 were implemented. The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry 3D numerical model of groundwater flow May 2015 TOTAL Mass Balance Model Calibration and Result Storage (transient model) Recharge River CH Well GHB The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry 3D numerical model of groundwater flow Model Calibration and Result The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Trend analysis of time series of piezometric level and chemical concentration Network of piezometers Network of wells for chemical monitoring ‘’ ‘’ Torino Torino ARPAP The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Piezometric level (m a.s.l.) Trend analysis of of analysis monthly Torino piezometric levels piezometric The foothill aquifer system ofthePiedmontThe hydrogeology foothill and groundwateraquifer system Alpine chemistry zone:geology, Piezometric level (m a.s.l.) Yearly rainfall (average among basins) among some (average rainfall Yearly Trend analysis of monthly piezometric levels Similar behavior of piezometric levels across the area Torino Sharp increase in 2008/2009 (of the order of 3m) as response to a rainier period. Over the 2009-2017 period, most piezometers shows a significant trend of GW decreasing Confidence level of the trend 95% to 99% The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Trend analysis of chemical data (zones with higher concentrations) Nitrate Chloride II semester 2016 II semester 2016 Torino Torino 0 10000 20000 30000 40000 300 218 257 207 234 258 244 170 191 Maps elaborated by means of Lognormal Kriging 200 107 estimator, after the study of the experimental Variogram : NO3_mg_l 100 variogram and the cross-validation 3 0 0 10000 20000 30000 40000 Distance (m) The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Trend analysis (Mann-Kandall) of chemical data (zones with higher concentrations) 118 piezometer A piezometer B 67 2009-2016 2011-2017 P-value 0.000 Nitrate 108 P-value 0.022 62 Regr. Slope -5.1 Regr. Slope -2.6 98 57 (mg/L) 3 88 NO3 (mg/L) 52 NO Insufficient statistical Insufficient statistical Torino 78 evidence 47 evidence B A 68 42 58 2000 2003 2006 2009 2012 2015 2018 37 2004 2006 2008 2010 2012 2014 2016 50 2010-2016 piezometer A piezometer B 20 P-value 0.000 46 Regr. Slope -0.5 2009-2016 Chloride 42 P-value 0.000 18 Regr. Slope -2.9 38 P-value 0.024 Regr. Slope + 0.37 16 Cl (mg/L) Cl (mg/L) 34 Insufficient statistical evidence Torino 30 14 B 26 A 22 12 2000 2003 2006 2009 2012 2015 2018 2004 2006 2008 2010 2012 2014 2016 The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Trend analysis of chemical data (zones with higher concentrations) 118 piezometer A piezometer B 67 Nitrate 108 62 98 57 (mg/L) 3 88 NO3 (mg/L) 52 NO Torino 78 piezometic level47 B A 68 42 58 2000 2003 2006 2009 2012 2015 2018 37 2004 2006 2008 2010 2012 2014 2016 Possible mobilization of salinity and nutrient 50 2011 2009 piezometer A 2010 piezometer B accumulated in unsaturated zone 20 46 Yearly rainfall Chloride 42 18 38 16 Cl (mg/L) Cl (mg/L) 34 Torino 30 14 B 26 A 22 12 2000 2003 2006 2009 2012 2015 2018 2004 2006 2008 2010 2012 2014 2016 The foothill aquifer system of the Piedmont Alpine zone: geology, hydrogeology and groundwater chemistry Main Conclusions - This foothill aquifer system consists of a multilayer that has a phreatic aquifer overlying a succession of impermeable and permeable layers.