| Abstract | The present communication describes several regional-scale
modelling experiences involving the carbonatic aquifer of Mt
Coscerno and the alluvial aquifer of Petrignano d'Assisi. The aim is
to highlight the principal differences and similarities in the application
of mathematical models to carbonatic aquifers in mountain areas
and to alluvial type aquifers resulting principally from the different
availability of data. In the first case the hydrogeological balance,
determined by field measurements, is usually known while direct
observation of the piezometric surface is difficult owing to its
extreme depth; in the second case, the piezometric surface is determined
by measurement of piezometric level in wells although the
aquifer balance is generally known only through indirect estimates of
the effective infiltration and any other ancillary contributions
(exchanges with watercourses, infiltration from boundaries, etc). The
determination of the hydrodynamic parameters, wherever this is possible
by means of pumping tests, in any case has only a local meaning
and is influenced by the scale factor.
This results in different approaches both to the processing of the
conceptual model and in the phase of calibrating the numerical
model: in simulating carbonatic aquifers the calibration target consists
of the balance, as constrained by the geometry of the system
within a reasonable range of hydraulic heads and transmissivity values.
In the case of alluvial aquifers the simulation target consists of
the piezometric heads within a reasonable estimate of the balance and
of the range of the hydrodynamic parameters.
The aim is to demonstrate that, despite the difference in approach
to the reconstruction of the conceptual model, in one case based
essentially on the knowledge of the balance, and in the other of the
piezometric heads, the validity of the numerical models described is
in our view comparable. |
| Text | 67852 2009 10.4408/IJEGE.2009 01.O 10 FROM A HYDROSTRUCTURAL ANALYSIS TO THE MATHEMATICAL MODELLING OF REGIONAL AQUIFERS PREZIOSI E., ROMANO E. Istituto di Ricerca sulleAcque IRSA CNR Area della Ricerca di Roma 1 Via Salaria, km 29.300 CP10 00016 Monterotondo Roma Italy The present communication describes several regional scale modelling experiences involving the carbonatic aquifer of Mt Coscerno and the alluvial aquifer of Petrignano d Assisi. The aim is to highlight the principal differences and similarities in the application of mathematical models to carbonatic aquifers in mountain areas and to alluvial type aquifers resulting principally from the different availability of data. In the first case the hydrogeological balance, determined by field measurements, is usually known while direct observation of the piezometric surface is difficult owing to its extreme depth; in the second case, the piezometric surface is determined by measurement of piezometric level in wells although the aquifer balance is generally known only through indirect estimates of the effective infiltration and any other ancillary contributions exchanges with watercourses, infiltration from boundaries, etc . The determination of the hydrodynamic parameters, wherever this is possible by means of pumping tests, in any case has only a local meaning and is influenced by the scale factor. This results in different approaches both to the processing of the conceptual model and in the phase of calibrating the numerical model in simulating carbonatic aquifers the calibration target consists of the balance, as constrained by the geometry of the system within a reasonable range of hydraulic heads and transmissivity values. In the case of alluvial aquifers the simulation target consists of the piezometric heads within a reasonable estimate of the balance and of the range of the hydrodynamic parameters. The aim is to demonstrate that, despite the difference in approach to the reconstruction of the conceptual model, in one case based essentially on the knowledge of the balance, and in the other of the piezometric heads, the validity of the numerical models described is in our view comparable. In questa comunicazione si descrivono alcune esperienze di modellazione alla scala regionale, relative all acquifero carbonatico di Monte Coscerno e all acquifero alluvionale di Petrignano d Assisi. L obiettivo e di evidenziare le principali differenze e analogie nell applicazione della modellazione matematica agli acquiferi carbonatici in aree montuose e agli acquiferi di tipo alluvionale, principalmente a causa della diversa reperibilita dei dati. Nel primo caso e generalmente noto il bilancio idrogeologico, determinato mediante misure di campo, mentre e difficile l osservazione diretta della superficie piezometrica a causa della sua notevole profondita; nel secondo caso la superficie piezometrica viene determinata a partire dalla misura dei livelli nei pozzi, ma non e generalmente noto il bilancio dell acquifero se non attraverso stime indirette dell infiltrazione efficace e degli eventuali altri apporti laterali, degli scambi con i corsi d acqua, eccetera. La determinazione dei parametri idrodinamici, laddove possibile mediante prove di pozzo, ha comunque valore locale ed e influenzata dal fattore di scala. Questo determina approcci diversi sia nell elaborazione del modello concettuale che nella fase di calibrazione del modello numerico per la simulazione di acquiferi carbonatici il target della calibrazione e il bilancio, vincolato dalla geometria del sistema nell ambito di un ragionevole range di potenziali idraulici e di trasmissivita. Il target della simulazione negli acquiferi alluvionali e invece il campo dei potenziali, vincolato dalla geometria del sistema nell ambito di una stima ragionevole del bilancio e di un ordine di grandezza dei parametri idrodinamici. Si vuole mostrare come, nonostante la diversita dell approccio nella ricostruzione del modello concettuale, basato in un caso essenzialmente sulla conoscenza del bilancio, nell altro del campo dei potenziali, la validita dei modelli numerici descritti sia a nostro avviso confrontabile. 1 http //www.ijege.uniroma1.it/rivista/ijege 09/ijege 09 volume 01/ FROM A HYDROSTRUCTURAL ANALYSIS TO THE MATHEMATICAL MODELLING OF REGIONAL AQUIFERS ijege_09_01_preziosi_romano.pdf Articolo in rivista Centro Stampa d Ateneo 1825 6635 Italian journal of engineering geology and environment Testo stamp. Italian journal of engineering geology and environment Testo stamp. Ital. j. eng. geol. environ. Testo stamp. Italian journal of engineering geology and environment. Testo stamp. elisabetta.preziosi PREZIOSI ELISABETTA emanuele.romano ROMANO EMANUELE TA.P02.009.002 Effetti dei cambiamenti climatici sulla componente terrestre del ciclo idrologico |
