| Title | A conceptual model for a fractured volcanic aquifer to investigate the role of climate variability and water withdrawal on recent changes in water-table and discharge |
| Abstract | The Alcantara River Basin is located in North-Eastern Sicily (Italy), encompassing the north side of
Etna Mountain, the tallest active volcano in Europe. On the right-hand side of the river, the
mountain area is characterized by volcanic rocks with a very high infiltration. Here, precipitation
and snow melting supply a big aquifer whose groundwater springs at the mid/downstream of the
river, mixing with surface water and contributing to feeding the river flow also during the dry
season. In the upstream a maximum of 520 l/s are extracted for municipal use through wells and
an infiltration gallery supplying the Alcantara Aqueduct. In summer 2020 and 2021, the river
suffered a prolonged dry phenomenon in the middle-valley stretch with a serious loss of fish
fauna, due to significant spring depletion along the stream most likely determined by a
meteorological drought. Since this anomaly is of great concern, the need arises to better
understand whether the interaction between the water abstraction to supply the Alcantara
aqueduct and the natural recharge of the aquifer is compatible with maintaining the balance of
aquatic ecosystems in the middle-downstream valley of the Alcantara River also during dry years;
or if the observed changes may also be partly due to other mechanisms, such as illegal or
unaccounted water abstractions or hydrogeological modification due to the volcanic activity. To
this end, in this study, an attempt was made to analyze changes in the groundwater level and in
the interconnection between surface and groundwater by using the widely accepted MODFLOW 6,
a finite-difference numerical model that in principle can provide constraints to reduce uncertainty
and address field activity in data scarce case studies. The model was calibrated in steady state by
comparing simulated and observed water heads as well as the groundwater budget. Then the
simulation was run in transient mode for the period 2014-2021. The model outcome showed a
depletion rate compatible with the one observed during the recent dry summers, thus suggesting
that more sustainable and comprehensive strategies, also including groundwater extraction
regulations, should be implemented to preserve this natural resource for in-stream water use and
ecosystem services. |
| Source | egu 2023, Vienna, 23-28/04/2023 |
| Keywords | Groundwater flow modelEtnagroundwater surface water interaction |
| Year | 2023 |
| Type | Abstract in atti di convegno |
| DOI | 10.5194/egusphere-egu23-14029 |
| Authors | Brunella Bonaccorso, Marco Silipigni, Cristina Di Salvo, Iolanda Borzì, and Elisabetta Preziosi |
| Text | 481641 2023 10.5194/egusphere egu23 14029 Groundwater flow model Etna groundwater surface water interaction A conceptual model for a fractured volcanic aquifer to investigate the role of climate variability and water withdrawal on recent changes in water table and discharge Brunella Bonaccorso, Marco Silipigni, Cristina Di Salvo, Iolanda Borzi, and Elisabetta Preziosi Department of Engineering, University of Messina, Contrada di Dio, Messina, Italy Institute of Environmental Geology and Geoengineering, National Research Council, Area della Ricerca Roma 1, Monterotondo Rome , Italy Water Research Institute, National Research Council, Area della Ricerca Roma 1, Monterotondo Rome , Italy Published version https //doi.org/10.5194/egusphere egu23 14029 egu 2023 Vienna 23 28/04/2023 Internazionale Contributo The Alcantara River Basin is located in North Eastern Sicily Italy , encompassing the north side of Etna Mountain, the tallest active volcano in Europe. On the right hand side of the river, the mountain area is characterized by volcanic rocks with a very high infiltration. Here, precipitation and snow melting supply a big aquifer whose groundwater springs at the mid/downstream of the river, mixing with surface water and contributing to feeding the river flow also during the dry season. In the upstream a maximum of 520 l/s are extracted for municipal use through wells and an infiltration gallery supplying the Alcantara Aqueduct. In summer 2020 and 2021, the river suffered a prolonged dry phenomenon in the middle valley stretch with a serious loss of fish fauna, due to significant spring depletion along the stream most likely determined by a meteorological drought. Since this anomaly is of great concern, the need arises to better understand whether the interaction between the water abstraction to supply the Alcantara aqueduct and the natural recharge of the aquifer is compatible with maintaining the balance of aquatic ecosystems in the middle downstream valley of the Alcantara River also during dry years; or if the observed changes may also be partly due to other mechanisms, such as illegal or unaccounted water abstractions or hydrogeological modification due to the volcanic activity. To this end, in this study, an attempt was made to analyze changes in the groundwater level and in the interconnection between surface and groundwater by using the widely accepted MODFLOW 6, a finite difference numerical model that in principle can provide constraints to reduce uncertainty and address field activity in data scarce case studies. The model was calibrated in steady state by comparing simulated and observed water heads as well as the groundwater budget. Then the simulation was run in transient mode for the period 2014 2021. The model outcome showed a depletion rate compatible with the one observed during the recent dry summers, thus suggesting that more sustainable and comprehensive strategies, also including groundwater extraction regulations, should be implemented to preserve this natural resource for in stream water use and ecosystem services. Abstract in atti di convegno EGU General Assembly Conference Abstracts EGU General Assembly Conference Abstracts elisabetta.preziosi PREZIOSI ELISABETTA cristina.disalvo DI SALVO CRISTINA |
