12 Jul 2022
 | 12 Jul 2022

Resolving the water budget of a complex carbonate basin in Central Italy with parsimonious modelling solutions

Shima Azimi, Christian Massari, Giuseppe Formetta, Silvia Barbetta, Alberto Tazioli, Davide Fronzi, Sara Modanesi, Angelica Tarpanelli, and Riccardo Rigon

Abstract. Placed at the center of the Mediterranean, the Apennines chains provide a critical water supply for people living in the Italian Peninsula. Yet, the quantification of water resources in this region is challenging given that the different components of the water cycles (i.e., snowmelt, evapotranspiration, and subsurface water recharge) are highly variable in space and time due to the specificity of the climate, the reforestation trend, and the complex landscapes and geology. In this study, we investigated the challenging hydrological river regime of a complex carbonate basin with significant external (and partially karst) groundwater contribution – the Upper Nera basin – affected by recent important seismic sequences.

When dealing with such type of basins, the generic approach to delineate the basin boundaries based on the geomorphology of the area can lead to questionable results potentially yielding significant water budget imbalances. Therefore, both (hydro)geological and hydrological features have to be considered for understanding the challenging hydrological behavior of these basins.

Here we proposed a specific analysis of precipitation-runoff time series corroborated with hydro-geological survey to obtain information on the basin response time and the real contribution area of the basin. Then, we integrated this information within the structure of a hydrological model (i.e., the Geoframe modelling system) by using a parsimonious type of approach to improve the description of the different components of the water balance with a specific focus on external groundwater recharge. We validated the model against in situ discharge observations and with remote sensing information of evapotranspiration and snow. Since these two variables (snow cover and evapotranspiration) play the crucial role in correct estimation of water balance in the basin, in this study we additionally focused on that.

We show that the model (tested with several hydrological signatures and a new conceptual evaluation based on an empirical probability function) performs relatively well in reproducing the different water balance components (including remotely sensed evapotranspiration and snow) and that the upper river basin is significantly impacted by carbonate rock river discharge (i.e., up to 85 % in proportion to the total discharge for some stations) coming from outside the geomorphological boundary of the basin. Yet, the groundwater recharge effects on the river, gradually attenuates at the outlet of the basin (Visso station).

Shima Azimi et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-340', Anonymous Referee #1, 04 Nov 2022
    • AC1: 'Reply on RC1', Riccardo Rigon, 26 Mar 2023
    • AC2: 'Reply on RC1', Riccardo Rigon, 26 Mar 2023
  • RC2: 'Comment on egusphere-2022-340', Anonymous Referee #2, 31 Jan 2023
    • AC3: 'Reply on RC2', Riccardo Rigon, 26 Mar 2023

Shima Azimi et al.


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Short summary
We analyzed the water budget of nested karst catchments with simple methods and modelling. Whilst karst pathways are not elusive, we exploit techniques to have information from the available data of precipitation and discharge which result in a reliable determination of the response lag-time. We also modelled snow cover dynamics and evapotranspiration obtaining a parsimonious account of the water budget of the basin and its subbasins. Data, models and workflows has been made available.