Advancing hydrological modeling in small watersheds: the fiumarella case study (southern Italy)

The hydrological response of small basins remains complex and challenging  to quantify in an accurate way, particularly during extreme events such as floods as well as in the context of sustainable water resources management (Sellami et al., 2016). The application of hydrological models at basin scale offers a promising solution to this challenge by providing valuable tools for water resources management, enabling the analysis of past and current basin conditions as well as the evaluation of the implications of management decisions and imposed changes. In this study, the distributed hydrological model DREAM (Manfreda et al., 2005; Perrini et al., 2024), which incorporates Dunnian and Hortonian mechanisms, was applied to simulate flood events in the Fiumarella di Corleto basin (32.5 km²) and its sub-basin (0.65 km²) in the Italian region of Basilicata. Simulations were conducted for flood events occurring over a 20-year period (2002–2022). These simulations were based on a detailed hydrological and geomorphological characterization of the study area, integrating a hydro-meteorological dataset and initial soil moisture conditions derived from monitoring instruments and a geographical database (Dal Sasso et al., 2023) . Significant flood events were selected for model parameter optimization,  due to their representativeness, allowing for the verification of the model’s performance, ensuring its ability to accurately reproduce hydrological behavior as well as for belonging to a dataset characterized by complete hydrological information. The results show that the hydrological model, with the Hortonian runoff mechanism, outperforms in capturing the basin’s immediate response to rainfall events. Preliminary results revealed a satisfactory match between simulated and observed data, as evidenced by the Nash-Sutcliffe efficiency coefficient ranging from 0.52 to 0.73 and the Kling-Gupta efficiency coefficient between 0.56 and 0.75. While errors in simulated and observed peak outflows varied, ranging from acceptable (2–3%) to more significant (up to 20%), the overall performance metrics indicate reliable alignment.  These findings underscore the model’s capability to accurately reproduce flood processes, confirming its reliability for simulating extreme hydrological events and supporting its application in watershed management and flood risk mitigation.

DISCLAIMERS

The present research has been carried out within the RETURN Extended Partnership and received funding from the European Union Next-Generation EU (National Recovery and Resilience Plan - NRRP, Mission 4, Component 2, Investment 1.3 - D.D. 1243 2/8/2022, PE0000005).

This abstract is part of the project NODES which has received fundining from the MUR-M4C2 1.5 of PNRR funded by the European Union - NextGenerationEU (Grant agreement no. ECS00000036).