Drought simulation with hydrological modelling in the Cuneo district (Italy)

Drought is one of the severest natural hazards that seriously threatens sustainable water resource management, agriculture, and socioeconomic sectors within a changing climate context. This study investigates drought simulation through rainfall-runoff modelling over a 60-year period within the Cuneo district of Italy. The research herein discussed leverages the TUW model lumped conceptual rainfall-runoff model with semi-distributed operational capability. Similar in structure to the widely used Hydrologiska Byråns Vattenbalansavdelning (HBV) model, the TUW model operates on a daily timestep for both input and output data specific to each catchment, incorporating key routines for snow accumulation, snowmelt, soil moisture storage, and streamflow generation. In the district of Cuneo, some catchments can provide detailed discharge data, which forms the comprehensive basis for model calibration in this research, first using KGE and then by log-transformed KGE. Special attention will be dedicated to an accurate representation during low-flow events within drought periods to be able to simulate realistic water availability during the most critical periods. The simulated monthly discharges will be used for the validation of the model performance. Apart from model calibration and validation, SRI has been used in the study to undertake advanced drought analysis that can present a precise characterization of the drought occurrences in the region. The discharge data from the observation and simulation are carefully compared with an emphasis on low-flow events that may signify a drought. The complex relationships among land characteristics, including soil type and vegetation cover, and climate variables such as precipitation and temperature, for determining the severity and duration of hydrological droughts are also dealt with in the study. From these findings, it can be seen that for the majority of catchments, very good model efficiencies were achieved upon calibration of the TUW model. A comparison of the simulated and observed discharge data reveals good agreement, in particular for the critical low-flow periods, which is also confirmed by the Pareto coefficient as a goodness-of-fit measure. The drought analysis provides very important information on the duration, intensity, and severity of drought events, adding substantial knowledge to water resources management and drought mitigation. The contribution of this study would add significantly to drought dynamics for the region of Cuneo, whereas future works will make refinement of hydrological modelling techniques and explore various drought projections according to different climate change scenarios.