A parsimonious model for springs discharge reconstruction and forecast for drought management: Lessons from a case study in Central Italy

Karst springs located in Central Apennine ridge (Central Italy), in the Tiber River basin. The assessment of water availability is a key issue in a water supply system because of increasing drought and water scarcity events. Analysing and predicting the dynamic behaviour of groundwater resources is challenging to conceptualize and model, especially in poorly-monitored systems. A parsimonious model based on linear regression between the monthly spring discharge time series and Standardized Precipitation Index is proposed. The model is conceived for management purposes and suitable for users with a limited background in modelling techniques, who can take advantage from an initial knowledge of the aquifers hydrological regime. The model developed for long-term monitored springs is used to reconstruct the historical groundwater hydrographs and to make predictions for poorly-monitored springs with similar properties, exploiting the “similarity principle”. Results highlight the notable performance of this approach, which represents a useful tool for overcoming the limitations in spring discharge monitoring networks. Moreover, the tool is used to test forecast performance enabling water managers to develop a monthly early-warning system fostering a sustainable water resource exploitation and limiting the critical issues of the water supply system, especially during drought periods. Results are discussed from the perspective of the water utilities entrusted to manage their resources in the study region. • Standardized Precipitation Index is used as a proxy of natural monthly springs discharge in a linear regression model. • The hydrograph of poorly-monitored springs is better reconstructed exploiting the “similarity principle”. • A supervised application of the model enables to effectively forecast the onset of hydrological drought events. • The model represents an effective early-warning system useful in water resource management.