Accounting for Modelled Irrigation in the Long-Term Water Budget Analysis of an Alpine Anthropized Basin.

Irrigation is an essential component of food systems. Worldwide, 40% of global food production comes from irrigated croplands despite the latter accounting for 20% of total cropland. With limited available locations to grow crops, an increasing population and a changing climate, irrigation is a crucial component to help meet a rising demand on food production systems. It is also a process with increasing consideration in current hydrological model developments.

Building on a previously flexible and open-source hydrological digital twin for the Adige River basin (~11000 km²), located in the north-east of Italy, at high temporal (daily) and spatial resolution (5km²), a novel irrigation modelling component is implemented for the study area. Irrigation water is crucial to the economy of the region, for fruit productions (vineyards and apple) and necessary to be included into water budget quantification to accurately represent hydrological processes.

The implementation includes water demand assessment through soil moisture and evapotranspiration, while accounting for the different type of crops and specific water needs. Irrigation is activated when volumetric soil water content (dependent on saturation and wilting points) falls below a fixed threshold. The flexibility of the digital twin framework allows us to quantify the effect of various threshold levels on irrigation estimates but also in terms of water processes. Water availability is considered through 2 scenarios (limited where water is taken from another component of the model or unlimited). The model accounts for daily limits in irrigation as well as efficiency.

Results show the different range with regards to irrigation quantities and hydrological processes dependent on the different thresholds and limitation formulae retained, outlining the importance of diverse possibilities in the implementation of irrigation.

Furthermore, integrating irrigation into the digital twin has been shown to improve the river discharge simulations under the limited irrigation scenario when compared with measured data and actual evapotranspiration. This enhancement is particularly evident in areas where irrigation represents an important input of the hydrological cycle.

This study can be useful to regional water managers, policy makers, and stakeholders, especially in regions where conflicts are strife between the different usages (domestic, agricultural, industrial/ hydropower) and particularly in a changing climate.

 

The work is supported by the project Fondo per il Programma Nazionale di Ricerca e Progetti di Rilevante Interesse Nazionale (PRIN) Control-based Optimization of the AnthropogeniC Hydrological cycle for a sustainable WATer management (COACH-WAT, CODE 2022FXJ3NN CUP E53D23004390001).

Selected references:

Morlot, M., Rigon, R., & Formetta, G. (2024). Hydrological digital twin model of a large anthropized italian alpine catchment: The Adige river basin. Journal of Hydrology, 629, 130587