Promoting precision surface irrigation through hydrodynamic modelling and microtopographic survey

Authors: CARMELINA COSTANZO - University Of Calabria; PIERFRANCO COSTABILE - University Of Calabria; FABIOLA GANGI - University Of Milan; GIUSEPPE ARGIRÒ - University Of Milan; Bautista, Eduardo; CLAUDIO GANDOLFI - University Of Milan; DANIELE MASSERONI - University Of Milan

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2024
Publication Date: 8/1/2024
Citation: Carmelina Costanzo, Pierfranco Costabile, Fabiola Gangi, Giuseppe Argirò, Bautista, E., Claudio Gandolfi, Daniele Masseroni 2024. Promoting precision surface irrigation through hydrodynamic modelling and microtopographic survey. Agricultural Water Management. 301. Article 108950. https://doi.org/https://doi.org/10.1016/j.agwat.2024.108950.
DOI: https://doi.org/10.1016/j.agwat.2024.108950

Interpretive Summary: Surface irrigation modeling tools have been under development for over forty years. They are now commonly used to conduct hydraulic analyses of irrigation systems, with the goal of improving their design and operation. Existing models are based on numerous simplifying assumptions. Consequently, they often cannot reproduce special configurations that are found in the field. A key limitation is the assumption of one-dimensional flow. In border and basin systems, the irrigation stream often travels non-uniformly across the field, mainly due to variations in surface elevation and to the location of the inlet structure. This study presents a two-dimensional modeling system capable of capturing those lateral flow variations. The model uses advanced computational techniques to solve the governing equations. The study compares simulation results assuming one-dimensional flow with those computed with the two-dimensional model. The two-dimensional model produced more conservative estimates of irrigation performance than the one-dimensional model under the conditions of the study. In addition, the two-dimensional model was easily adapted to replicate a cascaded irrigation system, which cannot be handled by the simpler one-dimensional model. This information should be of interest to irrigation researchers and practitioners.

Technical Abstract: Precision irrigation aims to deliver water and nutrients to crops at exactly the right time, in the right place and in the right amount. While surface irrigation is often perceived as less precise, accurate water distribution, wise use of resources and high efficiency can still be achieved with careful land preparation, astute irrigation management and rigorous performance monitoring. In this study, we advocate the innovative concept of Precision Surface Irrigation, centered around three key design and operational principles: (i) well-organized field geometry (and microtopography), (ii) precise control of hydraulic-hydrological variables, and (iii) regular performance evaluation. These pillars are then integrated into a simulation environment capable of capturing the intricacies of surface irrigation dynamics. This new concept has been presented through a field and simulation study conducted in the Padana plain (northern Italy) where one-dimensional and two-dimensional irrigation dynamic modelling (respectively provided by WinSRFR and IrriSurf2D models) were contrasted. Data on boundary geometries, inflow rates, duration of irrigation interventions and microtopography were collected and a spatially distributed assessment of irrigation performance was provided from both models. The results show that the versatility of the two-dimensional modelling approach was able to reproduce well the observed water depths and the phases of water advance and depletion both in time and space within the studied border irrigation strips, even in complex situations where the strips were hydraulically connected. The RMSE between observed and simulated maximum water depth and waterfront advance time was less than 2.1 cm and 1.9 min, respectively. The two-dimensional approach was also able to detect the cross variability of irrigation dynamics, and to provide a spatial assessment of irrigation performance at high resolution. In conclusion, while the one-dimensional hydrodynamic approach to describing the hydraulic behavior of surface irrigation and field-scale irrigation performance remains valid, the two-dimensional approach provides, in our case study and reasonably elsewhere, a valid simulation environment for spatially characterizing irrigation dynamics in the context of Precision Surface Irrigation.