Ador-Solid-Set: A coupled simulation model for commercial solid-set irrigated fields

Abstract

The last five decades have seen strong developments in irrigation modeling. In solid-set sprinkler irrigation, models have generally been applied to a few sprinklers in a regular arrangement, making them representative of a sector or a field. In this research, the Ador-Solid-Set model for whole-field solid-set sprinkler irrigation is presented, validated and applied to simulate an irrigation event in two fields: CA (10.2 ha) and ZA (24.5 ha), equipped with 12 and 26 sectors, respectively. The model couples pipeline hydraulics (EPANET), sprinkler ballistics and irrigation scheduling at execution time. Field experiments were used to validate the ballistic model in a solid-set combining full- and partial-circle sprinklers. Observed and simulated irrigation depths and coefficients of uniformity showed determination coefficients of 0.73*** and 0.89***, respectively. Optimization was used to estimate pipeline roughness based on pairs of pressure measurements (at the inlet and specific sprinklers): 26 pairs in CA and 58 pairs in ZA. Roughness parameters were estimated for the main pipeline, each sector and the sprinkler risers: 14 parameters in CA and 28 in ZA. More than a million hydraulic simulations were required to estimate roughness in each field. Maps were produced for applied water in CA and ZA following a sequential irrigation of their sectors lasting for 24 hours. The model produced whole-field coefficients of uniformity of 80.2 in CA and 80.9 in ZA. Finally, Ador-Solid-Set quantified the volume of drift outside the field (2.4 and 1.5% of the applied water in CA and ZA, respectively). This additional drift can be added to the wind drift and evaporation losses obtained from empirical equations, in a process that requires further analysis. Research efforts are also needed to enhance the current model capabilities and address the challenges related to water quantity and quality in sprinkler solid-sets.

Keywords

• Irrigation uniformity
• Irrigation scheduling
• Pipeline roughness
• Ballistics