Dynamic model for water application using centre pivot irrigation

Abstract

The application pattern for single, stationary spray sprinklers exposed to the wind was modelled to simulate water application in a centre pivot irrigated field. In the model, a dynamic square grid of cells for water application and a static square grid of cells for water collection were defined. The dynamic grid contained the information on the water application pattern of an isolated spray sprinkler, and this followed the motion of the centre pivot lateral. The static grid represented the entire the field, and received water from the dynamic grid at fixed time intervals. Model outputs included the applied water distribution pattern and measures of irrigation uniformity (radial, travelling path and global). A series of experiments using pivoted and single spray sprinklers were conducted simultaneously. The results from the model compared well with field observations. The resulting root mean square errors for the Heermann and Hein uniformity coefficient and the average applied water depth were 0.02 % and 0.08 mm, respectively. Model simulations were carried out to illustrate the effect of wind on irrigation uniformity.

Characteristics of water and droplet size distribution from fluidic sprinklers

“…The sprinkler pattern model has been selected as the basis of the decision support system TRAVGUN, which was created by Richards and Weatherhead (1993) and modified by Al-Naeem (1993). A third-order polynomial was used to describe the radial, and Delirhasannia et al (2010) developed a model to simulate the application of water in a centre-pivot-irrigated field. Li et al (1995) proposed an empirical model to fit the drop diameter distribution curve.…”

Simulating water distribution patterns for fixed spray plate sprinkler using the ballistic theory

“…Current center-pivot models are based on the overlapping of experimental sprinkler application pattern (Omary & Sumner, 2001;Delirhasannia et al, 2010). Based on semi-empirical considerations and using a combination of beta functions (free from any ballistic consideration), and developed a model to simulate the application pattern of a single spray sprinkler, and to describe its performance in both windy and no-wind conditions.…”

Effect of the start–stop cycle of center-pivot towers on irrigation performance: Experiments and simulations

“…Omary and Sumner (2001) presented a model that only accounted for the intermittent movement of the outermost tower, assuming perfect alignment between all towers (hydraulic drive machine). Delirhasannia et al (2010) modified the model presented by Omary and Sumner (2001) to include the effect of wind speed and direction on sprinkler water distribution patterns, overlapping the experimental application patterns of isolated sprinklers.…”

“…The grids representing the sprinklers were computed using ballistic theory as reported inOuazza et al (2013). Other authors have used experimentally determined water distribution grids(Delirhasannia et al, 2010) or statistically defined water distribution patterns(Gat and Molle, 2000).The advantage of the method used in this paper is that model parameters can be extrapolated to non-evaluated nozzle diameters (within the experimental range), wind speeds (from 0 to 8 m s -1 ) and working pressures (from 15 to 20 psi).The effect of grid size on center-pivot irrigation performance was analysed. Five square grid sizes (from 0.5 m to 0.03125 m in side) defining the nozzle water distribution pattern of each sprinkler were simulated with the ballistic model presented inOuazaa et al (2013).…”