Asymmetric Wetted Sector Angle in Water Distribution of Traveling Gun Irrigation Systems

Abstract

This work aimed to simulate the water distribution of traveler gun irrigation, working with asymmetrical wetted angles and in windy conditions. In the simulations of a sprinkler with uniform radial profile, the following were considered: i) wetted angles between 180 and 330º; ii) wetted angle asymmetries from 0 to 90º; iii) wind speeds from 0 to 4.5 m s-1 ; and iv) wind direction of 0, 45, and 90º. Christiansen uniformity coefficients (CU) were calculated for strip widths from 30 to 100% of the sprinkler wetted diameter (WD). Regardless of the wetted angle adjustment, irrigations under wind speeds of 4.5 m s-1 should be avoided and strip spacings of less than 50% WD provide high CU for wind speeds up to 3.0 m s-1. For any wind conditions, asymmetries in the wetted angle led to a reduction in CU for a wetted angle of 210º. In the range of wetted angle from 270 to 330º, asymmetric adjustments of up to 20º provided a higher CU than 80% for a wind speed of 3 m s-1 and directions diagonal and perpendicular to the travel path associated with strip spacings between 60 to 70% WD, which are the spacings recommended by manufacturers of traveler irrigation machines.

Moved-Lateral, Gun, and Traveler Sprinkler Systems

“…However, the amount of water applied between time t1 and t2 (the unshaded portion of the application rate curve) enlarges the application at point 1 relative to point 2. Ge et al (2018) and Prado and Colombo (2020) analyzed the distribution of water for a pass of a traveling irrigation system using either a small or medium size gun (Figure 12.19). The depth of application was divided by the average depth applied for the ratio on the vertical axis.…”

Adaptation and Evaluation of Portable Gun Type Sprinkler Irrigation for Smallholder Farmers

“…The amount of water applied should be sufficient to reach field capacity in the root zone but should not exceed it. The water must be applied uniformly over the field so that each part of field will have the same opportunity to take in water (Prado & Colombo, 2020). For irrigated crops to reach high production, irrigation systems must have satisfactory values of water application uniformity and an acceptable Christiansen uniformity coefficient of around 80% (Darko et al, 2017).…”