A SOFTWARE TOOL (CPSIP) FOR APPROPRIATE DESIGN AND EVALUATION OF CENTER PIVOT SPRINKLER IRRIGATION SYSTEM

Abstract

The experimental work was conducted in the River Nile Sate, Sudan, with a view to developing a simulation model (CPSIP) for designing and evaluating a center pivot sprinkler irrigation system. A Visual Basic 6.0 program was used for the model application windows. The program is interactive for designing a new system and/or for evaluating an already designed system. It is composed of simple windows interfaces. The special real objects (input data, design criteria, chemigation, system evaluation and model outputs) are implemented as User Controls in relation to their need for an interface capable of triggering events. The model computations are supported by a database on the system components and characteristics. The crop water requirements estimates and pipe sizes selection can permit attaining a target performance. In the evaluation mode, the center pivot hydraulic characteristics, its hardware specifications and the performance indicators are executed. The model accuracy has been validated by comparing its output with the actual system design criteria. Two center pivot systems were tested at Ras Elwadi farm and the Jordanian Bashair project during the periods (2007/2008). The results covered irrigated area, unirrigated area, readily available water, reference evapotranspiration (ETo), crop water XV requirements, irrigation interval and application depth. For Ras Elwadi farm they were found to be 43.7 ha, 11.9 ha, 49 mm, 8.11 mm/day, 8.9 mm/day, 6 days and 70 mm, respectively. While for the Jordanian Bashair project they were 55.4 ha, 15.1 ha, 49 mm, 8.11 mm/day, 9.3 mm/day, 6 days and 70 mm, respectively With respect to the hydraulic characteristics and hardware specifications it was found that the center pivot system discharges were 318.8 m3/hr (1400 gpm) and 227.2 m3/hr (1000 gpm) for Ras Elwadi farm and Jordanian Bashair project, respectively. On the other hand the packages of Low-Drift Nozzles (LDN) were 116 nozzles with 2.8 m spacing and 214 nozzles with 1.9 m spacing for Ras Elwadi farm and Jordanian Bashair project, respectively. The ratio of actual (measured) to calculated nozzle discharges and pressures were respectively within the ranges of 0.82 to 1.13 and 0.97 to 1.17 for Ras Elwadi farm and 0.84 to 1.90 and 1.03 to 1.23 for the Jordanian Bashair project. The coefficient of uniformity (CU) and distribution uniformity (DU) for Ras Elwadi farm were 82.7 % and 48.3 %, respectively whereas they were 77.2 % and 67.4 % for the Jordanian Bashair project, respectively.