DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS Valín Sanjiao M.I.; Santos Pereira L. Agricultural Engineering Research Center, Institute of Agronomy, Technical University of Lisbon. WATER SAVING IN MEDITERRANEAN AGRICULTURE & FUTURE RESEARCH NEEDS CIHEAM, Mediterranean Agronomic Institute of Bari, Italy
THE MODEL Conceptual structure Start DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS Design new systems Evaluation of operating systems Gross irrigation requirements Input data field Hydraulic simulation Spans Emitters Systems Computation of emitters chart Computation of performance indicators Occurrence of runoff N Acceptable runoff? End Y
THE MODEL Gross irrigation requirements DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL Hydraulic simulation DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL Selection the emitter chart DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS
THE MODEL Calculation of the application rate DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS Compare Run off
THE MODEL Performance indicators DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS
MODEL APPLICATION Performance indicators in field evaluations The results analyzed herein refer to field evaluations of center-pivot systems in operation in Alentejo (Portugal) DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS
MODEL APPLICATION Performance indicators in field evaluations Main problems were: high working pressure, ranging from 476 kPa to 555 kPa, much above recommended pressure for systems with FSPS emitters; high wind drift and evaporation losses due to small diameter of droplets as a result of high functioning pressure of emitters; and application rates excessive relative to soil infiltration rates. These problems result of poor design, mainly relative to the selection of spray heads which were not in agreement with the existing characteristics of the pressurized distribution network and the characteristics of the soils and relief in the area. DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS
MODEL APPLICATION Performance indicators obtained in DEPIVOT The model DEPIVOT was used to simulate alternatives to the existing systems DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS
CONCLUSIONS The operation pressure is excessive DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS The operation pressure is excessive Runoff was also often produced due to high application rates Small drops that easily evaporate or are drawn by the wind Field evaluations of center-pivot systems have shown that these systems are often poorly designed and the selection of emitters is often inappropriate Friction losses observed were often greater than 20% of the operation pressure
DEPIVOT shows that it is possible to: CONCLUSIONS The model DEPIVOT was conceived to support farmers in selecting new systems and improving the existing ones. DEPIVOT shows that it is possible to: achieve much better performances; reduce the operating pressure and save energy; control wind drift and evaporation losses, control runoff DEPIVOT, A SOFTWARE TOOL FOR IMPROVED WATER USE WITH CENTER-PIVOT SPRINKLER SYSTEMS The beneficial water use.