الفهرس 
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Abstract
Objectives: 1. Develop a computer model, simulating sprinklers water overlapping pattern using a single sprinkler water distribution pattern under operation conditions indicating the corresponding uniformity coefficient. 2. Test the computer model against different sprinklers shape arrangements and prove its validity in various irrigation conditions. 3. Make use of the model to calculate sprinklers overlapping pattern application efficiency, storage efficiency and deep percolation, for plant needed water application depth. Methods and results: Method HEDIA computer model instated in this study used the single sprinkler superimposition in the model to simulate sprinklers overlapping pattern shape and space. In order to validate and verify the accuracy of HEDIA computer model two steps were done. -The first step of validation HEDIA computer model was conducted in Research Laboratory of National Irrigation Laboratory of Agriculture Engineering Research Institute (AEnRI), Dokki, Giza, Egypt. where the outputs of the model have been compared with actual data collected from the lab test. - The second step of verification HEDIA computer model accomplished by comparing the output of HEDIA model by the results from CATCH3D computer model, version 4.60 and the actual laboratory data got from step one. The measured data consist of one sprinkler water distribution pattern and three several sprinklers overlapping pattern shapes ”square, rectangle and triangle” under same operation condition. Results :• HEDIA grid simulation for square overlapping pattern got coefficient of determination of 0.96 and slope 0.98 comparing with actual data. • In square overlapping pattern HEDIA radial simulation get R2 = 0.92 when b = 0.98 that with actual data. • HEDIA grid simulation for rectangular overlapping pattern data justifying the actual data with R2 = 0.97 and b = 1. • HEDIA radial simulation for rectangular overlapping pattern data simulates actual data with coefficient of determination of 0.95 and slope of 0.99. • Simulation of HEDIA model in triangle overlapping pattern gets coefficients of determination of 0.97 for the two simulations and slope of 1 and 0.99 respectively for grid and radial simulation with the actual data. • Analysis of variance between linear and normal distribution fit performance parameters in actual and simulated grid and radial data not significant. • For sprinklers overlapping patterns mean water application depths and christiansen uniformity coefficient, HEDIA and CATCH3D output results more correlated to each other when neglecting CATCH3D insufficient results in even triangle overlapping patterns so: • In quarter part sector grid data simulation, HEDIA and CATCH3D model coefficients of determination for means and uniformity gets 0.99 and 0.97 with slope 1 and 0.99 respectively. • In one radial data simulation, coefficient of determination between HEDIA and CATCH3D model means water application depths get 0.99 with linear slop 0.98. The same reaction act between the two models uniformity coefficient which gets R2 = 0.99 and b = 0.99. • HEDIA model more accurate than CATCH3D in simulating several numbers of radials data and in simulating even triangle sprinklers overlapping pattern shape. • HEDIA model can calibrate any established sprinklers overlapping patterns by adjust the data of overlapping pattern. • HEDIA model calculate operation time under the selected water application depth and can increases the percent of areas that in deficit analytically and calculate the needed water volume to be applied and the volume of water lost. • HEDIA model can calibrate the new sprinklers in laboratory test by just one quarter part sector of grid water data or by one radial of water data so simplify the hard work don and consuming the time of calibration. • HEDIA model packaged to be operated on any computer system.