University of TehranIranian Journal of Soil and Water Research2008-479X51220200420Scaling of Volume Balance Equation in Border IrrigationScaling of Volume Balance Equation in Border Irrigation3533627358710.22059/ijswr.2019.285370.668261FAMohammad MahdiChariAssistance Professor ,Water Engineering Department, Faculty of water and soil, University of Zabol, zabol, Iran,0000-0002-1847-973XJournal Article20190720In most cases, advance data is used for evaluating border irrigation. Due to soil variability, as well as initial and boundary conditions in border irrigation, water advance rate varies considerably in different borders. Scaling techniques helped to reduce the required measurements in soil and water issues. The aim of this study was to scale the volume balance equation and provide a simple equation to determine water advance in border irrigation. For this purpose, 21 borders, including cultivated and uncultivated borders with slope of 0.001 to 0.005, roughness of 0.017 to 0.211, length of 91.4 to 100 m, and discharge rate of 0.08 to 0.16 m<sup>3</sup>/m/min were used. Scale factors were defined such that the volume balance equation remained independent from soil and initial conditions. The scaled advance curves showed certain patterns. As a result, empirical equations were fitted to the scaled solutions. The empirical equation was evaluated for prediction of water advance in the border. The root mean square error obtained from the observed and calculated values by the experimental equation for the different borders, in most cases, was less than 5 minutes, and the mean absolute error value was less than 10%. The determination coefficient of the final advance from observed and calculated values by the experimental equation was 0.93. In general, simple form and independent to the soil type equations presented are advantages of this method.In most cases, advance data is used for evaluating border irrigation. Due to soil variability, as well as initial and boundary conditions in border irrigation, water advance rate varies considerably in different borders. Scaling techniques helped to reduce the required measurements in soil and water issues. The aim of this study was to scale the volume balance equation and provide a simple equation to determine water advance in border irrigation. For this purpose, 21 borders, including cultivated and uncultivated borders with slope of 0.001 to 0.005, roughness of 0.017 to 0.211, length of 91.4 to 100 m, and discharge rate of 0.08 to 0.16 m<sup>3</sup>/m/min were used. Scale factors were defined such that the volume balance equation remained independent from soil and initial conditions. The scaled advance curves showed certain patterns. As a result, empirical equations were fitted to the scaled solutions. The empirical equation was evaluated for prediction of water advance in the border. The root mean square error obtained from the observed and calculated values by the experimental equation for the different borders, in most cases, was less than 5 minutes, and the mean absolute error value was less than 10%. The determination coefficient of the final advance from observed and calculated values by the experimental equation was 0.93. In general, simple form and independent to the soil type equations presented are advantages of this method.https://ijswr.ut.ac.ir/article_73587_0716a0d86b708bb3090402cd5ee65b53.pdf