Accuracy assessment of volume balance model solution methods in estimation of advance phase of furrow irrigation

Subject Areas : Farm water management with the aim of improving irrigation management indicators

Sonia Zebardast ¹ , Hamed Riahi Farsani ² , Sayyed Hasan Tabatabaei ³

1 - Ph.D Student, Department of Water Engineering, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran
2 - Ph.D Student, Department of Water Engineering, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran
3 - Associate Professor, Department of Water Engineering, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran

Received: 2013-11-09 Accepted : 2015-02-02 Published : 2014-12-21

Keywords: advance phase, furrow irrigation, subsurface shape factor coeffi, volume balance model,

Abstract :

Nowadays optimal management and conservation of water and soil resources seems to be more essential than ever before. The issue of surface irrigation systems as a major consumer of water in the country is very important. Accurate prediction of the advance phase is important for the design and evaluation of these systems. The main objective of this study was to evaluate the accuracy of solving methods of Volume Balance Model (VBM) in the estimation of the water advance of furrow irrigation. In this study, Michel, Philip, Power functions and Return functions solving methods were used and also new models were proposed. For each method, a computer program was written in Matlab and to measure the precision of solving Methods mentioned above, gathered data of seven fields in two-time irrigation (A: water-soil and B:middle growth) in Chaharmahal and Bakhtyari province were used. The statistics of solving methods mentioned were obtained by use of root mean square error (RMSE), coefficient residual mass (CRM) and model efficiency factor (EF). The results showed that Michel method has a lower RMSE (27.6 and 57.6 meters values for two-time irrigation respectively) and CRM (0.06 value) and the higher EF (-1.07 value) than the other solving methods of volume balance model. Other methods have close results for RMSE (33.3 and 61.4 meters values for two-time irrigation), CRM (0.21 value) and EF (-2.65 value). As a result, the best method to solve VBM is Michel's method. Accurate determination of infiltration coefficients and selection of infiltration equation are effective factors for model accuracy. Therefore, considering subsurface shape factor effect, the best suggestion for this coefficient is Kiefer equation.