عنوان مقاله [English]
Study of seepage in irrigation canals has been widely considered by researchers due to the importance of water losses, degradation of the land and environmental problems. Canal lining cracks is one of the main reasons of the water losses and reduction of water delivery efficiency. In this study, seepage rate in three concrete lined canals of Marvdasht Plain (Fars Province), were evaluated using SEEP/W, MSEEP and empirical models, and compared with ponding method results. Results of SEEP/W and MSEEP models showed no significant difference to the results obtained from ponding method. Results of SEEP/W model showed 11.3 percent of error comparing with ponding method in the first canal. For the second and the third canals this error was about 16.8 and 12.6 percent for MSEEP model, respectively. Using ponding method, the final seepage rates were about 402.8, 434.9, 218.8 mm per day in the three canals, respectively. The final seepage rate obtained by SEEP/W model was 448.3, 513.7, and 269.0 mm per day in three canals, respectively. The final seepage rate estimated by MSEEP model was 530.4, 508.2, and 246.3 mm per day in the three studied canals. The empirical seepage models were calibrated using the data obtained from ponding method in the studied region. The differences between results of un-calibrated Misra model and ponding method were not significant for the first and the third studied canal. The errors of seepage estimation for these canals were 9 and 37.1 percent, respectively. The difference between ponding method and other empirical models were significant. Among the modified empirical models, the results of Davis and Wilson, and Ingham models were closer to ponding method. The coefficient of determination and estimation error of Davis and Wilson model was 0.8486 and 2.23 percent error, while for Ingham model these values were 0.8430 and 2.27 percent, respectively.