Evaluatiing of Subsurface Drainage System of Abadan Date Palms with Respect to Drain Outflows and Its Effect on Water Table Depth Fluctuations Using Drainmod Model

The subsurface drainage system as a part of irrigation and drainage network of Abadan palms date field, was evaluated regarding drain outflow rate and its effect on water table fluctuations, using the Drainmod model. Through statistical analysis of values measured on the farm, and water table depth predicted by the model, standard error (S) and the average absolute deviation (α) for the years 2003-7 were obtained 6.99 and 6.33 cm, 8.94 and 8.42 cm, 8.21 and 7.82 cm, 9.2 and 8.82 cm, 9.18 and 8.93, respectively. These values indicate the suitability of project’s subsurface drainage system regarding its effect on water table depth fluctuations. Additionally, by statistical analysis of values measured on the farm and drain outflows predicted by the model, standard error (S) and average absolute deviation (α) for the years 2005-8 were achieved 1.7 and 1.43, 1.38 and 1.3, 1.13 and 1.07, 1.52 and 1.37 mm per day, respectively. These values reveal suitability of the project’s subsurface drainage system regarding its effect on drain outflows. Furthermore, considering present irrigation planning of Abadan palm date fields, water table depth fluctuations and drain outflows were predicted for 2010 using of Drainmod model. It was found out from the results gained in the present study that subsurface drainage system of Abadan date palms is appropriate not only with respect to drain outflows but also to its effect on water table depth fluctuations, because by controlling water table, it will provide palm trees with suitable conditions for growth.