Agricultural, Environmental and Economic Considerations in Determining Pipe Drain Depth in Arid and Semi-Arid Regions- Case Study Azadegan Plain

There are different viewpoints in estimating basic drainage parameters¡ especially pipe drain depth. Each of these viewpoints considers different agricultural needs (aeration and salinity control)¡ environmental consideration (quality and quantity of drain water) and economic matters (drains density¡ trencher efficiency relative to the depth). Consider each one of these matters could lead drains to be shallow or deep. This paper introduces different viewpoints in determining pipe drain depth and scrutiny their results. Then¡ due to local circumstances of Azadegan plain drainage project how is under construction¡ drain depth determined by each of these viewpoints. Results shown that considering environmental matters and drain depth will be the minimum and considering salinity control will be the maximum. Results also shown that using controlled drainage in the study area for keeping groundwater table up in the irrigation season¡ avoiding over drainage¡ and keep it down in no irrigation season to avoid salt uprising could be the best solution.