Drainage Water Management of Irrigation and Drainage Networks of South West Khuzestan

Soil salinity and shallow and saline groundwater have been made subsurface drainage and drainage effluents to be inevitable in irrigated lands of south of Khuzestan. Due to the development of irrigation and drainage networks (IDN) in the southwest of Khuzestan (with an area of 340,000 hectares), it is necessary to study integrated agricultural drainage management in all area. Drainage management is depending on its quality and quantity (Q & Q), which are changing continuously. Therefore, a model for predicting drainage water Q & Q in the operation period of IDNs was developed and validated using 25 hectares' research field. Predicted drainage water salinity of the IDNs was used to make the decision for reusing or disposing options. Based on the predictions made by this model, the quality of drainage water from the plans of the southern Karkheh basin and western Karoon, with the exception of sugarcane cultivations, is not suitable for at least 10 years to cultivate salt-tolerant plants and their disposal is inevitable. In case of drainage water with better quality, it could be reused for irrigation of salt-tolerant crops and forestation to prevent dust storms. Drainage transportation to the Persian Gulf is proposed to have the least hazard to the environment. In the present study, the content of phosphorus and nitrogen in drainage water was measured to be 0.043-0.70 and 2.2-22 mg/L respectively, which showed a much higher amount of nitrogen than Mahshahr bay (discharge point). Although drainage disposal into the Persian Gulf seems to release high levels of nitrogen, however, due to low phosphorus content in these drainage waters, additional nitrogen cannot be entered in the production cycle and does not result utrification.