Modeling and Simulation of Long-term Effects of Irrigation with Tehran Treated Wastewater on Water and Soil Resources using Dynamic Systems Modeling

Many factors affect wastewater management and utilization plans’ success with any change occurring in any of these factors leading to various feedbacks on other elements of wastewater use system. Hence، development of a model with the capability of simulation of all factors، aspects and interactions that affect wastewater utilization indispensable. The objective followed in this study was to model and make simulation of long-term effects of irrigation with Tehran treated wastewater on the water and soil resources’ System Dynamics (SD) modeling method. The developed SD model validation process revealed that the model benefits from the needed acceptable efficiency. Nine possible scenarios in wastewater allocation، crop pattern as well as deficit irrigation were studied. Model results warned that the current condition if continued would lead to complete degradation of groundwater resources by 2042. Also، the results indicated that wastewater allocation can postpone the degradation of ground water resource (up to 2067). Wastewater allocation together with 11 % decrease in agricultural demand (through either deficit irrigation or modern irrigation systems’ development) can result in a sustainable use of water resources as in Varamin Area، Iran.