Assessment of conjunctive use of surface and groundwater scenarios in Firouzabad plain

Increasing water demand is one of the most challenging issues for water resource planners and managers. Solution to water shortage problems are not solved only through development of new water resource projects, more importantly they can be solved by efficient water management within the existing projects. In this context, conjunctive use management is one of the alternatives for the optimum utilization of available water resources and can improve water use productivity. In the present study, a mathematical model is presented to evaluate different scenarios of conjunctive use of surface and groundwater with various hydrological and management constraints to arrive at optimal cropping patterns for optimal use of water resourcesfor maximizing gross margin. The results indicated that by using surface and groundwater conjunctively, reliability of the irrigation water could be improved. It caused to reduce the losses due to water uncertainty and therefore, acted as a risk management system against the uncertainty in water. Also the results showed that the net benefit from the proposed conjunctive use system is almost double from 189 to 372 milliard Rials and water productivity increaseed by 13 percent.