Effect of water pricing on persuading farmers to use modern irrigation systems and increasing the economic productivity of irrigation water (Case study: Qazvin Plain Irrigation Network)

Increasing water productivity is one of the mechanisms for water use management, and economic methods such as water pricing, are one of the solutions that reduce water consumption and increase water productivity. In this research, the impact of water pricing on increasing the water productivity in the irrigation network of Qazvin plain by the aid of modern irrigation systems was investigated. Therefore, regarding existing information comprised of network construction costs, ongoing costs and other expenditures, the cost for per cubic meter of water in the irrigation network of Qazvin plain was estimated based on the engineering economics method in 2018. Then, according to the cropping pattern of the network, the net irrigation requirement of each crop and its associated costs and incomes, the economic productivity of each crop was investigated regarding to four different scenarios The results illustrated that the price of water sales in the irrigation network is much lower than its real price. Water pricing in irrigation network due to a rise in farming costs has led to encouraging farmers to implement modern irrigation systems as well, and consequently resulted in a reduction in water consumption and increased water productivity in the irrigation network of Qazvin plain. Thus, if farmers implemented modern irrigation systems in their fields, economic water productivity in the network would increase and the government could sell the water to the farmers at a realistic price.