Title: Assessing Potentials of Rainfed Lands and Optimum Water Allocation between Irrigated and Rainfed Lands (Case Study: Qazvin Plain)
Abstract: In this study, water allocation managements between irrigation and rainfed lands were surveyed in different climate conditions. Objective function was maximizing the net benefit. It is supposed that the cropped area of irrigation and rainfed lands have been kept unchanged and deficit irrigation has been only applied to a part of irrigation lands while supplementary irrigation has been applied to a part of rainfed lands. Also the total available water in each decade in initial management is allocated in the same decade or until 4 decades later to the irrigation of same crops in deficit irrigation conditions and in supplementary irrigation conditions for rainfed crops. The optimization model results in the Qazvin Plain indicated net benefit increased under new water allocation management in case of water conveyance from 2000, 4000, 6000, 8000 and 10000 meters in a climatically normal year to be 11.1, 13.5, 19.2, 16.6 and 15.8 percent, respectively, while in a wet year 9.0, 10.9, 17.0, 15.9 and 13.4 and in a dry year 8.05, 12.5, 16.1, 19.1 and 19.9, respectively. Also barley was the best choice for deficit irrigation in three climate conditions. Depths of deficit irrigation were 20, 25 and 30 mm in the first decade of November and 50, 50 and 60 mm in the second decade of May in normal, wet and dry conditions. Also lentil was the first choice for supplementary irrigation. The best treatments for supplementary irrigation in lentil rainfed fields were 75 mm in the third decade of May in normal years, 75 mm in the second decade of May in wet years and 100 in the second decade of May in dry years. With these treatments, the yield of lentil increased from 1000, 1300 and 0 to 3000, 3000 and 2000 kg/ha in normal, wet and dry years, respectively.
Publication Year: 2014
Publication Date: 2014-01-01
Language: en
Type: article
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