اثر بازگشت به‌حالت اولیه یا معمای جیونز: مفهومی برای درک مناسب‌تر پیامدهای بهبود کارایی آب

Water scarcity is a major and structural problem in arid and semi-arid regions across the world that greatly concerns environmental policy-makers. The problem of adjusting the demand exceeding the sustainable supply has been mainly tackled with demand policies, particularly through investment in water saving technology and promotion of irrigation efficiency programs. However, there have been very few evaluations of these programs and many of those that exist raise serious doubt about the programs’ effectiveness in reducing the consumptive use of water, due to the occurrence of the rebound effect. In this study, a sample of 243 farmers in Fars province who have the sprinkler irrigation system installed in their farms was interviewed to collect needed data for investigating the rebound effect using AHP and ordered logit regression model. The results indicated that 74.5 percent of sampled farmers have experienced medium to large rebound effect. It was also found that the amount of dry and fallow land during installation of sprinkler irrigation system have a positive relationship with the probability of occurrence of the rebound effect. Finally, the results of this study can be used to determine the probability of the rebound effect occurrence after installment of the sprinkler system for farms where data is available. For example, in the farms with farm features 24, probability of the rebound effect as a result of water saving measures at the low, medium and high levels are 0.4, 32 and 67.4 percent, respectively. Therefore, we must apply specific water conservation and efficiency practices in such farms based on a combined use of technical, economic, social and political tools to reduce pressure on scarce water supplies.