Optimization of the irrigation water resources for Shijin irrigation district in north China

• The paper aims to optimize irrigation water resources for Shijin irrigation district in north China.
• A nonlinear fuzzy interval irrigation optimization model is developed.
• The method can deal with interval values and fuzzy numbers in objective function.
• The solutions can provide effective agricultural water allocation plans by improving economic benefit under preset scenarios.

In this study, a nonlinear fuzzy interval irrigation optimization model is developed for optimal agricultural water allocation in Shijin irrigation district, Hebei province, China. The developed method can deal with interval values and fuzzy numbers in a nonlinear objective and a set of constraints including water availability, evapotranspiration, reservoir water priority, fairness, etc. Three different scenarios (under dry, normal, and wet years) were considered. As the result, the optimal water allocation schemes, both from reservoir water and ground water, were obtained. Under fuzzy degree of membership level that equals to 1.0, the system benefits are 1.53 × 109 RMB for dry years, 1.61 × 109 RMB for normal years and 1.61 × 109 RMB for wet years. The solutions can not only provide an effective evaluation under preset scenarios, but also reveal the associated economic implications. Three aspects have been improved in this study compared with previous studies: (1) the model has capability of incorporating multiple water resources, multiple subareas, multiple crops, and multiple growth stages of water resources management within the optimization framework; (2) in order to address the uncertain parameters which are not sufficient or imprecise in the practical problems, a nonlinear fuzzy interval irrigation optimization model (NFIIOM) is developed by incorporating interval parameters programming and fuzzy programming; (3) after applying the developed model to a real case study, the reasonable solutions has been gotten and the results can be used to help the manager to establish effective water allocation plan for agricultural irrigation systems under uncertainty, and thus maximize the benefit of local farmers.