Multi-Criteria Evaluation of Small-Scale Sprinkler Irrigation Systems Using Grey Relational Analysis

The technical and socioeconomic evaluation of small-scale sprinkler irrigation systems is a multi-criteria problem characterized by complexity and uncertainty. In order to solve that, the application of Grey Relational Analysis (GRA) was presented. An evaluation model with ten sub-criteria under four groups, namely, technical, economic, environmental and social, was established. Among the criteria, calculation method of labor use in the small-scale sprinkler systems was originally addressed, and Life Cycle Cost (LCC) was used as an economic indicator. In the design of GRA, a combination weighting method based on Analytical Hierarchy Process (AHP) and entropy measurement was employed to take into account the experts' knowledge and the inherent information in the experimental data. Six irrigation systems for three field sizes 0.5 ha, 2 ha and 5 ha respectively were considered to verify the model. The systems were optimized with Genetic Algorithms (GAs) first to figure out the optimal combinations of sprinklers and pipes and further, field tests were performed. The discussions show that: the developed approach has successfully provided the ranking of systems for three field sizes. When different types of sprinklers are used, the criteria including atomize index, application efficiency and specific energy consumption change greatly. And the ownership cost, particularly the energy consumption fee, accounts for the largest part of LCC in most of the systems. In comparison, System 5 and System 1 are generally the best. The evaluation model solved by GRA integrated with GAs is effective and can be extended to the comprehensive evaluation and optimization of other irrigation systems.