A GIS model for the assessment of water resources suitability for livestock grazing

The study presents a model for quantitative, qualitative and spatial distance assessment of water sources suitability for livestock grazing based on geographic information systems (GIS). The research was carried out on rangelands of Piranshahr in West Azerbaijan Province, Iran, in 2011. The framework of the study was based on FAO method for land evaluation (1991) in which water suitability classification is one of the sub models. To reach this goal three factors, quantity, quality and water resources distance, were assessed. Successively, in order to obtain final water suitability for livestock in the area, these three factors were considered together. The final water suitability map was produced and areas were classified in four orders: high suitable (S1), moderately suitable (S2), marginally suitable (S3), and not suitable (N). The results of the study revealed that in the area, in all the Samman units (areas with water resources reserved for livestock drinking, made only available to several allowed utilizers) used by cows and sheep for grazing there were no limitations in terms of quantity and quality of water resources and all of them could be placed in S1 suitability class. Considering the three sub models together, the following results for sheep were obtained regarding final suitability: 77.30% of study area located in S1 suitability class, 21.77% located in S2 suitability class, 0.93% located in N suitability class. Results of final suitability for cows showed that 41.49%, 38.91%, 3.28% and 16.32% of study area are located, respectively, in S1, S2, S3 and N suitability classes. Slope is the only limiting factor. Availability of water sources is important to manage properly livestock grazing, minimizing uneven use of rangelands. The use of GIS spatial models can be suitable to localize the proper areas for livestock production, with the aim to improve productivity.