Identification of optimal and suitable sites for pistachio orchard replacement using spatial overlaying methods in GIS: A case study in West Azerbaijan, Iran

Replacing regular high-water-consuming crops with tree species tolerant to salinity and drought, such as pistachio, has been suggested to reduce social and economic crises around Urmia Lake in the West Azerbaijan province of Iran, which has been negatively impacted by climate change and water resource mismanagement. In the current study, to determine suitable sites for pistachio production, the climatic requirements of the pistachio tree were determined, and relevant data, including a map of land use, soil type and limiting factors (salinity), average temperature, relative humidity, elevation, slope maps, and layers were collected from local meteorological and agriculture administrations. All data were prepared as grid surfaces and raster layers in GIS to produce digital layers of individual factors. A spatial overlaying analysis was used to assign weights to each variable in each layer cell, and finally, suitable sites were determined with overlay analysis. According to the results, there are potentially about 195 thousand hectares of relatively suitable areas in different regions of the province. However, considering the restricted water sources at the study site, it is recommended that the extension of pistachio orchards be targeted and timed based on maximizing profit and minimizing the use of water resources. Moreover, it should mainly focus on replacing worn-out and non-economical units and high water-demanding crops (approximately 30,000 hectares). To validate the results, all previously cultivated areas were collected and compared with targeted suitable regions, indicating that about 90.42% of pistachio orchards in the province are in suitable areas for pistachio cultivation. Buffer zone areas of Urmia Lake are among the most suitable areas. Eventually, the area under the Receiver Operating Characteristic curve related to observed fields was 0.92, which demonstrates high performance in targeting suitable areas.