تحلیلی بر سناریوهای توسعۀ کشاورزی براساس روش ترکیب خطی وزنی در محیط سامانۀ اطلاعات جغرافیایی (gis) (مطالعۀ موردی: شهرستان ارومیه)

هدف این پژوهش، طراحی یک مدل ارزیابی تناسب زمین براساس روش ارزیابی چندمعیاره-سناریو محور در محیط سامانۀ اطلاعات جغرافیایی (gis) برای توسعۀ کشاورزی در شهرستان ارومیه واقع در شمال غرب ایران است. در این رویکرد چندمرحله‌ای، ابتدا، مهم‌ترین ویژگی‌های فیزیکی زمین ازجمله توپوگرافی مطالعه شد. در مراحل بعدی، محدودیت‌های طبیعی و انسانی و درنهایت، سناریوهای محیط‌زیستی و اجتماعی-اقتصادی برای تهیۀ سناریوی توسعۀ کشاورزی پایدار ارزیابی شد. نتایج مستخرج از تهیۀ نقشۀ پایۀ محدودیت‌های توسعۀ کشاورزی براساس مدل بولین و فازی نشان‌دهندۀ آن بود که تنها حدود 12 درصد از کل مساحت شهرستان برای توسعۀ کشاورزی بدون محدودیت است؛ در حالی که حدود 64 درصد از کل مساحت شهرستان در کلاس محدودیت متوسط تا شدید قرار دارد. نتایج ارزیابی زمین در دو سناریوی محیطزیستی و اجتماعی- اقتصادی نشان از آن داشت که با توجه به شرایط حاکم بر منطقه و بحران محیط‌زیستی دریاچۀ ارومیه، سناریوی توسعۀ کشاورزی پایدار به‌عنوان یک آلترناتیو موثر توسعه در نواحی دور از دریاچه، از تمرکز فزایندۀ فعالیت‌ها در حاشیۀ دریاچه کاسته و در کاهش مشکلات دریاچۀ ارومیه و حفاظت از آن موثر است.

an analysis of agricultural development scenarios using weighted linear combination in the geographic information system environment (case study: urmia county)

the purpose of the current study is to design a land suitability evaluation model using multi-criteria evaluation (mce) and a multi-stage scenario-based analysis in the geographic information system (gis) environment for agricultural development in urmia county, north west of iran. in this multi-stage procedure, firstly, the leading physical characteristics of the region, including topography, is studied. then, to prepare a sustainable agricultural development scenario, physical and man-made restrictions, socio-economy, and finally, environmental scenarios were evaluated. the results of the base map, based on the boolean model, showed that only 12 percent of urmia county is classified as a highly suitable class for agricultural development; whereas around 64% of the total region contains moderate to highly restricted lands. the results of the land evaluation, based on the socio-economy and environmental scenarios, showed that a sustainable agricultural development scenario, as an alternative, can play an important role in decreasing activities from the surrounding area of urmia lake, and consequently act as a crucial factor for conservation of urmia lake. introductionin recent years, urmia lake has experienced severe drying and faced an ecological crisis. the concentration of the urban population and activities, such as agricultural development, has been recognized as the main factor of this crisis (valiallahi, 2020). the present study aimed to evaluate land suitability for agricultural development using multi-criteria evaluation (mce) and a multi-stage scenario-based analysis in the geographic information system (gis) environment. it is assumed that consideration of the situation of the national park of urmia lake with agricultural development scenarios not only can lead to decentralization of population in the surrounding area of urmia lake but also play an important role in spatial imbalances and activities, and consequently decrease ecological pressure on urmia lake.  materials and methodsmulti-criteria decision analysis (mcda) includes alternatives that are inconsistent and heterogeneous with quantitative and qualitative nature (malczewski, 1999; reynolds, 2014). mcda can be used both in vector and raster features (pereira duckstein, 1993). there are many mcda analyses (malczewski rinner, 2015). weighed linear combination (wlc) and boolean logic are among the most important and widely used procedures (chen, blong, et al., 2001; malczewski rinner 2005; malczewski, 2006; lafortezza, chen, et al., 2008; boroushaki malczewski 2008; jelokhani-niaraki malczewski, 2015). research findingsafter preparing base and constraints maps, agricultural development is evaluated under different scenarios (pourebrahim et al., 2011, p. 90). in socio-economic, results extracted from the final map indicate that lands with no or marginal limitations are mostly located in the eastern part of urmia county, where the region slope is low and soil is highly suitable for agriculture. in the environmental scenario, out of 61 percent of the suitable area (booleans region 1), 12 percent is classified as highly suitable, 25 percent as suitable, 27 percent as marginal suitable, and 36 percent as low and very low suitable classes. out of the total area of urmia county (5274 square kilometers), 7 percent is classified as highly suitable, 14 percent as suitable, 15.5 percent as marginal suitable, and 63.5 percent as low and very low suitable classes. so, the results show that severe limitation is the main constraint for agricultural development nearly in one-third of the total area. in the sustainable development scenario, the results extracted from the final map showed that 14.61 percent of the boolean region is located in highly suitable areas, 24.6 percent in suitable areas, 24.94 in marginally suitable areas, and nearly 36 percent in low and very low suitable areas. the results also showed that out of the total area of urmia county, 8 percent is classified as highly suitable, 14 percent as suitable, 14 percent as marginal suitable, and 64 percent in low and very low classes.  discussion of results and conclusionsbased on the results, the majority of suitable lands are located in the western parts of urmia county, hovasin, gangachin, and ziveh deserts. based on the environmental and geographical characteristics of the region and also the results of the current study, the characteristics of the region’s land are determinants and prerequisites for any development plan in urmia county. in regions similar to urmia, which enjoy high environmental and man-made potentials, land suitability using mce-gis and a multi-stage-scenario-based procedure can lead to spatial balances, decrease environmental and ecological pressure, and also change the current crisis into land use and spatial planning by planners.