Introduction

The agricultural sector has an essential role in the economic and political life of societies. Considering the limited available resources and the increasing demand, it is necessary to carry out accurate and comprehensive planning in the geographical fields in order to develop activities and use resources. The geographic information system is also one of the methods based on location analysis, with the help of which it is possible to know the environmental capabilities and capabilities of each region in order to zone the areas prone to agricultural activities and take steps towards the development of this sector. becomes Cultivation of rapeseed, as one of the products with high diversity, has special environmental conditions. According to its geographical location, Izeh county seems to have a suitable capacity to cultivate this product. The current research has tried to determine the zoning of areas prone to rapeseed cultivation based on environmental criteria, with spatial decision making method (AHP) and weighting model (IO) in GIS environment.

Methodology

The present research is descriptive-analytical and in-depth in terms of its applied and developmental purpose and in terms of its nature and method. In order to zone the Izeh region in terms of areas prone to rapeseed cultivation, the desired layers were digitized using AHP method. Then, based on the existing conditions in terms of the investigated factors, the criteria were prioritized and according to the AHP model, the criteria and options were evaluated, based on which the data was overlapped and analyzed in the Weighted Sum Overlay option. , was discussed in ARC GIS environment and Expert Choice software. The layers used in this analysis are the geological layer, soil, erosion, elevation model, slope, vegetation and type of use. Also, in the weighting model (IO), different weights are given to different complications and different existing classes, and flexible combinations are obtained from the maps, which include a range of numbers. In this way, after applying different weights on the inner classes of each layer, then all the layers are overlapped. This overlap can be done through different functions in the GIS environment.
 

Results

The results show that according to the AHP model, of the total area of 29018.55 hectares, i.e. 7.7%, it has a very suitable condition in terms of the seven criteria under investigation. As an example, this area has a low slope, suitable height, erosion below 5%, land use with suitable cultivation, deep soil with suitable texture, etc. In the IO method, the first zone covers 23604.40 hectares (6.3 percent) of the region. The difference of this area in two maps is one percent. The second zone in the first method, with an area of 404,061.19 hectares, is ranked second in priority. The conditions mentioned in the first zone are also present in this zone, which of course becomes a little weaker. However, it is favorable for the cultivation of rapeseed. This zone is adjacent to the second zone. In the IO method, this area is 37456.36 hectares and these two areas are almost the same.
 The other three zones, which have moderate, unfavorable and very unfavorable conditions, cover 85152.42 hectares, 147601.00 hectares, and 71223.75 hectares of the area, respectively, in the AHP method. The environmental conditions investigated in these three areas are weaker than the first and second areas, respectively. These areas have soil with shallow depth and inappropriate and stony texture, inappropriate use, tree and mountain vegetation cover, high altitude and lack of access, high and inappropriate slope, lithological structure and poor structure for rapeseed cultivation.
 In the weighting method (IO), more than 37456.36 hectares of the region have a suitable condition based on this method. 110754.3 hectares of the area of Izeh county have average conditions for rapeseed cultivation, which this method is approximately 7% of the area. It includes more than the first method. Also, more than 145,308.17 hectares of the area are in poor condition and 26,405.56 hectares have very unsuitable conditions for rapeseed cultivation. Comparing the IO method with the AHP method shows that in both methods, the suitable area has certain conditions and in the unsuitable area, the IO method includes 4% more area. These areas usually have limited soil, medium to high slope, medium height, etc.
 

Discussion

According to the AHP method, 18.5% of the area has a suitable condition for rapeseed cultivation, such that it has a high potential in terms of the seven research criteria. This situation in the IO method is 16.3%. Also, 58.5% have unfavorable conditions and limited criteria for rapeseed cultivation in the study area based on the AHP method. This amount in the weighting method is 54%. In general, the two methods have many points in common in the assessment of rapeseed cultivation in the study area. Both methods have almost the same results in terms of area and geographic location of the zones. It is important to mention that in terms of the comparison of the zones, almost five zones in the two maps have overlapping status and are marked with a slight decrease and increase in area in common places. Based on the evaluation of rapeseed cultivation, it seems that both methods (AHP) and algorithm (IO) have the same results and both methods can be used. The results of this research on the efficiency and effectiveness of the used models including AHP and OI and their combination with GIS, with the results of Tadsi et al.(2020), Mandal et al.(2020), Singh et al.(2020), Moradi et al. (2019) and Sobhani and Nasiri (2021) are consistent.
 

Conclusion

The conclusion of the research shows that the region has a favorable capacity for rapeseed cultivation. This capacity was well-confirmed based on environmental criteria. In addition, the two models used in the research have the necessary efficiency to evaluate and measure the environmental potential for cultivation and agriculture.