GIS-Based Land Capability and Suitability Evaluation for Irrigated Agriculture (Case Study: Karaj-Qazvin)

 Farmers and agricultural products face many risks, including adverse weather conditions, pests, diseases, and changes in product prices, laws, and regulations. The first step in managing and minimizing many of these risks is often choosing the right crops for the area under cultivation; Therefore, knowing whether these lands are suitable for a particular crop can determine the success or failure of agricultural strategies. Because farmers are exposed to climate change and the economy, where agricultural frameworks are changing at an unprecedented rate, it is vital for them to be able to adapt to new trends. Increasing the availability of land suitability information for agricultural products will be a valuable aid for farmers and managers in this field to develop new agricultural strategies. At the same time, the growth of computational capabilities and increased access to geographic data has made land suitability assessment faster and easier.

 The study area is located in Abik city, a city located in Qazvin province of Iran, between 50 degrees and 40 minutes to 50 degrees and 41 minutes east longitude and 35 degrees and 52 minutes to 36 degrees and 21 minutes north latitude. The average annual soil temperature at depth of less than 50 cm is 15.8 °C and has thermal heating regime. Furthermore, according to the average rainfall of the region, 222.7 mm, the humidity regime of the region is of Eridic type. Moisture and heat regimes were obtained by Newhall software. According to regional conditions and the size of the area, 60 profiles were drilled for network description and sampling. Field studies including determination, drilling, description of profiles, slope percentage, etc. were determined at the site. Information on soil physical and chemical properties were tested. Parametric, American (USDA) and LSP methods were used to evaluate the land. Necessary climatic characteristics for annual plants include the climatic variables that are necessary to determine the growing season, planting date and type of cultivar. The information of Buin Zahra synoptic station has been used. In this study, CROPWAT software was used to calculate the potential evapotranspiration. Land information such as slope, drainage Condition and flood absorption, as mentioned in the profile description card, was used to assess land suitability. Growth period was also obtained for the region using the area agronomical calendar. To calculate potential of production, the model AEZ which is provided by FAO, is used in this research.

 The decrease in the suitability of the studied lands for the wheat crop is due to the salinity and sodium content of the lands and the presence of surface gravel and shallow soil depth. According to the provided tables and maps, 18% of the study area is unacceptable, 12.5% is average, 12.5% is good, 25% is very good, or very good and 31.25% of the total study area are in the excellent fitness class. The above values have been obtained by considering the rangeland and saline sections as well as the type of product in preparing the fit map. The accuracy of the preferred rational scoring method in land suitability is higher than the parametric method because in this method the land suitability maps of the area are obtained by logical collectors and the output map is the result of all parameters and constraints that the area may have. To have the desired. In the parametric method, this problem is summarized in soil properties and climatic conditions. Due to the lack of direct measurement of product performance, more accurate comparisons were not possible.

 Most of the restrictions were in shallow hilly areas with shallow soils and pebbles, and salinity, alkalinity and gypsum did not impose any restrictions in these areas. Traffic in these areas was difficult and they were mostly in the S3 class by the parametric method and the poor and unacceptable class in the LSP. In land evaluation using LSP method, understanding the relationships of criteria with each other and the amount of impact that each has on the potential of land for different uses is essential. The LSP method is sensitive yet flexible, and may not work well if the data accuracy and number of parameters are low. The application of GIS-based LSP method showed a suitable tool to create accurate, flexible and rationally justifiable criteria in assessing the capability and suitability of land in agriculture. In such studies, by using the Bayer LSP method, prerequisites such as precisely defining the goals of users, managers and agricultural expertise should be considered. This method is a multi-criteria evaluation method that has been improved for measurement among decision makers, land management and other specialties.