Using Geographical Information System and Remote Sensing to Assess Suitability of Wheat Fields Affected by Climatic and Topographic Factors: A Case Study in Golestan Province, Iran

摘要

In this study remote sensing (RS) and Geographical Information System (GIS) were integrated to detect cultivated wheat fields and to identify the suitability of those fields with respect to topographic and climatic factors affecting wheat yield. For this purpose, all raster layers related to climatic and topographic factors were provided by using different spatial functions and cultivated wheat fields were detected by a supervised detection method. Five different scenarios were considered to assess the consistency of wheat fields with suitable conditions. Among the five scenarios, fields with a slope < 12%, and > 24°C (irrespective of rainfall value and aspect) covered 90.5% of all detected fields. 74.2% of current wheat fields were located in theNorth, and the study area did not have suitable conditions with respect to average temperature, but had a suitable slope and minimum and maximum temperatures. The temperature of the study area was in the range of cardinal temperatures for all common wheat cultivars cultivated in Golestan province. The area was not affected by salinity or pH restrictions and although 87.4% of fields had yield exceeding long-term recorded data, the absolute yield in the wheat fields was not high. Our results indicate thatwheat grain yield in the study area changed from 1.6 to 4.4 ton ha~(-1). Long-term average yield of wheat in this area is 3.5 ton ha~(-1). Results revealed that integrating RS and GIS can help to identify field restrictions and to assess the problems and probable opportunities to improve obtainable yield and estimate the yield of wheat fields.