Zonation of topoclimatic potentials of rain-fed wheat cultivation in Kermanshah Province

The dominant agricultural land uses are included of wheat farming in the Kermanshah providence in the northwest of Iran. The objective of this paper is Analyzing of topoclimatic zonning of the wheat dry farming areas based on overlying the climatic and topographic character tics. To achieve the exact date of stages of rain-fed wheat growing in different areas of the province, the degree-days temperature method was used. The next step the researchers took was the measurement of annual, autumn and spring rainfall amounts for all the stations throughout the province. Then the probabilities of suitable temperature for germination were computed; as well as, a maximum temperature of 25 to 30 ° C or higher was determined to be appropriate at flowering and grain-filling stages. The calculated values were converted to different zones by weighted average method (IDW) in GIS. Also using Digital Elevation Model (DEM) of the province, elevation and slope classes were calculated for the whole province. Finally, by pooling and studying the data layers using “weighted classification” method, the final map of the suitable areas for the rain-fed wheat cultivation in Kermashah province was prepared. The results show that moving from east to west of the province, the terrain becomes more favorable for rain-fed wheat cultivation and the process is parallel to the distribution of annual rainfall in the province. Among the parameters studied in this research, the annual rainfall is the most important. Moreover, through the superposition of the effective layers in the process of rain-fed wheat cultivation in the environment, the potential of indentifying suitable areas for growing this precious plant were provided.