Examining the Physical Development Scenarios of Yasuj City with Emphasis on the Natural Processes

The establishment of an urban settlement, above all, depends on form, natural processes and environmental factors because natural processes have significant role in site selection, distribution, morphology and physical development of the city and sometimes as a positive and time factor act as a preventive factor. Therefore, in this study it is tried to take advantage of the combination of AHP and GIS in explaining the impact of natural processes of physical development of Yasuj based on systematic approach and scenario design. The results indicate that the first scenario (geomorphology) and the third (seismic) show the highest accuracy and the zoning map result is the most suitable result for space expansion in the city of Yasuj. In geomorphology scenario the most suitable area with the accuracy of 60, 8 % index cover 9. 71 sq. km of existing habitat and can be expanded up to 38. 67 sq. kilometers. The best directions of the expansion generally are to West and South West regions. In seismic scenario with the amount of 61. 39 % is the most suitable area with the highest accuracy index and 11. 51 sq. km of the existing habitat are in this area that can be expanded to 52 sq. kilometers. The best directions of the expansion generally are to East, Centre and West of the area of study. As a result, the main controlling physical development factors of the city of Yasuj are natural processes specially the geomorphology and tectonic parameters.