Rivers are unstable environments which under the natural and human factors influence, change their direction and pattern. These changes are not the same in all parts of the river, and depending on the factors affecting it, occurs the different levels of change. The study area is part of the Bashar river which contains three intervals between nations Blvd. Yasouj to that part of the river town Mithraian welding is an interval. The purpose of this study is investigating and detecting river bed geometry changes in the period being studied. In this study, the factors affecting on river bed geometry changes and the rate of change and its impact on development of the Yasooj were investigated. The method of this research is a comparative analysis which using direct and indirect observations and images and maps, the type and extent of geometry changes in waterways is studied and between the four periods, and four spatial interval is analyzed.
Also, the 1335 aerial photography, 1362 aerial photography, images of IRS in 1384 and 1393 Google earth images have been used. Accordingly, the riverbed in four periods digitalized in Arc Gis. And then, the riverbed changes, and river location displacement in the river examined in each period, and every four intervals.The results of the data analysis, satellite imagery and aerial photographs indicated that River beach in the study area has been relocating. According to data the first period and the fourth period variability is greater than the other intervals. During the surveyed period at intervals of choice for the most influential factor in changes in morphology, land use, geology and tectonics of the track bed had been. As a result, any type of urban development around the river requires River changes management in the intervals being studied.
Keywords: the river geomorphology, Bashar River, geometric change, Yasooj Urban sustainable development.