University of Tabriz Journal of Hydrogeomorphology 2383-3254 2 2 2015 05 22 Determining Factors in the Evolution of Geomorphology Fan and the Basin of Usko Chay Determining Factors in the Evolution of Geomorphology Fan and the Basin of Usko Chay 41 66 3538 FA Journal Article 2014 11 24 The rivers are sensitive to tectonic movements and there is a close relationship between the river landforms and such movements.  Geomorphic indexes are used as tools to specify the new constructions and active workings of such movements. Due to active tectonic movements in Usku Chay’s basin which are visible in the river traces, unconformity fault, and etc. indexes coherent to measurement of active tectonic have been calculated. In this study the indicators such as (SL), index asymmetry (AF), index canal width indicator of the valley floor to its height (VF), the index ratio of width of river floor to altitude (BS) and indicators of the extent of the fan (AF) and SF Fan that shows the relationship between the extent of the fan and a basin were used and the influence in the formation of tectonic fans, (the slope and spread) was calculated. All these indexes were extracted from geology and topography maps and were then entered to GIS to calculate the indicators and were categorized as high, medium and low tectonic activities. The results obtained from the analysis of topographic data, geomorphological evidence from field observations, and the values obtained from the geomorphic indicators, and survey evidence suggests that are neo tectonic activity in the basin and the area classified in Class LAT depicts a high activity, and coins are formed in the active tectonic basin. Quantitative values obtained from geomorphic indicators are confirmed by regional geomorphic signifiers. The rivers are sensitive to tectonic movements and there is a close relationship between the river landforms and such movements.  Geomorphic indexes are used as tools to specify the new constructions and active workings of such movements. Due to active tectonic movements in Usku Chay’s basin which are visible in the river traces, unconformity fault, and etc. indexes coherent to measurement of active tectonic have been calculated. In this study the indicators such as (SL), index asymmetry (AF), index canal width indicator of the valley floor to its height (VF), the index ratio of width of river floor to altitude (BS) and indicators of the extent of the fan (AF) and SF Fan that shows the relationship between the extent of the fan and a basin were used and the influence in the formation of tectonic fans, (the slope and spread) was calculated. All these indexes were extracted from geology and topography maps and were then entered to GIS to calculate the indicators and were categorized as high, medium and low tectonic activities. The results obtained from the analysis of topographic data, geomorphological evidence from field observations, and the values obtained from the geomorphic indicators, and survey evidence suggests that are neo tectonic activity in the basin and the area classified in Class LAT depicts a high activity, and coins are formed in the active tectonic basin. Quantitative values obtained from geomorphic indicators are confirmed by regional geomorphic signifiers. https://hyd.tabrizu.ac.ir/article_3538_6a58aa8ae5995d3693b33abd86eabcd5.pdf