Investigating the causes and problems of Zarrinehrood riverbed changes from Karkareh village to Miandoab in the period 1988 to 2019

In order to evaluate the morphology and lateral changes of the river channel, four indices of curvature coefficient, central angle, migration rate and transect were used. Remote Sensing (RS) and Geographic Information System (GIS) techniques were used to extract the duct in different time periods as well as to calculate geomorphic indices. The results show that the indicators used have a lot of spatial and temporal variability along the Zarrinehrood River. In the central angle index of the whole duct in the time periods of 1988, 2003 and 2019, it was equal to 89.9, 91 and 109.2 degrees, respectively, which was a slight increase in the value of the central angle over the past 30 years. In 1988, 2003 and 2019, we are 1.7 in the third period, 1.65 in the second period and 1.81 in the second period, respectively. In the transect method, 472 hectares of land have been destroyed and eroded in the last 30 years. Which is obtained to 15.2 hectares per year. This indicates the diversity of environmental conditions prevailing in the river channel and banks, as well as the transverse dynamics of the Zarrineh River. The morphology of the first interval is mainly in the control of two variables, geology and floods. Indicators and field visits indicate high and very active lateral mobility of the river channel in the second interval. Developed floodplain, erodible sides, abundance of floods, high flow and relatively high slope are among the most important factors affecting the morphological changes of this period. The morphology of the third interval is strongly influenced by sand extraction and canalization operations. The results also show that in recent years the rate of lateral changes of the river channel has decreased in all intervals. This is due to the significant reduction in river discharge.