Investigating the lateral erosion of Darehroud river and its classification using Rasgen model (Case study: Horand city - East Azerbaijan)

Riverbank erosion is a hydraulic process in which the tensile force of flowing water causes the separation of soil particles from the bank. River channel changes, bank erosion, and bank sedimentation are natural processes in alluvial rivers that can lead to the destruction of surrounding agricultural lands and damage to human infrastructure near the river.In this research, the Rasgen model (Levels 1, 2, and 3) was used to evaluate the condition of the Darehroud River and measure the extent of bank erosion. Level 1 was utilized to determine the channel type after calculating the river slope in the study area. Based on the slopes obtained from different sections, field observations of the river's cross-sections, and its planform during field studies, and considering the river classification system based on slope in Level 1 of Rasgen, the examined sections were categorized into Groups B and A.For this study, six sections from Gavlan village to Laqan village, spanning a length of 5 kilometers, were selected. After determining the river classification in Levels 1 and 2, the conditions of the Darehroud River were evaluated using Level 3 of the Rasgen system. The results indicate that sections 2, 5, and 6 (Group 4B) with total scores of 91, 85, and 111, respectively, and section 4A with a score of 87 are in a weak and unstable condition. In contrast, sections 1 and 3 (Type 4A) with scores of 91 and 87, respectively, are in a good and stable condition.Overall, the classification of the Darehroud River based on the Rasgen model (Levels 1, 2, and 3) provides a logical assessment that delivers more detailed and accurate information for river management applications.