The evaluation and assessment of bank erosion risk using BANCS model: a case study in northern Iran, Waz River, Mazandaran

The erosion phenomenon and sediment transport are the most important hydrodynamic processes that effect watersheds, rivers, coasts, ports, dams, bridges, roads, farms, and civil facilities. Waz is one of the main rivers on the northern slope of Alborz in Mazandaran province. This river has a morphological dynamic behavior and affected by various factors including geology, slope, land-use, and the condition of hydraulic flow. The aim of this study was to assessing the bank of Waz River stability using BANCS model, which is include NBS and BEHI indexes. To assessing the rate of bank erosion in the Waz River, in a three kilometer interval, eight cross-section were selected using field impression and mapping the parameters e.g. side height and angle, bank-full width, bank-full average depth, the maximum average-depth of bank in bank-full, the curvature radius, and bank material based on NBS and BEHI models. Regarding the results for each cross-section based on bank erosion risk index, near bank shear stress and comparing with field surveys, the banks with more risk of bank erosion and more stable banks were determined. Besides, comparing the results obtained from BEHI and NBS models with field surveys showing more efficiency of BEHI model for the Waz River.