Determination of flood potential effective factors in hydrological homogenous regions, Case study: Se-Hezar and Do-Hezar watersheds (Cheshmehkileh), Tonekabon

In recent years, due to the frequent floods in the Se-Hezar and Do-Hezar watersheds of Tonekabon (Cheshmehkileh) and subsequent flood damage in the Tonekabon urban area, it is necessary to pay attention to the zoning of flood hazards especially in the main river surrounding lands at studied area. In the present study, using a system-based approach in a watershed (interconnection of all elements present in the watershed), hydrological homologous regions were identified using cluster analysis based on topographic, geological, physiographic, land cover and hydroclimate features. By doing this step, three hydrological homogeneous regions were determined in the watershed. In the second step, flood potential was zoned in hydrological homogeneous regions using the criteria of topography, geology, land cover and hydro-climate and applying fuzzy hierarchical analysis method. According to the flood potential zoning map, the most extent of study area has a moderate flood level. Finally, factor analysis was used to determine the most important factors affecting the flood potential of the watershed. The results of factor analysis indicate that 100% of the variance is justified in hydrological homogeneous regions based on 2 factors and 20 variables, while the second factor with eigenvalues 0.995 justifies 51.1% of the total variance. In the second factor, the parameters of area, main river length, drainage network density, branching ratio, Horton coefficient, concentration time and forest, range, and high permeability lands percentage have shown high correlation (more than 0.75) with flood potential of the watershed which the parameter of area is the most important effective factor in the flood potential of hydrological homogenous regions.