Investigating the Effect of Manning Coefficient in Flood Modeling: A Case Study of the Hron River in East Slovakia

Floods are one of the major hazards that negatively affect human life. Computer-aided approaches are crucial to simulate flood events and minimize their negative effects on people's lives and properties. The flood simulation based on fluid flow calculations could help to understand the extensions and depth of previous floods, and it can be helpful to manage future plans regarding flood protection and mitigation scenarios. However, sensitive flood modeling is based on the accuracy of the data used, such as topography, discharge, precipitation, roughness coefficient, etc. In this study, the effect of the Manning Coefficient in 2D flood modeling was tested by using different constant Manning values. Additionally, a Manning Layer was defined based on the land cover data in the 2D model. Land cover data was clipped for the specified region. All models were created using HEC-RAS software. A part of the Hron River, Slovakia, was chosen as the study area. The location of the chosen river part is between the Ziar Nad Hronom and Ladomerska Vieska. The chosen area is a rapidly developing part of Slovakia. The generated models were tested under the same conditions: the same terrain model, the same geometry, and the same discharge values were used in each model. The results of each model were analyzed by using the flood extensions and depth information of the models. According to the outputs of the models, it is seen that the Manning Coefficient is one of the key parameters of 2D flood modeling, and the correct definition of the roughness increases the reliability of the flood models that could help in providing more adequate strategies for flood protection and mitigation. The study is in line with the goal of loss of flood-induced life and economic losses under the heading of sustainable cities and communities within the scope of SDG. In addition, this study has the potential to indirectly contribute to the SDG targets under the title of climate action, “strengthening the resistance and compliance capacity of climate-induced disasters”.