Dynamic Roughness Modeling of Seasonal Vegetation Effect: Case Study of the Nanakita River

Hydraulic models of rivers are essential for vulnerability assessment in disaster management. This study simulates the 2019 Typhoon Hagibis at Nanakita River using a dynamic roughness model. The model estimates river on pixel level from relationship between Manning coefficient and degree submergence vegetation. is defined as ratio water depth to plant height. After validating model, effect vegetation different seasons April 2020 March 2021 was assessed. area height were obtained unmanned aerial vehicle photogrammetry. showed that profile increased by 7.03% average. seasonal observed, revealing strong correlation variations conditions profile. approach may help mitigate flood damage indicating factors can increase risk flooding.