Effects of sediment transport on 1-D and 2-D hydrodynamic modeling and flood inundation

Önder, Görkem
In this study, effects of river bed changes on flood inundation are analysed with 1D and 2D coupled hydrodynamic and sediment transport modeling. In order to select the best set of methods depending on qualitative and quantitative indicators, sensitivity of the variables affecting sediment transport processes are presented. Methodology that includes sensitivity analyses of sediment transport processes and real event analyses is implemented for Terme River. Sensitivity analyses are done with 1D modeling by using MIKE 11 HD and MIKE 11 ST software. In these analyses hydrographs having different return periods are used. Effects of sediment transport on flooding are considered with 2D modeling by using MIKE 21 HD and MIKE 21 ST software. Engelund-Fredsoe method with suitable bed level update method is determined as the best method for the study area. Morphological changes and the effect of morphology on hydrodynamics are presented with three real flood events by using 1D modeling. 2D hydrodynamic and sediment transport models are implemented for real flood event occurred in 2014 to examine the effects of morphological changes and grain size diameter on flood inundation. Results of the study show that sediment transport thus morphological changes affect hydrodynamics and flood inundation. In addition, bed level update method and grain size diameter dramatically affect hydrodynamics and flood occurrence. Flood inundation area obtained from coupled modeling decreases compared to pure hydrodynamic modeling for the study area. Analyses show that 2D models give more precise results for bed level changes and sediment transport processes than 1D models but they still demand too much computation time.