Dam-Break Flood Waves Analysis and The Floodplain Mapping using Mathematical Model (Case Study: Vanyar Dam)

In this research, the dam break problem has been presented from the viewpoints of importance, mechanism, spatial and temporal analyses as well as governing mathematical equations. For this purpose, the output hydrographs of the Vanyar dam site have been computed by breach model under a fictitious dam break scenario (overtopping) as the first step. In the next step, the output hydrographs have been routed through the downstream river by using HEC-RAS model. Then water levels and wave front arrival times have been computed at all cross sections. Finally the obtained results have been imposed to Geographic Information Systems in order to obtain the presentation of the results to develop floodplain maps. Considering the obtained results, the output hydrograph’s shapes have moderate slope, because gradually breach mechanism occurs in the dam in this scenario. Furthermore, the power of the flood is considerably decreased without any significant financial damages under the geomorphological and topographical downstream conditions of the river close to the dam site. However, the study shows that some villages and installations in the downstream may be prone with some minor damages. Also the maximum flood plain and wave front arrival time at the downstream have been calculated.