Abstract

This paper describes the importance of flood mapping in terms of saving downstream agricultural area. Flood can cause high impact on the nearby crops productivity which further affects the country’s economy. The Baur dam has a Culturable Command Area of 31453,6572 hectares. It’s key focus is on describing the importance of Manning’s roughness value in dam breach modelling and shows it’s bad impact on downstream areas of dam. In this work hypothetical breach modelling of Baur dam is performed by using Hydrologic Engineer’s Centre- River Analysis System (HEC-RAS). Details about study area, breach parameters, modelling procedure, and outflow flood values are also described in this paper. Flow hydrographs are plotted at different Manning’s roughness value for the two populated downstream areas of dam and it has been observed from results that as roughness value increases flow decreases which justifies Manning’s theory. As a Final result Inundation maps are plotted with the detail of inundated area values for different Manning’s values so that the effect of roughness can be analysed numerically on study area. The Manning’s roughness value of 0.030 causes 37.75km² inundated area in the downstream of dam.¹

Keywords

dam breach analysis, HEC-RAS, Inundation map, manning’s theory, roughness parameter