This study is focused on the stretch of river Bhima which is the major left bank tributary of river Krishna, that majorly affects the cultivation area, commercial areas, and population in the vicinity of the bank. Therefore, in this study, an attempt is made to develop a model that will facilitate in creating flood protection measures and plans for management during flood emergencies. With the help of accurate flood-maps the affected areas alongside the river can be easily spotted. For the flood inundation modeling of the reach the annual maximum discharge data of 60 years (1965–2024) for Takli Gauge and Discharge (G&D) are analyzed and forecasted for the return period of 100, 500, and 1000 years. Flood frequency analysis is carried out using well known probability distributions to obtain the extreme flow for different return periods. Of all, Gumbel’s distribution is fitting best with discharge data of Takli G&D when tested using Kolmogorov–Smirnov (KS) test with the lowest maximum deviation ( \({D}_{max})\) of 0.083 and attained a significance level (α) of 80.60%. Flood inundation modeling is done in the HEC-RAS 1D steady model using the peak flood discharge as steady flow data under various scenarios of different profile of cross-sections across the stretch. The analysis shows that with increase in the cross-section the flood pulse traveling away from the bank in minor tributaries increases with overall increase in the inundation area. The chief objective of this study is to determine the optimum cross-section profile to accurately model and map the flood spread along the floodplain.