Hydrodynamic modelling of river training works for protection of group of villages on the left bank of Ramganga River: a case study

Frequent floods in proximity to river floodplains usually threaten settlements, leading to the loss of lives and property. The use of flood modeling is employed for understanding and effectively managing the inherent risks. In this work, the main factor contributing to the reduction of floodplain coverage is the river training works by modification of channel which is least explored for flood mitigation. The study utilized HEC-RAS 6.1.0, for hydrodynamic modelling to simulate the effects of channel modification for flood mitigation along the Ramganga river near Gauriya village (GV) and a cluster of other villages in district Hardoi (U.P.), India. The HEC-RAS model underwent calibration and validation at two distinct flow events and Landsat Imageries. The accuracy assessment involves key factors such as: accurately simulated flooded areas in satellite imagery (A), simulated flood areas absent in satellite imagery (B), and areas not simulated but present in satellite imagery (C). A Manning's coefficient of 0.03 was identified during this process, demonstrating a strong agreement between the simulated and observed flood extents. This study focused on analyzing the impact of channel modifications on flood mitigation in village areas using possible peak discharges: 1000 cumec, 1700 cumec, and 2500 cumec. The findings revealed that at the discharge of 1700 cumec, there was a notable 23.24% reduction in the flood inundation area. Moreover, at the peak discharge of 2500 cumec, a significant reduction was observed. Additionally, there was a satisfactory decrease in depth and velocity impacting the village areas, contributing to effective flood reduction measures. Thus, river training work by introducing a dredged path adds to the protection of villages on the left bank of the river.