Flood Risk Management Using HecRAS Model for the Planning of Artificial Levees as a Structural Measure: A Case Study of Upper Sabarmati River Basin, Gujarat, India

Floods are among the most devastating natural phenomena, causing significant loss of life, damage to property and infrastructure, and affecting the socioeconomic conditions of regions and countries worldwide. Several hydraulic models are available for assessing the impact of downstream floods in a river basin based on various topographical, hydrological, and environmental parameters. In this study, we used a simple HecRAS model to plan artificial levees downstream of Dharoi Dam on the banks of the Sabarmati River in Gujarat, India, as a structural measure for controlling floods. We selected a section of the river basin extending 58 km from Dharoi Dam to Dharol Bridge for our hydrological model study. We used a digital elevation model (DEM) of the area to extract topographical and hydrological parameters. We performed HecRAS-1D steady flow analyses using monthly discharge data from 2006 to identify flood risk locations (cross-sections) downstream of the dam. We added artificial levee structural members to these cross-sections in the model and performed steady flow analyses again with levees at critical locations on both sides of the river. Based on the flood inundation map created by the model, we identified six locations for planning levees to prevent flooding in low-lying areas adjacent to the river. Our results indicated that after adding levees at these vulnerable locations, floodwater remained confined to the river channel, helping us plan structural measures for mitigating floods in the study area. This study suggests that HecRAS-1D model can be applied in other flood-prone areas for planning and managing floods considering local geo-environmental and hydrological conditions.