Flood Risk Assessment of Kanhan River Using HEC-RAS and QGIS

Abstract

Floods are among the most destructive natural hazards, threatening lives, infrastructure, and economies. The Kanhan River in Maharashtra, a tributary of the Wainganga, experiences recurrent flooding due to monsoonal rains, unregulated floodplain development, and land use changes. This study conducts a flood risk assessment using Geographic Information Systems (QGIS) and the Hydrologic Engineering Center’s River Analysis System (HEC RAS). High resolution DEMs, LULC data, rainfall records, and river cross sections were processed in QGIS to generate inputs for hydraulic modeling. HEC RAS simulated unsteady flows for multiple return periods, with outputs integrated into QGIS for floodplain mapping. The combined approach enabled spatial visualization of inundation extents, depths, and velocities, highlighting vulnerable zones. The resulting hydraulic model has 0.4036% error which provide actionable insights for disaster management, including early warning systems, embankment reinforcement, and land use regulation. This integrated framework demonstrates the value of geospatial and hydraulic tools in enhancing resilience and guiding flood mitigation strategies in data scarce regions.

Introduction

This project focuses on flood risk assessment of the Kanhan River in Maharashtra using an integrated QGIS and HEC-RAS approach. The study is motivated by recurring monsoon flooding, rapid urbanization, riverbank encroachment, and reduced flood-carrying capacity, particularly in low-lying and densely populated areas.

Main Aim

The main aim is to map and assess flood-prone areas along the Kanhan River by combining GIS-based spatial analysis with hydraulic modelling. QGIS is used for terrain analysis, spatial processing, and flood mapping, while HEC-RAS is used to simulate river flow and flood inundation.

Study Area

The research focuses on the Kanhan River stretch between Saoner and Kamptee in Nagpur district, Maharashtra, approximately between 21.3–21.5°N and 78.8–79.2°E. The region contains agricultural areas, urban settlements, industrial zones, and low-lying riverbanks. Heavy southwest monsoon rainfall from June to September increases the likelihood of flooding.

Objectives

The study aims to:

• Develop a comprehensive flood-risk model using HEC-RAS and QGIS.
• Identify flood-prone areas and estimate inundation extent.
• Use Digital Elevation Models (DEMs) and river geometry to delineate floodplains.
• Simulate river flow and flooding for different return periods.
• Provide information useful for flood mitigation, planning, and disaster management.

Literature Review

Previous research demonstrates that HEC-RAS combined with GIS is effective for flood modelling and hazard mapping. Studies of the Mutha River, Mert River, Yamuna and other river systems have used hydraulic models to estimate water levels, flow velocities, inundation areas, and infrastructure vulnerability. Research on the Kanhan River has also highlighted its importance for agriculture and industry and the need for better environmental and water-resource management.

Methodology

The proposed workflow involves:

1. Creating a new HEC-RAS project.
2. Importing and processing spatial data through RAS Mapper/QGIS.
3. Defining river geometry and the 2D flow area.
4. Incorporating IMD rainfall data.
5. Creating a rainfall grid for the study basin.
6. Performing unsteady-flow hydraulic analysis.
7. Examining model outputs such as flow hydrographs, outflow, velocity, water-surface elevation, cross-sections, and 3D views.

Results

The HEC-RAS model produces several hydraulic outputs that can be used to evaluate flood conditions, including:

• Flow hydrographs
• Outflow and discharge
• Water-surface elevation
• Flow velocity
• Flood inundation extent
• Longitudinal/profile plots
• 3D/XYZ perspective views
• Volume accumulation
• Cross-sectional and detailed output data

These outputs allow researchers to identify areas that are likely to experience flooding and understand how water moves through the river basin.

Conclusion

The flood risk assessment of the Kanhan River, carried out using HEC-RAS and QGIS, demonstrates a high level of model accuracy with an error percentage of 0.4036%, indicating reliable hydrodynamic simulation and spatial analysis. The integration of DEM data, hydraulic modeling, and GIS-based floodplain mapping provided a comprehensive understanding of potential inundation zones.Results reveal that the study area is predominantly under low flood risk, with limited zones experiencing minor vulnerability. This suggests that while the Kanhan River exhibits seasonal variability, the overall flood hazard remains manageable under current hydrological conditions. Above results can be used for further study of the area for early warning sysyems and future planning.

References

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Copyright

Copyright © 2026 Vaibhavi D. Kharbade, Dr. Shubhada Koranne . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.