Quantifying riverbank and soil erosion risks in the upper Ghaghara river basin and their implications for flood management

TL;DR

This study assesses erosion and flood risks in the Upper Ghaghara River basin to guide better flood management and ecosystem sustainability.

Contribution

The study integrates spatio-temporal erosion analysis with flood susceptibility modeling to inform multi-hazard management strategies.

Findings

Right bank erosion rates are significantly higher than left bank erosion in the Upper Ghaghara River basin.

High soil erosion rates coincide with active bank migration areas, indicating interconnected geomorphic processes.

30% of the basin is classified as high to very high flood risk, supported by flood inundation analysis.

Abstract

Riverbank erosion, soil loss, and flooding are interrelated processes that critically influence river morphology, sediment dynamics, and floodplain stability. Understanding their spatial and temporal interactions is essential for effective watershed management. This study evaluates the spatio-temporal patterns of river bank change along the Upper Ghaghara River basin and investigates their relationship with regional soil erosion risk and flood susceptibility. River bank dynamics were quantified using the Digital Shoreline Analysis System (DSAS v. 6.0) applied to multi-decadal satellite imagery from 1991 to 2024, calculating key metrics including End Point Rate (EPR), Net Shoreline Movement (NSM), and Shoreline Change Envelope (SCE). Soil erosion risk was modeled using the Revised Universal Soil Loss Equation (RUSLE), incorporating rainfall erosivity, soil erodibility, slope, vegetation cover, and conservation practices, while flood susceptibility was assessed by integrating multiple hydro-geomorphic factors using the Analytic Hierarchy Process (AHP). Results indicate pronounced erosion along the right bank with an average EPR of − 20.76 m/yr and an average NSM retreat of − 687.4 m, compared to − 5.53 m/yr and − 176.7 m, respectively, on the left bank. Approximately 62.7% of right bank transects and 57.5% of left bank transects exhibit significant erosion. Soil erosion rates exceed 40 t/ha/yr in high-risk zones of the basin spatially coincident with active bank migration areas. Flood susceptibility mapping identifies 30% of the basin under high to very high flood risk, corroborated by 2022 pre- and post-flood inundation analyses showing extensive floodplain coverage. These findings highlight the synergistic impact of bank erosion, upland sediment supply, and flooding on river corridor dynamics. The integrated assessment underscores the necessity for multi-hazard management strategies to mitigate geomorphic hazards, sustain riverine ecosystems, and enhance socio-economic resilience in this vulnerable basin.

The online version contains supplementary material available at 10.1038/s41598-025-33264-4.

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