Integrated slope stability assessment of earthen canals under seismic loading using pseudostatic analysis and vetiver grass reinforcement

Earthen canals in seismically active regions face combined hydraulic and earthquake loading that can compromise slope stability. This study evaluates the effectiveness of vetiver grass as a bioengineering reinforcement through Pseudostatic slope stability analysis of a critical section (IT3) of the Khush Tepa Canal using the Morgenstern-Price limit equilibrium method. Steady-state, rapid drawdown, and seismic scenarios were systematically assessed to quantify their influence on slope performance and reinforcement benefits. Results show that the canal is stable under steady-state conditions (FoS = 2.11), while seismic loading reduces stability (FoS = 1.25, a 40.8% reduction), and rapid drawdown represents the most critical scenario (FoS = 1.10). Vetiver grass reinforcement substantially improves levee stability, increasing the FoS from 1.93 to 2.37 (a 22.8% gain) under static conditions. This improvement is attributed to increased apparent cohesion from the dense root network, which constrains failure surfaces to shallower depths and prevents deep rotational sliding. These quantitative improvements demonstrate that vetiver grass provides measurable structural reinforcement. The findings support integrating nature-based solutions into earthen canal design to enhance both hydraulic and seismic resilience in earthquake-prone regions.