<![CDATA[Slope instability along reservoir banks is an important but often overlooked source of sediment entering reservoirs during water-level fluctuations. Previous sedimentation assessments in Keuliling Reservoir mainly considered watershed erosion and did not explicitly quantify the contribution of reservoir-bank slope failures. This study investigates the potential sediment contribution from unstable reservoir slopes induced by water-level drawdown. Field observations, soil sampling, and laboratory shear tests were conducted in three landslide-prone zones around the Keuliling Reservoir, Aceh Province. Slope stability was evaluated using a limit equilibrium framework under different water-level drawdown scenarios ranging from 0.2 to 2.4 m. The results indicate that slope stability decreases significantly as water levels decline. Zones A and C exhibit unstable conditions with average safety factors of 0.52 and 0.99, respectively, while Zone B remains relatively stable with an average safety factor of 2.92. Potential sediment contribution from unstable slopes was estimated using a sediment transport approximation adapted from classical bed-load theory to represent possible mobilized material during slope failure. The analysis shows that reservoir drawdown can substantially increase slope instability and may contribute additional sediment to the reservoir storage. These findings highlight the importance of incorporating reservoir-bank instability into sediment management, operational decision-making, and disaster risk reduction strategies in reservoir systems. The results provide useful insights for reservoir operation planning, particularly in establishing safer drawdown rates and slope monitoring strategies.]]>
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