The draw down of reservoirs can significantly affect the stability of upstream slopes of earth dams. This is due to the
removal of the balancing hydraulic forces acting on the dams and the undrained condition within the upstream slope
soils. In such scenarios, the stability of the slopes can be influenced by a range of factors including drawdown rates,
slope inclination and soil properties. This paper investigates the effects of drawdown rate, saturated hydraulic
conductivity and unsaturated shear strength of dam materials on the stability of the upstream slope of an earth dam. In
this study, the analysis of pore-water pressure changes within the upstream slope during reservoir drawdown was
coupled with the slope stability analysis using the general limit equilibrium method. The results of the analysis
suggested that a decrease in the reservoir water level caused the stability of the upstream slope to decrease. The dam
embankment constructed with highly permeable soil was found to be more stable during drawdown scenarios,
compared to others. Further, lower drawdown rates resulted in a higher safety factor for the upstream slope. Also, the
safety factor of the slope calculated using saturated shear strength properties of the dam materials was slightly higher
than that calculated using unsaturated shear strength properties. In general, for all the scenarios analysed, the lowest
safety factor was found to be at the reservoir water level of about 2/3 of drawdown regime.