Fig. 15.24 Variation of u with σ
(ii) Partly-filled Reservoir Condition Soon after the construction of an embankment dam, it takes a few seasons to fill the reservoir. This means that the dam will experience different amounts of pore pressures at different times depending upon the reservoir level. Since the upstream slope would not be fully covered with water during partly-filled reservoir condition, it needs to be examined for stability for various reservoir levels ranging from one-third to two-thirds the height of the full reservoir head, and the minimum factor of safety is worked out.