The calculation of pore water pressure distribution in a slope partially submerged and subjected to a drawdown is analyzed in this chapter. Drawdown phenomenon is a critical situation for the stability of slopes of earth dams and bank rivers affected by variations of water level. The prediction of pore water pressure in two earth dams subjected to a drawdown event under different calculation hypothesis highlight that classical flow methods of analysis may overestimate or underestimate pore water pressures depending on several external condition and material properties. In particular, an instrumented dam is simulated and calculated results can be compared with field measurements. Finally, in the chapter, an incipient landslide (40 Mm3) in the left margin of a reservoir triggered by a drawdown is presented and analyzed.