General considerations

Practically all reservoirs constructed all over the world show, to some extent, water losses of variable importance. In spite of the studies commonly carried out before and during dam construction, it is not always possible to predict precisely the hydraulic behaviour of the dam body and/or the geological formations in the vicinity of the dam site. Therefore, when a dam is constructed, a certain probability of leakage and/or seepage is assumed. In some instances, the rate of leakage or seepage is accepted as long as there is no concern from the safety point of view. However, it is a difficult task to assess the risks and associated consequences derived from excessive leakage and seepage.