Knowledge of hydrological extreme values provides an essential basis for the classification of extreme events, the planning of hydrological engineering measures, the optimal use of water resources, the management of facilities, and the protection of waterbodies.

Data on flood and low-flow discharges is stored by the Hydrology Division in special databases, which facilitate the provision of information on current events and the preparation of flood and low-flow data and statistics. On the basis of the values calculated, floods and low-flow events can be placed in a broader context. The FOEN analyses extreme events and issues reports on their causes and consequences, e.g. the flooding of 1999 and 2005, or the drought that occurred in the summer of 2003. The data is also used in the preparation of thematic maps published in the Hydrological Atlas of Switzerland (HADES).