Reading high and low water correctly

A flood occurs when a catchment receives more water than soils, lakes and channels can temporarily absorb or drain. Triggers can be long-lasting rain, short intense thunderstorms, snowmelt or a combination of saturated soils and further precipitation.

Small steep streams often respond within a short time. Large lakes dampen inflow peaks but can rise over days under sustained load. Downstream of a lake a wave usually appears later and smoothed; regulation and power plants can change the development further.

Low water often develops during longer dry periods. Missing precipitation, high evaporation and little snow or groundwater inflow lower levels and discharge. High water temperatures can increase the ecological stress at the same time.

A low seasonal value is not unusual on every water body. In the alpine winter discharge can be naturally low, while lakes respond differently through regulation or storage. The comparison must therefore fit the season and the station.

The deviation from the median describes whether a value is rather high or low for the given period. The trend describes the direction of movement. An official warning level, by contrast, assesses a possible danger using water-body specific thresholds and additional expert information. None of these statements can replace the other two.

A lake can be well above its seasonal median and still be far from a flood limit. Conversely, a quickly rising small stream can become critical even without a long reference series. Seepegel therefore avoids a blanket hazard colour for all water bodies.

Check the timestamp and trend first. Then open the official source named for the station and heed warnings from federal, cantonal and municipal authorities and local emergency services. Do not enter flooded paths or shorelines and keep your distance from fast-flowing water. Personal Seepegel alerts concern user-selected conditions; they do not replace official warnings or emergency services.