What is the status of rivers and lakes in Switzerland? ( FOEN)
The map shows the current Swissriver discharges and lake water levels compared with the monthly percentiles of the long term hourly averages (expressed in percentiles).
The percentiles are calculated every month based on the «long term series» of hourly average measurements. The hourly averages from the start of measurements to date are compiled separately for each month, The percentile defines what proportion of the data is higher or lower than a specific limit. A flow at the 95% percentile means that 95% of the flows measured in the month in question are below that threshold (only 5% are above it).
Link to the map: map.geo.admin.ch