Since 1986, the hydrological division of the Swiss Federal Office for the Environment (FOEN) has been establishing discharge forecasts for the Rhine catchment. Since the introduction of FEWS (Flood Early Warning System) in June 2007, the third generation of forecasting systems has been operational. FEWS covers the entire Rhine catchment as far as Basel. It also includes the tributaries of the neighbouring states Austria and Germany. The entire catchment of about 36 000 km² is split up into 62 sub-catchments. A hydrometrical station is located at the outflow of each area.
The forecasting within the FEWS is based on the hydrological model HBV-96, a semi-distributive conceptual precipitation-runoff model. Until the time of forecasting it is fed with the hourly values of the hydrometric monitoring network of the FOEN and some hydrometric stations of the neighbouring states Austria and Germany and of the meteorological stations SwissMetNet of MeteoSchweiz. In the forecasting area it is driven by the weather models COSMO-2, COSMO-7, COSMO-LEPS and EZMWF. During normal runoff, the FOEN publishes on runoff forecasting on working days at about 08.30 a.m. In critical situations, the forecasting rhythm is accelerated and includes weekends and bank holidays. Results are published on the internet as forecasting bulletins. In addition, the forecasting bulletin Rhine-Basel is daily transmitted per fax to navigation on the Rhine and to different forecasting centres along the Rhine.
In addition to runoff forecasting, hydrological bulletins are published on the internet twice a week. They describe the general hydrological situation, meteorological developments and forecast water levels as well as runoff for the days to come.