| Abstract: | Summary Forecasts of the discharge of the Rhine at Basel have been studied in Zurich since 1954. In this programme have cooperated hydro-power companies of Switzerland, Germany and France, French shipping-firms, and the Dutch water management authorities. For the Netherlands the forecast of the summer yield of the Rhine is of great concern, since it is the main resource of fresh water. The studies have resulted in: — since 1955, annual forecasts of the yield from snowmelt for periods of one to eight months beginning with March, and monthly and bi-monthly forecasts in winter — since 1960, forecasts issued 2 to 5 times per week for the next three days, from October to March. The forecast method is the least squares multiple regression, based on the observations of more than 50 years. For the short term forecasts, the significant predictors are discharge and rainfall, eventually the snow cover percentage on the Swiss midland plateau. The largest errors of forecast were encountered in thawing conditions. Meteorological forecasts are provided by the Swiss Meteorological Institute. For the long range forecasts, the alpine snow pack (in practice represented by the cumulative winter precipitations) and the levels of the Swiss lakes play an important role. The forecasts are used by the hydro-power plants in their operation programmes for maintenance planning, and for proper timing of construction work. In the future, the probability graduation of these forecasts will also be introduced in the optimisation of power production according to the methods of operations research. |
