The hydrological model of the area is fed by observations from sensors which indicate the soil moisture content as well as current water levels in the surface water and groundwater. The model also receives up-to-date information on precipitation and evaporation from meteorological observations as well as data about the weather forecast, which are supplied by radar images and weather models. Radar makes it possible to estimate precipitation with a high degree of precision and also to forecast the weather even a few hours before a given weather phenomenon occurs. The amount of precipitation forecast by the radar is calibrated with local measurements in order to produce precise estimations. Weather models can gather information from the radar in order to calculate precipitation forecasts over longer time frames (up to fifteen days in advance).
Meteorological measurement tower
However, there is often a great deal of uncertainty when forecasting precipitation. This is why, after being corrected for evaporation, the different calculations are bundled into three possible scenarios: wet, normal and dry (see figure). The effect on future water management is calculated with the hydrological model in order to obtain the average forecast within each scenario. This approach makes it possible to forecast drought as well as flood conditions. Once these have been forecast, the water can be retained in order to build up a reserve or it can be drained in order to create a space for water storage in a timely manner.