Hydrological Forecasting and Real Time Monitoring in Finland: the Watershed Simulation and Forecasting System (wsfs)

A watershed simulation and forecasting system is widely used in Finland for simulation of hydrological cycle and for making real-time forecasts. The system is based on a watershed model. This was based originally on the HBV-model and simulates the hydrological cycle using standard meteorological data. The model simulates the whole land area of Finland, including cross-border watersheds. This is a total of 390,000 km. The model simulates the area at a subbasin level. The area is divided into 6,200 sub-basins. The inputs for the model are precipitation and temperature and the simulated components of hydrological cycle are snow accumulation and melt, soil moisture, evaporation, ground water, runoff and discharges and water levels of main rivers and lakes. The input temperature and precipitation comes from 54 real time temperature observation stations, 179 precipitation observation stations and from the weather radar network, which covers almost all Finland. The data assimilation algorithm of the model updates the simulation by assimilating real time water level and discharge observations from 487 stations together with snow water equivalent observations from 158 stations and satellite data of snow cover area and flood cover area. The model uses ensemble weather forecast from the European Centre for Medium Range weather Forecasting (ECMWF). The hydrological forecast is made by simulating the model with 42 different 10 day weather forecasts after which historical weather data is used to make a hydrological forecast for one year. Out of the 42 hydrological forecasts a mean forecast is selected and together with mean forecast the uncertainty limits of the forecast is shown. Hydrological forecasts for over 1300 rivers and lakes are updated several times a day and provided for the users via public internet pages at www.environment.fi/waterforecast. In the case of serious flood an automatic email warning is sent to flood protection officers.