EFAS collects near real-time water level and river discharge observations to display national/regional threshold exceedances. Furthermore, EFAS provides a number of hydrological monitoring products based on LISFLOOD simulations driven by observed meteorological input.
European wide, observation-based flood monitoring
CEMS Hydrological Data Collection Centre collects near real-time water level and river discharge observations including, where available, the national/regional thresholds from a large number of data providers. The information is displayed in the “National flood monitoring” layer in the EFAS map viewer, with gauging stations exceeding their national/regional thresholds being highlighted. Note that gauging station density might not be the same as at the national/regional level and that, depending on the data provider, a different number of threshold levels might exist. The monitoring of flood extent for specific events based on satellite data is available in the rapid mapping component of the CEMS.
Gridded meteorological maps
To calculate the flood forecasts EFAS needs the hydrological initial conditions for LISFLOOD which are derived from forcing LISFLOOD with gridded, near real-time meteorological observations. A large-number of in-situ meteorological data is collected from various data providers and interpolated to a regular grid. The interpolated grids for daily accumulated precipitation and daily average temperature are available in the map viewer and are important for verifying the quality of the initial conditions for the hydrological model. Furthermore, a 24-hour accumulated observed precipitation information based on SYNOP stations is also available.
Soil moisture and snow water equivalent
To support the interpretation of the flood forecasts EFAS also displays two key hydrological variables, soil moisture and snow water equivalent, that might trigger or increase the risk of flooding. These maps are simulated using near real-time interpolated meteorological observations to run LISFLOOD and are also used as initial conditions for the flood forecasts. For both hydrological variables, soil moisture and snow water equivalent, their respective anomalies are calculated to compare the simulations with the “normal” situation. Where available, the user can also compare these maps with values derived from satellite observations.