HERA: a high-resolution pan-European hydrological reanalysis (1951-2020)

The HERA high-resolution pan-European hydrological reanalysis (1951-2020) dataset is the result of a joint effort between the JRC and PIK to produce a long term hydrological reanalysis with downscaled and bias-corrected climate reanalysis (ERA5-land) and dynamic socioeconomic inputs. It includes maps of climate variables (evaporation, evapotranspiration, precipitation, temperature), dynamic socioeconomic inputs (land use, water demand, reservoir maps) required for hydrological modelling with LISFLOOD and river discharge with European extent at 1 arc minute (~1.5 km) grid resolution and 6-hourly time step. The dataset builds on recent development within the European Flood Awareness System (EFAS) associated to the EFAS v5.0 reanalysis (http://data.europa.eu/89h/76b4b9de-a5c6-4344-8d88-c4bed7752ce3), notably the LISFLOOD static and parameters maps for Europe (http://data.europa.eu/89h/f572c443-7466-4adf-87aa-c0847a169f23) and the EMO (European Meteorological Observations) dataset (http://data.europa.eu/89h/0bd84be4-cec8-4180-97a6-8b3adaac4d26). HERA also benefits from major improvements to the open-source hydrological model LISFLOOD and a new model calibration. Furthermore, for ungauged catchments, a parameter regionalization was performed transferring parameter sets from donor catchments based on spatial and climatological proximity to ensure the best possible simulation of river flows for all catchments in the European domain. Along with improved resolution and modelling performances, the length of the modelled period (70 years) and the inclusion of dynamic socioeconomic conditions enables the analysis of hydrological dynamics related to extremes, human influences, and climate change at a continental scale while keeping local relevance. Detailed technical information on the dataset can be found in the associated scientific article (https://essd.copernicus.org/articles/17/293/2025/essd-17-293-2025.html).

---------- Update 29-07-2025 - VERSION 2.0 ----------

A new set of yearly river discharge files has been generated with a

correction implemented in the water demand module:

to prevent spurious increases of river discharge

triggered by increased water demand from all sectors, we set the return flow from groundwater abstraction to the river network to

0% instead of the initial value (from 75 to 80% depending sectors). This modification is comparable to the one that will be

will be implemented in the next release of OS LISFLOOD (https://github.com/ec-jrc/lisflood-code/commit/1a32c02534feca45e801a2c14b26d62a148e3288).