Following previous wflow user meetings in 2017 (Delft, the Netherlands) and September 2018 (Yogyakarta, Indonesia), the 3rd wflow user meeting took place in November 2018 as part of the Delft Software Days at Deltares, Delft. The program of the day focussed on the presentation of the new wflow 2018.1 release, and included interesting presentations on the use of the wflow framework and hands-on exercises in the afternoon. Around 35 enthusiastic participants joined this successful 3rd edition of the wflow user day.
 

About wflow
The wflow hydrological modelling framework is the Deltares Open Source framework for setting up hydrological models world-wide. The key features of the wflow framework are:

• Open Source - code can be found at: https://github.com/openstreams/wflow
• Fully distributed - grid based
• Multiple hydrological model concepts available, e.g. HBV, SBM, W3RA
• BMI compliant for time-step based coupling with e.g. MODFLOW
• Connected to Delft-FEWS via a wflow adapter

The wflow framework has already been implemented in many countries around the world, along with applications for Operational Forecasting using Delft-FEWS. More information on the wflow framework can be found on https://wflow.readthedocs.io/en/latest/. Questions about the wflow framework or about how to obtain the executables of wflow can be sent to wflow@deltares.nl.

Summary of the wflow user day

Ruben Imhoff from Wageningen University and Research demonstrated how wflow models can be set up  using Pseudo Transfer Functions to come to calibration-free models with seamless large-scale parameter estimations. According to tests for basins in Europe (Rhine) and the USA, the results are very promising, however further research is needed on the estimation of snow and glacier melt related parameters.

Secondly Helene Boisgontier from Deltares,  presented on soil erosion modelling in the Rhine basin, using the wflow framework. The approach which is based  only on open and mostly globally available data,  generates very good results. The main challenge is to solve the issue of finding or generating a good dataset for river width and slope.

Subsequently, Jaap Schellekens from Van der Sat presented his work on satellite derived soil moisture observations and the comparison with soil moisture modelling using the wflow framework. It was shown that soil moisture observations, which in theory can be derived for the whole world, can be a very good proxy for discharge estimations. By combining observations with models like wflow, a system for soil moisture and discharge forecasting could easily be set up.

And last but not least, Albrecht Weerts from Deltares introduced the C3S422Lot1WEnR project, a Copernicus project that uses the Climate Data Store (ECMWF). The wflowframework is used to generate a runoff dataset, based on the new ERA5 meteorological dataset. This runoff dataset will  become available within the Climate Data Stare.

The presentations of the wflow user day can be found online at the site of the Delft Software Days.