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The Wageningen Lowland Runoff Simulator (WALRUS): a lumped rainfall-runoff model for catchments with shallow groundwater

The Wageningen Lowland Runoff Simulator (WALRUS) is a novel rainfall-runoff model to fill the gap between complex, spatially distributed models which are often used in lowland catchments and simple, parametric (conceptual) models which have mostly been developed for sloping catchments. WALRUS explicitly accounts for processes that are important in lowland areas, notably (1) groundwater-unsaturated zone coupling, (2) wetness-dependent flow routes, (3) groundwater-surface water feedbacks and (4) seepage and surface water supply. WALRUS consists of a coupled groundwater-vadose zone reservoir, a quickflow reservoir and a surface water reservoir. WALRUS is suitable for operational use because it is computationally efficient and numerically stable (achieved with a flexible time step approach). In the open source model code default relations have been implemented, leaving only four parameters which require calibration. For research purposes, these defaults can easily be changed.

WALRUS model structure

Code availability

The WALRUS code is available as an R-package through this GitHub (WALRUS_1.0.tar.gz). If you want to be kept informed about WALRUS developments, please send me an email ( so I can add you to my WALRUS-update-mailing-list. You can also visit this site from time to time of course.

Screenshot of WALRUS in RStudio


WALRUS and its first applications have been published in two peer reviewed, open access, scientific journals:

WALRUS is also part of a PhD thesis:

  • C.C. Brauer (2014): Modelling rainfall-runoff processes in lowland catchments, PhD thesis, Wageningen University, The Netherlands, .

For Dutch water managers and engineers:

  • Claudia Brauer, Paul Torfs, Ryan Teuling en Remko Uijlenhoet (2016): De Wageningen Lowland Runoff Simulator (WALRUS): een snel neerslag-afvoermodel speciaal voor laaglandstroomgebieden, Stromingen, 22:1, 2-18, .

To facilitate application of WALRUS, we wrote a user manual, which is provided in the documentation-folder, together with the two papers.

The WALRUS-publications

Other publications

User contributions

We would like to add a folder to this GitHub with examples of applications from different users, so we can learn from each other. So, if you used WALRUS, we would be very much interested in your results. In addition, if you have comments or points for improvement of the model or the manual, please let me know (email

Locations of catchments where WALRUS has been applied.


WALRUS is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see

WALRUS logo.


The development and publication of WALRUS has been financially supported by the Hydrology and Quantitative Water Management Group of Wageningen University (The Netherlands - and four Dutch water authorities: Water Board Aa and Maas, Water Board De Dommel, Water Board Noorderzijlvest and Water Board Rijn and IJssel.

WALRUS sponsors


The Wageningen Lowland Runoff Simulator: a rainfall-runoff model for catchments with shallow groundwater







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