Deltares, Wageningen University: New Approach to Hydrological Modelling

Water managers are continuously making decisions to guarantee water safety. These decisions relate to the short term, for example ongoing droughts or, precisely, when there is a risk of flooding. But they can also affect the long term given the more extreme events caused by climate change.

All these decisions have one thing in common: they are often grounded on results from hydrological models.

Researchers from Deltares and Wageningen University studied a new design for a model of this kind for the Rhine. The results were published recently in the AGU journal ‘Water Resources Research’.

Designing a model like this and setting it up for a specific river basin involves a lot of challenges. In particular, setting up the parameters of the model is often thought to be a difficulty. Parameters in a hydrological model are used to link the behavior of the model to that of the river for which the model is set up.

Current hydrological models are spatially distributed, which means that they divide the river basin into small cells of, for example, one square kilometre. A set of parameters are in place for each cell.

“Until now, the parameter values were determined using calibration methods that were applied to all the model parameters. However, with the ongoing increase in spatial resolution that we use to model river basins, this approach is becoming an unattainable multidimensional challenge,” said Deltares.

In this study, the parameters of a hydrological model were estimated using experimental functions from the literature that have been derived in laboratories worldwide.

The functions use freely available information about the locality – such as soil, vegetation and land use data – to estimate physical properties.