1. About

With GLOFRIM it is possible to couple models spatially explicit (that is, on a grid-to-grid basis) and online (that is, on a timestep basis).

Currently, two different coupling strategies can be realized with GLOFRIM, either ‘two-model coupling’ or ‘three-model coupling’. The former allows to couple hydrology to either routing or hydrodynamic model, while the latter represents the full modelling cascade hydrology to routing to hydrodynamics.

_images/couplingScheme.png

Depending on modelling requirements of a study, the coupling scheme can be configured to your liking. After all, not every physical process and the highest level of detail are required to answer a research question. As such, GLOFRIM can be a flexible tool to avoid under- and overfitting of the modelling question.

Furthermore, the fact that GLOFRIM makes use of the BMI technology allows for extending the current modelling cascade with additional (non-)physical models, ever increasing the representation of relevant processes in a consistent manner.

1.1. Supported models

The models currently supported by GLOFRIM are:

1.1.1. Hydrologic models:

  • PCR-GLOBWB: Global water balance model developed at Utrecht University [Sutanudjaja2018] running at 30 or 05 arc-min spatial resolution; water balance computed based on meteorological forcing, humand and industrial water demand and abstractions; solves kinematic wave approximation for discharge simulations

  • WFLOW: modelling suite for distributed hydrological models within the Deltares OpenStreams project [WFLOW_docs]; contains various hydrologic models, amongst others SBM and HBV; runs on a regular grid but grid resolution is variable; also solves kinematic wave approximation for discharge simulations

1.1.2. Routing models:

  • CaMa-Flood: Global routing models designed for fast flood wave propagation simulations; consists of 1D channels plus water balance simulations for floodplains; basin delineation as unit catchments; developed by the University of Tokyo [Yamazaki2011]

1.1.3. Hydrodynamic models:

  • Delft 3D Flexible Mesh: solving the full shallow water equations; model discretizations can be either flexible meshes, unstructured grids or regular grids; supports 1D, 2D, 1D-2D, and 3D modelling; developed by Deltares [Kernkamp2011]

  • LISFLOOD-FP: specifically designed for inundation modelling; solving the local inertia equations; allows for 1D, 2D or sub-grid channel discretizations; model grid is always regular; developed by University of Bristol, School of Geographical Studies [Bates2010]

A slighly more elaborated description of the models can be found in the next chapter and in the referenced articles.

1.2. Possible applications of GLOFRIM

GLOFRIM is a modular tool allowing for a flexible combinations of different hydrologic and hydrodynamic models. Depending on the design of the coupled model, GLOFRIM can be used for applications such as:

  1. Benchmarking of hydrodynamic models: By providing identical spatially varying and explicit hydrologic forcing, the performance of hydrodynamic models can be compared;

  2. Nested modelling: By adding detailed 2D hydrodynamics to large-scale hydrology and routing, inundations can locally be simulated with more accuracy;

  3. Large-scale routing: For large-scale discharge simulations, replacing kinematic wave approximations with routing models increased accuracy while not increasing run time unneccesarily.

GLOFRIM was so far applied and documented in [Hoch2017a], [Hoch2017b], [Hoch2018], and [Hoch2019].