Large scale, high-resolution hydrological modelling

A large-scale hydrological model is a model application set up and used for large regions, encompassing many river basins, crossing regional and international boundaries, and a number of different geophysical and climatic zones. Widespread availability of regional and global databases as well as increases in computer processing speeds introduce the potential to setup and use traditional high-resolution hydrological and nutrient transport models over multi-basin scales.

The large-scale hydrological models developed at SMHI use the spatial distributions of topography, soils, vegetation and nutrient inputs to predict spatially-varying catchment behaviour.

Homogenous model for transboundary waters

Uniform input data from readily available global databases and a uniform approach to model application development and calibration are used over the entire modelled region. This ensures a homogenous model application, for which transboundary rivers and indeed all rivers and streams are treated equally. A high spatial resolution ensures a sufficiently high-resolution description of topography, land-uses, nutrient inputs and soil-types as well as the hydrometeorological forcing, which can vary significantly, particularly in mountainous regions and where convective rainfall events are significant.

Developed models

Examples of large-scale, high-resolution models we have developed at SMHI include:

Europe: E-HYPE
Baltic Sea catchment area: BALT-HYPE
Sweden: S-HYPE
La Plata Basin in South America: LPB-HYPE 
Niger river: Niger-HYPE,
Arctic Ocean catchment area: Arctic-HYPE
India: In-HYPE
Middle East and northern Africa: MENA-HYPE

A summary of these models can be found at Model systems. The hydrological model HYPE has been used for all systems described above.



Purpose of models

Results from such models can be used for many different purposes. Discharge and nutrient load results along the coastal boundary of the model domain may be used to examine freshwater and nutrient influxes to seas.

Discharge and water quality results at all points with the model domain can be used for characterization of water body status, establishment of environmental goals, planning of remedial measures and development of monitoring strategies for the European Water Framework Directive (WFD).

The models can also be used to describe variability in hydrological and nutrient load variables in a present climate, but can also be run using climate model data to predict future conditions.

Tool for set-up new models

The World Hydrological input set-up tool(WHIST), developed here at SMHI can be used to set up the HYPE model in any region by using the global geographic databases for delineation and routing of the model subbasins.

Research challenges

Research challenges specific to large-scale applications of hydrological and nutrient models include:
• Evaluating and correcting gridded precipitation and temperature data for large regions
• Evaluating and improving topographical databases and river routing networks (e.g. HYDRO1K, HYDROSHEDS) for use at varying scales over large regions
• New methods for uniform calibration of distributed models over large regions
• New methods for evaluation/validation of models across many gauging stations and many land-use, soil-types and climatic regions
• Methods for using climate model precipitation and temperature for large-scale hydrological modelling