WP2: Scaling of hydrological models
Often, assessments of climate change impacts are required at a local scale. Hence, there is a need for downscaling of the regional hydrological model to the local scale. Flexible numerical grids are required for accurate descriptions of the interaction between streams and groundwater, the flow near large well fields, the flow in cities and for the resolution of complex geological units (e.g. faults, buried valleys, enclosed pinch-outs). Several methods for grid refinement that provide a flexible technique for changing the resolution of the mesh are currently available, including nested grids, local model builder and finite element techniques. The present project will instead focus on development of a new approach exploiting the potential within OpenMI to develop dynamic coupling between local and regional models. This approach will be evaluated against the traditional refinement methods.
The analyses in this work package will be based on extensive case studies of geology and groundwater flow in areas with complex geology. For each study the national DK hydrological model will be used as an already existing regional scale groundwater model. In addition, the case studies will be selected so that comprehensive geological and geophysical data are available for a smaller (local scale) geologically complex area. Alternative conceptual geological models will be developed for the smaller area using various geological modelling tools, e.g. MIKE Geomodel,
The alternative conceptual geological models will vary from layer based, over pixel based, to very complex models. Some of these models can be built into finite difference based as well as into finite element based groundwater models; others can best be built into finite element based models. The existing regional groundwater model is either refined in the local area or tied to a refined local model, and each of the alternative local conceptual geological models is transferred to the local-scale groundwater model. The alternative groundwater models are used to simulate for example groundwater flow paths and well head protection zones within the local area. For the various cases it is thus investigated to what extent the simulation results are sensitive to the choice of conceptual geological model and to the choice of numerical flow and transport simulation technique. On this basis guidelines are given on how to develop conceptual geological models for geologically complex areas, and on how to numerically simulate groundwater flow and transport in such areas.
Aarhus University, Department of Earth Sciences, is in charge of this work package.
Contact: Steen Christensen,
Contact: Mike Butts
Complex geology (PhD project)
Contact: Troels Norvin Vilhelmsen