Common problematic aspects of coupling hydrological models with groundwater flow models on the river catchment scale

摘要

Model coupling requires a thorough conceptualisation of the couplingstrategy, including an exact definition of the individual model domains, the"transboundary" processes and the exchange parameters. It is shown here thatin the case of coupling groundwater flow and hydrological models – inparticular on the regional scale – it is very important to find a commondefinition and scale-appropriate process description of groundwater rechargeand baseflow (or "groundwater runoff/discharge") in order to achieve ameaningful representation of the processes that link the unsaturated andsaturated zones and the river network. As such, integration by means ofcoupling established disciplinary models is problematic given that in suchmodels, processes are defined from a purpose-oriented, disciplinaryperspective and are therefore not necessarily consistent with definitions ofthe same process in the model concepts of other disciplines. This articlecontains a general introduction to the requirements and challenges of modelcoupling in Integrated Water Resources Management including a definition ofthe most relevant technical terms, a short description of the commonly usedapproach of model coupling and finally a detailed consideration of the roleof groundwater recharge and baseflow in coupling groundwater models withhydrological models. The conclusions summarize the most relevant problemsrather than giving practical solutions. This paper aims to point out thatworking on a large scale in an integrated context requires rethinkingtraditional disciplinary workflows and encouraging communication between thedifferent disciplines involved. It is worth noting that the aspectsdiscussed here are mainly viewed from a groundwater perspective, whichreflects the author's background.