An integrated, multi-modelling approach for the assessment of water quality: lessons from the Pinios River case in Greece

Major factors influencing water quality along a river are land use practices, seasonal hydro-meteorological conditions, groundwater interactions and wastewater discharges. These complex water quantity and water quality aspects demand integrated solution approaches. The study links hydrologic, hydraulic and water quality models using the OpenMI standard to evaluate water quality in the Pinios River in Greece. OpenMI allows data to be exchanged at run time, between models from different providers, thus facilitating integrated modelling. The Pinios River was selected due to its high intensity of cultivation with water demanding crops. The objectives of the overall project, of which this study forms a part, were to assess water quality during extreme events and identify areas where any further pollution could be critical. A multi-modelling approach was utilized, where two separate integrated models were developed by two different research groups, each combining, using OpenMI, commercial and academic model components, thus creating a form of modelling ensemble. The assumptions and results are compared and critically discussed. The study’s conclusions also address generic integrated modelling issues such as the benefit of bi-directional links and integrated model stability. They also identify challenges in model comparison, within a multi-modelling framework in view of differences in conceptualization, discretisation and solving schemes chosen by different researchers, which become apparent once the barriers for direct comparison are alleviated, with the use of approaches such as OpenMI.