Analysis of intensively used catchments based on integrated modelling

Abstract

► An integrated immission based catchment model for peri-urban catchments is developed. ► Models for urban and rural parts and the water body are coupled via OpenMI. ► Water quantity and quality are modeled spatially and temporally detailed for urban and rural areas and the receiving water body. ► Results show that neglecting impacts from one area leads to significant errors. ► The developed model is freely available at http://bluemodel.org/. A model system that overcomes the separation of rural and urban areas for an integrated immission based modelling of catchments with complex land use is presented. To account for both the sewer system dynamic processes and the dynamics of single events in the runoff processes from rural areas, the model operates on a high temporal resolution and in continuous mode. The basic system structure and the rural areas are represented by means of a semi-distributed rainfall-runoff and pollution load model that allows for a user-specified spatial resolution. For each urbanized area within the catchment an urban hydrological pollution load model is used. This allows for a detailed assessment of the urban drainage structure even for multiple settlements within one catchment. Pollutant transport, mixing, and transformation processes within the receiving water body are modelled to account for accumulating and long-term effects. The model concept was applied to a real world case study. It was found that the consideration of all impacts is essential for an immission based approach. It can be concluded that a realistic description of the water body status can only be achieved by means of a detailed representation of both flow and mass transport processes in urban and rural parts of the catchment as well as the receiving water body in a high temporal and spatial resolution.