Towards a distributed physically based model description of the urban aquatic environment

MIKE SHE, a distributed physically based 3D modelling package, has recently been applied in the urban modelling area through a research project in Sweden, funded by the Swedish Water and Wastewater Works Association. The overall goal was to test if it is possible to describe the surrounding geohydrological processes and their interaction with the sewer network, similar to the way dynamic pipe flow modelling can give a detailed description of the hydraulics. The project was carried out in Vittskövle, a village outside the City of Kristianstad, Sweden. The village has extreme inflows to its treatment plant due to large amounts of groundwater infiltration into the sewer network. A MIKE SHE model was built and verified successfully for the catchment. Simulations were carried out in order to evaluate the effects from historical measures and alternative future alleviation schemes. The results indicate among others, that the construction of a new alternative drainage scheme would make it possible to reduce the inflow to the plant by as much as 75% without risk of increased groundwater levels. The application of MIKE SHE in Vittskövle shows expressively the possibilities and applicability of the model in urban areas. Compared with more simple conceptual models, MIKE SHE provides the possibility to analyse the effects from future changes in the geohydrological system.