Impact of changing weather patterns on bathing water and seafood quality from the Inner Oslofjord.
It is an important goal to provide good hygienic bathing water quality at designated beaches in the Inner Oslofjord during the bathing season, and several measures have been implemented in recent years in order to reduce the sewage loads to the fjord. However, external pressures, including increased population in urban areas and more heavy precipitation in recent summers have to some extent counteracted the benefits derived from these measures. More precipitation affects the local loads of faecal microorganisms to the fjord, e.g. due to discharges from combined sewer overflows (CSOs) and urban and rural surface runoffs.
Another challenge for the city of Oslo is the redevelopment of the inner harbour area into residential and recreational areas. The water quality in these areas is historically poor, but politicians and the public expect the relevant authorities to ensure good quality of bathing water within a few years. New measures for reducing the sewage loads to the fjord are therefore planned or on-going, and these require large investment costs
The main objective of the project is to provide new knowledge and tools for quantifying the pollution potential from different discharge points to Inner Oslofjord – for prioritizing measures for obtaining good water quality in the fjord under future climatic conditions.
- Quantify the input of faecal microorganisms and selected chemical contaminants to the Inner Oslofjord from different sources under different weather conditions
- Collect information and develop process models that describe the fate of faecal microorganisms in the fjord
- Provide a 3D-model for the Inner Oslofjord for simulation of the transport of faecal microorganisms in the fjord
- Use the model for scenario based analysis of the effect of weather conditions, population increase and measures on the hygienic water quality at selected beaches (current and future conditions)
- Obtain more knowledge about the presence of specific pathogens (parasitic protozoa, viruses and bacteria) at selected beaches after different weather conditions. Test/develop rapid methods for monitoring bathing water quality, including methods for real-time warnings after short-term pollution
The project is funded by Regionale Forskningsfond Hovedstaden.
The figure shows simulated concentrations of E. coli at bathing places in Oslo during heavy rainfall/large discharges from combined sewer overflows (CSOs). Only discharges via the largest rivers and CSOs direct to the fjord at Lysaker and Bekkelaget are included. Transport modelling will be an important task in the project to theoretically investigate the effect of different discharges on the different bathing places, how long time after heavy rainfall the bathing water quality is unacceptable at affected beaches, and for investigating the effect of measures.