Tone Muthanna (Norway) 1; Erle Kristvik (Norway) 1; Sveinung Sægrov (Norway) 1; Magnar Sekse (Norway) 2
1 - Norwegian University of Science and Technology (NTNU); 2 - Bergen Municipality
Climate change will impact the urban water systems’ service level.The key issues in Bergen include sea level rise, flooding, variations in ground water level, and maintenance of sewer systems. The impacted sectors are tourism and waste water systems. In order to make plans that will add resilience to performance of the urban water system it is necessary to have both the long and medium short term in mind. Usually climate change studies run for a 50 or 100 years period, which can make it difficult for decision-makers to prioritize the urgency of the actions they need to take.
The BINGO project attempted to overcome this by analysing the impacts of climate change on the water cycle for the short range (time horizon 2025), including those of extreme events, as well as for longer term series. In the Bergen case we have focused on two specific areas:
- the drinking water supply;
- the risk of combined sewer overflows.
This paper will focus on the second part, where three specific tasks have been performed:
- Sewer systems modelling for impact of CSO today and in the near future;
- The possibility to use urban streets as floodways to avoid CSOs;
- Using rain gardens and nature based solutions to mitigate downstream CSOs.
The results showcase the vulnerability to CSOs in the Damsgaard research site, and the mitigation needs. The flood way study showed potential, but also important aspects that need further evaluation. The use of nature based solutions in connection with the combined sewer can provide contributions to reduce the CSOs.