Damage from subsidence becomes more visible the further you go into the passages.
The Directorate for Cultural Heritage has installed a total of 47 monitoring wells in Bryggen, 21 of which contain sensors gathering large amounts of data.
Continuous data collection provides the Directorate with a good picture of developments in Bryggen. The software used by COWI and Cautus allows them to track changes in a host of different parameters, including conductivity, water content, oxygen, redox (chemical energy), pH, pressure, precipitation, temperature and water level.
“The sum of all these figures, and their changes over time, gives us an overall picture of the health of Bryggen in Bergen. We have also collected a lot of historical data from older logs, so we can generate a good overview. The groundwater level has the biggest influence on the health of Bryggen, so of course we monitor that extra closely,” says Soldal.
How the data collected from the sensors is displayed in the software used for monitoring.
A number of measures have been taken to delay subsidence, including raising the water level beneath Bryggen. Infiltration beds with plants placed around Bryggen divert rainwater straight down into the soil. Surface water and water from roof gutters is also collected in a system of gullies and diverted into the ground.
“The key point is that there are enough sensors to enable NIKU and the Directorate for Cultural Heritage to take action just where it is needed the most. The monitoring also allows us to see the effects of new measures,” says Jostein Soldal.
The Directorate for Cultural Heritage says that the monitoring is planned to continue for 4-5 years.
“The groundwater level has risen and the settlement rate has decreased. We now plan to continue the monitoring with measurements and data collection to track the groundwater level and the settlement rate. At the end of this period, we will make a fresh assessment to determine whether the monitoring should be stepped down” says Hanne Merete R. Moldung, senior advisor at the Norwegian Directorate for Cultural Heritage.