Mapping of climate-related natural hazards

The municipalities in Øvre Romerike have received grants from the Norwegian Environment Agency's program for climate adaptation (in Norwegian only). The purpose of the subsidy scheme is to promote work on climate adaptation by contributing to increased knowledge about how climate change affects municipalities, and what measures must be implemented to meet climate change. NGI will assist the municipalities in Øvre Romerike in this work.

Areas prone to landslides and floods

The municipalities of Gjerdrum, Ullensaker, Nes, Hurdal, Eidsvoll and Nannestad want to map and identify areas that will be particularly exposed to natural hazards in the future, based on forecasts of a "wilder and wetter" climate towards the end of the century. Increased precipitation will lead to more saturated soil, increased water flow in streams and rivers, as well as an increased risk of erosion, which in turn can lead to a greater risk of various types of floods and landslides.

The mapping will contribute as a professional basis in the municipalities' continuous overall risk and vulnerability analysis, for the category natural events. NGI is preparing a GIS methodology to map natural hazards in the years 2070-2100 based on the expected increase in precipitation. The natural hazards that are expected to increase in frequency and intensity due to increased precipitation are landslides, quick clay landslides (with a focus on erosion potential), floods and surface water.

Aid in infrastructure upgrading

Maps with the municipalities' critical infrastructure will be combined with maps for natural hazards 2070-2100, and thus provide important information about areas that are particularly vulnerable in the future climate. Relevant infrastructure can be roads, railways, pipelines (water, sewerage and electricity), cables (telecommunications and electricity), masts, transmitters and the like. The level of detail and what the project will include in terms of infrastructure is agreed in close collaboration with the municipalities.

It is a goal that the new maps should appear as intuitive as possible, so that they can be used by many disciplines within the municipalities. The maps can, among other things, be used to make it visible to suppliers of electricity and fibre optics to where it is most appropriate to lay cables. When renewing of the water and sewage network (target of 2% annually), the maps can be used to assess future difficulties, as well as changing routes for the most exposed sections where possible. The results must also be able to be used in the municipalities' spatial planning.

Part of the background for the need for such a survey is the desire to avoid situations such as Nittedal municipality experienced in the autumn of 2019, where the main water supply, sewage-line, and fiber and power cables were all in the same trench - and a landslide destroyed everything.