Robust rammeverk til estimat av flomhendelser i Norge

Estimates of the size of large floods are needed for constructing new roads and railways, for selecting locations for new housing developments and for constructions located in the watercourse. Since over 95% of Norway's power supply comes from hydro power, potential floods play an important role in the planning of new hydro power plants and dams. To avoid over- or under-investments on dam infrastructure and other infrastructure, it is important to have as precise flood estimates as possible. The aim of the FlomQ project is to improve estimates and the associated uncertainty bounds of rare floods which occur on average every 500 or 1000 years. To this end, we have explored and further developed both precipitation-runoff models and statistical flood frequency approaches. The most promising new methods for our purposes are currently being implemented for use and connected to the flood estimation tools Hydra II and NEVINA. Besides developing new methodology for estimating flood sizes, a vital component of the overall framework is to improve the available data. A new flood database with quality tested data from 530 stations has been established. Further, it has been demonstrated that 3D-models can be used to obtain improved discharge estimates from stage measurements. A physical atmospheric model is being used to improve estimates of extreme precipitation. In addition, the project has organised three open workshops with presentations on the topics of the project, national and international guest speakers and demonstrations of new tools.

Vi har utviklet nye metoder for modellering av vannføringskurver, flomfrekvensanalyse og nedbør-avløps-analyse. Alle de nye metodene viser betydelig bedre prediksjonsevne en de metodene som brukes i dag. Det jobbes per i dag med å implementere disse nye metodene i effektive og brukervennlige verktøy. Det forventes at resultatene fra prosjektet vil bidra til en vesentlig oppgradering i retningslinjer for flomberegninger.

The occurrence of extreme flood events is an important societal issue in Norway where hydro power comprises 95% of the total electricity generation and floods regularly cause damage in urban areas, to infrastructure and cultivated land. Flood protection m easures related to dam safety require techniques for assessing the magnitude of events which have a low probability of occurrence, but which could have catastrophic consequences if structures are under designed for such events. Simultaneously, overly cons ervative estimates of flood magnitudes can contribute to poor use of resources, thus undermining value creation. This project will result in a next-generation flood estimation framework and revised guidelines for flood estimation relevant to dam safety re assessments in Norway. The new products will comprise a complete overhaul of the current practice and will, in particular, include a new and significantly improved methods for uncertainty quantification and better use of the available data.