Nils Roar Sælthun

• Li, Hong; Gao, Hongkai; Zhou, Yanlai; Storteig, Ina Cecilie; Nie, Linmei & Sælthun, Nils Roar [Show all 7 contributors for this article] (2022). Urban flood modeling of a partially separated and combined drainage system in the Grefsen basin in Oslo, Norway . Journal of Water Management Modelling. ISSN 2292-6062. 30(C480). doi: 10.14796/JWMM.C480.
• Barton, David Nicholas; Venter, Zander; Sælthun, Nils Roar; Furuseth, Ingvild Skumlien & Seifert-Dähnn, Isabel (2021). Brukerfinansiert klimaberedskap? En beregningsmodell for overvannsgebyr i Oslo. Vann. ISSN 0042-2592. 56(4), p. 341–358. Full text in Research Archive Show summary

  A stormwater fee for Oslo? A computational approach to user financed climate readiness. Stormwater fee systems constitute a potential policy instrument for user financed climate readiness in Norwegian cities. Stormwater fees can contribute to operation and future maintenance requirements of stormwater networks and wastewater treatment required with climate change. However, stormwater fees calibrated to a property's stormwater runoff has been criticized for being too complex and expensive to compute. In this paper we show how stormwater fees can be computed for a whole city’s built area adjusted to local property run-off conditions. We demonstrate how a property specific fee can be calculated for all properties in Oslo through the combination of detailed landuse maps, a simple but bespoke hydrological model, estimates of current and expected costs of stormwater networks and treatment due to climate change towards 2040. Calculations are carried out in an online web application in Google Earth Engine. The application makes it possible for the property owner to test the effect of different LID measures on run-off and stormwater fees, providing support for the choice of optimal measures and cost savings. We compare the characteristics of the stormwater fee for Oslo with international experiences from other cities and discuss further technical and practical improvements needed to achieve good stormwater management in a future climate. Our work shows that computation costs are not an important argument against introduction of a user differentiated stormwater fee.

• Li, Hong; Gao, Hongkai; Zhou, Yanlai; Xu, Chong-Yu; Ortega, Rengifo & Sælthun, Nils Roar (2020). Usage of SIMWE model to model urban overland flood: a case study in Oslo. Hydrology Research. ISSN 1998-9563. 51(2), p. 366–380. doi: 10.2166/nh.2020.068. Full text in Research Archive
• Xu, Hongliang; Xu, Chong-Yu; Sælthun, Nils Roar; Xu, Youpeng; Zhou, Bin & Chen, Hua (2015). Entropy theory based multi-criteria resampling of rain gauge networks for hydrological modelling - A case study of humid area in southern China. Journal of Hydrology. ISSN 0022-1694. 525, p. 138–151. doi: 10.1016/j.jhydrol.2015.03.034.
• Xu, Hongliang; Xu, Chong-Yu; Sælthun, Nils Roar; Zhou, Bin & Xu, Youpeng (2015). Evaluation of reanalysis and satellite-based precipitation datasets in driving hydrological models in a humid region of Southern China. Stochastic environmental research and risk assessment (Print). ISSN 1436-3240. 29(8), p. 2003–2020. doi: 10.1007/s00477-014-1007-z.
• Yuan, YB; Zhu, YQ; Zhou, Y; Sælthun, Nils Roar; Cui, W & Huang, JJ (2009). Rough set for quantitative analysis of characteristic information in metallogenic prediction. Kybernetes. ISSN 0368-492X. 38(10), p. 1801–1811. doi: 10.1108/03684920910994321.
• Yuan, Yanbin; Zhou, Youa; Zhu, Yaqiong; Yuan, Xiaohui & Sælthun, Nils Roar (2007). Development of flood routing simulation system of digital Qingjiang based on integrated spatial information technology. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 6795.
• Sælthun, Nils Roar (2007). Impacts on water resources and hydropower production. In Moren-Abat, Marta; Quevauviller, Philippe; Feyen, Luc; Heiskanen, Anna-Stiina; Nooges, Peeter; Solheim, Anne Lyche & Lipiatou, Elisabeth (Ed.), International Workshop Climate Change Impacts on the Water Cycle, Resources and Quality Research-Policy Interface Scientific and policy report. Office for Official Publications of the European Communities. ISSN 92-79-03314-X. p. 93–94.
• Kaste, Øyvind; Wright, Richard; Barkved, Line; Bjerkeng, Birger; Engen-Skaugen, Torill & Magnusson, Jan [Show all 7 contributors for this article] (2006). Linked models to assess the impacts of climate change on nitrogen in a Norwegian river basin and fjord system. Science of the Total Environment. ISSN 0048-9697. 365(1-3), p. 200–222.
• Heal, O.W.; Bayfield, N.; Callaghan, T.V.; Høye, T.T.; Järvinen, A. & Johansson, M. [Show all 12 contributors for this article] (2005). SCANNET: a Scandinavian-North European network of terrestrial field Bases. In Thompson, D.B.A.; Price, M.F. & Galbraith, C.A. (Ed.), Mountains of northern Europe. Conservation, management, people and nature. Scottish Natural Heritage . ISSN 0114973199. p. 359–364.
• Callaghan, T.V.; Johansson, M; Heal, O.W.; Sælthun, Nils Roar; Barkved, Line & Bayfield, N [Show all 27 contributors for this article] (2004). Environmental Changes in the North Atlantic Region: SCANNET as a collaborative approach for documenting, understanding and predicting changes. Ambio. ISSN 0044-7447. 13, p. 39–50.
• Gottschalk, Lars; Krasovskaia, Irina & Sælthun, Nils Roar (2002). Economic risk of flooding: A case study for the Glomma River, Norway. In Bolgov, M.; Gottschalk, Lars; Krasovskaia, Irina & Moore, R.J. (Ed.), Hydrological models for environmental management. NATO Science Series, Kluwer Academic Publishers.. p. 241–263.
• Krasovskaia, Irina; Gottschalk, Lars; Sælthun, Nils Roar & Berg, Hallvard (2001). Perception of Risk of Flooding, Case of 1995 Flood in Norway. Hydrological Sciences Journal. ISSN 0262-6667. 46(6), p. 855–868.
• Gottschalk, Lars; Beldring, Stein; Engeland, Kolbjørn; Motovilov, Yuri; Tallaksen, Lena & Sælthun, Nils Roar [Show all 7 contributors for this article] (2001). Regional/Macro-scale Hydrological modelling:- a Scandinavian experience. Hydrological Sciences Journal. ISSN 0262-6667. 46(6), p. 963–982.

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• Sælthun, Nils Roar (2010). Norway and the University of Oslo, Department of Geosciences.
• Sælthun, Nils Roar (2010). Communicating Climate Change. Show summary

  Communicating Climate Change Nils Roar Sælthun, Department of Geosciences, University of Oslo Abstract The universities have three major tasks serving society: Education, research and communicating research results. Scientists are trained in the two first tasks, but generally not in the third, and their individual capacity, interest and focus on communication and outreach outside scientific publishing varies greatly. Generally, increased pressure to maximize education and scientific publication also reduces the scientists’ possibilities to spend time on communication towards society, however interested they may be in the topic. This is a worrying development, as the modern society is dependent on fast dissemination of knowledge from research to action and innovation. Climate change is one of the most central challenges in modern society. Thousands, not to say millions, of scientists work daily on topics and problems connected to climate change, and their work is synthesised in the IPCC process and reports, which have set the issue high in the awareness of laymen and journalists and high on the political agenda. As such, the IPCC process has been one of the most successful research communication efforts seen in science. Still, when the discussions are running hot and high about the realities in climate change, climate scientists are strangely absent. In a recent study about media coverage of climate change (Eide et al, 2010), the authors find that the scientists constitute only one third of the people engaged in the media coverage of the issue, and that the debate is dominated by politicians, NGOs, journalists and opinion makers outside the climate research society. Most of the active researchers seem to shun the public debate. What are the reasons for this? One part of the explanation is that scientists have their focus on participating in the academic debate through scientific publications and discussions, and not on participating in the public debate. Equally important is probably the fact that communicating climate change to the public is not so much about communicating certain facts, as about uncertainty and risk. This is far more difficult, and also more unrewarding than presenting facts, especially as media and journalists prefers the bombastic statement to presentations of uncertainty. Scientists may fear (often, but not always justified) that their statements about uncertainty will be stripped from the presentations, and that their findings may be presented as more certain than what they can stand for. The opposite position may also hold the scientist back from presenting uncertainty in climate change research: he or she may feel that this could undermine the ”good cause” through presenting the possibility the changes may be less than the average prediction/scenario. When discussing climate change and climate change effects, the consequences of impacts are asymmetrical. The consequences of large changes are dramatically more severe than small changes. In a risk analysis, the large changes will have more weight than the”most likely” changes. This is an issue even more difficult to communicate than uncertainty in itself – how society should be prepared to take action to mitigate impacts that are not necessarily very likely to happen – due to their severity. In reality, the difficulties in communicating uncertainty and risks in climate change may be less than what the researchers in the natural sciences foresee. They do however need training, tools, and examples that can help them in explaining uncertainty without distracting the main message. The universities have a challenge in integrating training in public communication and outreach in their education of researcher, i.e. in the doctoral programmes and research schools.

• Sælthun, Nils Roar (2010). Hydrololgical modelling and forecasting in Norwegian hydropower systems. Show summary

  Hydropower is a dominant energy source in Norway, and provides close to 100% of the electricity production. The Norwegian hydropower companies are also an important part of the Nordic and North Europe electricity systems and markets. The short and medium term availability of water is thus a decisive factor for the price of electricity in the national and regional supply systems. Reliable forecasts of water availability are important for the optimal operation of the systems, and provide the operator with an competetive advantage. As a result, the Norwegian hydropower companies have been a driving force in the development of forcasting systems, and have 30 years of history of use of hydrological models as an integral tool in the operation systems. In addition to the economical advantages of the use of hydrological forecasting systems, they also provides vital information for safe operation in flood situations, and assists in precise release of compensation/ecological flow. The paper reviews the development of hydrological forcasting in hydropower operation in Norway, and describes the present state of the forecasting systems, illustrated with examples from major Norwegian hydropower companies.

• Sælthun, Nils Roar (2007). Impacts/downscaling, abiotic systems.
• Alfredsen, Knut; Finstad, Anders Gravbrøt; Fiske, Peder; Forseth, Torbjørn; Hvidsten, Nils Arne & Jensen, Arne Johan [Show all 12 contributors for this article] (2007). Climate change effects on discharge, hydropower production, water temperature, ice conditions and their impact on Atlantic salmon in the regulated Orkla River in Norway.
• Sælthun, Nils Roar (2007). Klimaendringar og vassdragsforvaltning.
• Sælthun, Nils Roar (2007). Framtidas klima – behov for nye strategiar og tiltak?
• Sælthun, Nils Roar (2006). Status snømodellering.
• Sælthun, Nils Roar (2006). Impacts on water resources and hydropower production. Show summary

  Impacts on water resources and hydropower production Nils Roar Sælthun, University of Oslo, Norway The energy sector is affected by climate change through various mechanisms. The most important are:  Direct effects on the energy production system,  Direct effects on energy consumption,  Indirect effects through mitigation/adaption measures, making greenhouse gas emission neutral production system more competitive than fossile fuel based systems. Hydropower is generally considered to be a greenhouse gas neutral systems, although there are some GHG aspects connected with reservoirs inundating or waterlogging former dry land. Hydropower production systems are influenced by climate change through all mechanisms above, but this presentation will mainly focus on the first effect, i.e. climate change impacts on the resource itself – water availability, and to some extent impacts on system components. These effects are always important for the operation and future investment planning for the individual hydropower company, and the hydropower sector is one of the economic sectors that has shown most interest in climate change research.

• Sælthun, Nils Roar; Barkved, Line Johanne; Kaste, Øyvind & Engen-Skaugen, Torill (2005). The snow that fell last year - was it the last? Snow cover as an indicator of climate change. Show summary

  Transient changes in snow cover depth and duration have been simulated for several small catchments in different altitude zones in south-western Norway, based on dynamically downscaled data from the ECHAM4/OPYC3 Atmosphere-Ocean General Circulation Model run with the IS92a emission scenario. The HBV model has been used for simulation of snow cover, and the runs cover the period up to the middle of this century. The results are less clear-cut than could be expected, especially at low and intermediate altitudes, where “normal” variability to a large extent masks the climate change signal. As snow cover is a very visible climatic indicator, and the Nordic public relates strongly to it, it has the potential to convey strong messages about climatic change. These messages may however in practice be quite confusing. Implications of this and lessons about how to communicate climate change to the public are discussed.

• Sælthun, Nils Roar (2000). Risk analysis project within the Norwegian HYDRA flood research programme.
• Gottschalk, Lars; Beldring, Stein; Engeland, Kolbjørn; Tallaksen, Lena; Sælthun, Nils Roar & Motovilov, Yuri (2000). Macro-scale hydrological modelling - A Scandinavian experience.
• Engeland, Kolbjørn; Gottschalk, Lars; Sælthun, Nils Roar & Tallaksen, Lena (2000). Distributed modelling using global parameter sets. Show summary

  The Norwegian project 'New Generation of Hydrological Models' is aimed at developing meth-ods and algorithms for spatially distributed rainfall/runoff models, including methods for pre-cipitation estimation and new updating techniques. the application of the ECOMAG model in the NOPEX project is the starting point for the model development at the Department of Geophysics. In our context, distributed hydrological modelling implies the repeated use of a model within a re-gion using a global set of parameters. Some important points in a model development strategy are: 1) Define an appropriate scale for the model units. 2) Description of the physical processes at that scale. 3) Estimation of global parameters. 4) brief overview of activities connected to each of these points is given below, with special em-phasis on the estimation of global parameters.

• Sælthun, Nils Roar; Barton, David Nicholas & Venter, Zander Samuel (2021). REO: estimering av overflateavrenning fra urbane felt. Beregningsgrunnlag for et arealdifferensiert overvannsgebyr (revidert utgave). Norsk institutt for naturforskning (NINA). ISSN 978-82-426-4723-8. Show summary

  NOU 2015:16 Overvann i byer og tettsteder foreslår overvannsgebyr som et av flere måter å finansiere overvannstiltak. Det har manglet en hydrologisk beregningsmetode som tar for seg hele arealet i en byggesone, som kan differensiere relativt overvannsansvar på eiendomsnivå, samtidig som den ikke krever kalibrering med lange hydrologiske tidsserier. Rapporten dokumenterer en hydrologisk modell for beregning av overvannsavrenning på årsbasis på eiendomsnivå, som beregningsgrunnlag for variabel del av kommunale overvannsgebyr. Modellen Rasjonale formel for Estimering av Overvannsproduksjon (REO) - skal være enkel nok til at den kan implementeres i en online GIS-kartløsning basert på lett tilgjengelige arealdekkekart, og detaljert nok til å identifisere det relative ansvaret på eiendomsnivå for ‘overvannsproduksjon’. R i REO indikerer at modellen er bygd rundt den rasjonale formel. Den rasjonale formel eller rasjonale metode er et av de mest brukte verktøy i hydrologisk dimensjonering, med enkel parametrisering som gjør det mulig å implementere for hele byggesonen. Arealbrukstypene som er modellert, er kompatible med tiltak i Oslo kommunes metode for Blågrønn faktor. Modellen er implementert i et Excel-verktøy for estimering av overflateavrenning fra urbane felt, både flomtopp og totalav-renning. Modellen danner videre grunnlaget for beregning av overvannsgebyr i en online applikasjon utarbeidet av Zander Venter (NINA): https://nina.earthengine.app/view/new-waterways. Overvannsgebyr-applikasjonen er et verktøy for utforsking av ulike scenarier for overvannsgebyr med Oslo som eksempel.

• Sælthun, Nils Roar & Lindholm, Oddvar (2000). Forurensningsproblemer i og fra tettsteder i forbindelse med flom. Norges Vassdrags- og Energidirektorat. ISSN 82-410-0428-1.
• Sælthun, Nils Roar; Berg, Hallvard; Voksö, A.; Eggestad, Hans Olav; Gottschalk, Lars & Karasovskaia, I. [Show all 9 contributors for this article] (2000). Økonomisk risikoanalyse for flommer. NVE.
• Krasovskaia, Irina; Gottschalk, Lars; Sælthun, Nils Roar & Berg, Hallvard (2000). Kampen mot vannet - risikovurderinger og handlingsvalg blant lokale beslutningstakere og publikum. Norges vassdrags- og energidirektorat.
• Sælthun, Nils Roar (1999). Flommer, flomsikring og miljø - konflikt eller konsensus. Norges vassdrags- og energidirektorat. ISSN 82-410-0427-3.
• Sælthun, Nils Roar & Lindholm, Oddvar (1999). Forurensningsproblemer i og fra tettsteder i forbindelse med flom. Norges vassdrags- og energidirektorat. ISSN 82-410-0428-1.

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