Glacier outlines Nordland 1900

ArcGIS geodatabase containing Glacier Area Outlines (GAO) of all glaciers (n = 1587) in the northern Norwegian county of Nordland, including a small number of glaciers in the adjacent counties, in ca. 1900 (1882-1916). Glacier outlines were digitised from georectified historical gradteigskart maps, published by Norges geografiske oppmåling (NGO; Norwegian Geographical Survey; now: Kartverket – Norwegian Mapping Authority). These maps are based on field surveys carried out between 1882 and 1916. The data set and the uncertainties associated with it are described in detail in Weber et al. (2020; Journal of Glaciology)

Effektiv kommunikasjon av naturfarevarsel fra NVE : hvordan kan NVE best formidle naturfarevarsler?

Prosjektet «Effektiv kommunikasjon av naturfarevarsel» ble gjennomført i regi av NVE i periode 2017-2018. Hovedmålet var å undersøke om naturfarevarslene blir forstått og utløser endret adferd hos brukerne av tre av våre varslingstjenester. Rapporten oppsummerer de viktigste funnene fra tre undersøkelser gjennomført i form av telefonintervju og nettundersøkelse. Vi har også samlet og gjennomgått internasjonale artikler om analyse av varselteksten, brukeradferd og risikokommunikasjon. 12 beredskapsansvarlige fra 12 kommuner spredt utover Vest, NordVest, Nord-Norge og Østlandet ble intervjuet på telefon og ble bedt å analysere tekstene av ulike flom-, jordskred- og snøskredvarsler. En nettundersøkelse ble brukt for å analysere snøskredvarsel, den involverte 200 snøskredeksperter og 485 brukere av snøskredvarse

Naturfareforum : probabilitet og stabilitet

Naturfareforum har gjennomført et seminar for å belyse muligheter og begrensninger knyttet til bruk av probabilistisk teori og metoder i geotekniske stabilitetsvurderinger/-beregninger. NGI har gjennomført arbeidet med grunnlagsdokumentasjonen, og inviterte deltakere har levert bidrag på bakgrunn av dette. Rapporten omfatter grunnlagsdokumentasjon, presentasjoner og refleksjoner i etterkant av seminaret

A parameter parsimonious approach for catchment scale urban hydrology – Which processes are important?

Increased urbanization and increased observed precipitation intensity and -frequency due to climate change call for urban hydrological models capable of describing urban flow dynamics in data-scarce areas. A parameter parsimonious rainfall-runoff model, DDDUrban, forced by precipitation and temperature in which most model parameters are estimated from a detailed digital elevation model using GIS or taken from the literature is presented. Snowmelt and evapotranspiration are calculated using an energy balance approach, with proxy models for the energy balance elements driven by temperature and precipitation. The model focusses on subsurface and surface flow processes using an analysis of travel time distributions which indicates that the shape of the urban hydrograph is largely independent of the comparatively very rapid process of water transport in conduits. The model uses an estimate of the distribution of subsurface velocities as a function of saturation. The study shows that the calibrated mean of this distribution agrees with the saturated hydraulic conductivity estimated from infiltration measurements. The model has been calibrated and validated on observed runoff data at a 10 min temporal resolution for two Norwegian catchments in Oslo and Trondheim with acceptable validation results measured by the Kling-Gupta Efficiency criterion (KGE = 0.56–0.69). Simulations show that precipitation infiltrated on permeable areas contributes, on average, to the total flow at a fraction corresponding to the areal fraction of permeable areas. In addition, simulations show that for saturated conditions, a significant part (~30–60%) of the flood peak is derived from saturation excess overland flow. Simulation of snowmelt indicates that a more detailed model for the spatial distribution of snow accounting for snow removal, is needed. The catchment-scale effects of Low Impact Developments in the form of 10 m2 raingardens are simulated. In a residential area with 500 houses, 60 raingardens can reduce the flood peaks about 10%. A higher number of raingardens further reduce the flood peaks, but raingardens of too low capacity may increase secondary flood peaks for episodes of multiple heavy precipitation events

erfaringer fra utforming og drift -2019

For å øke kunnskapen om drift og erfaringer med coanda-inntak gjennomførte NVE en spørreundersøkelse om dette i 2019. Undersøkelsen ble sendt til samtlige konsesjonsgitte småkraftverk med coanda-inntak som er satt i drift. Multiconsult har sammenstilt svarene fra undersøkelsen. 30 kraftverk har deltatt, og gjennomsnittlig driftserfaring er litt over to år. De fleste kraftverkseiere er tilfredse med coanda-løsningen, til tross for utfordringer knyttet til blant annet isdannelse og algevekst. Rapporten sammenstiller også erfaringer fra drift av coanda-inntak i Skottland og Canad

Ecological correlates of riverine diatom and macroinvertebrate alpha and beta diversity across Arctic Fennoscandia

Arctic freshwaters support biota adapted to the harsh conditions at these latitudes, but the climate is changing rapidly and so are the underlying environmental filters. Currently, we have limited understanding of broad‐scale patterns of Arctic riverine biodiversity and the correlates of α‐ and β‐diversity. Using information from a database set up within the scope of the Arctic Council's Conservation of Arctic Flora and Fauna Circumpolar Biodiversity Monitoring Plan, we analysed patterns and correlates of α‐ and β‐diversity in benthic diatom and macroinvertebrate communities across northern Norway, Sweden, and Finland. We analysed variation in total β‐diversity and its replacement and richness difference components in relation to location of the river reach and its drainage basin (Baltic Sea in the south, the Barents Sea in the east and the north, and the Norwegian Sea in the west), in addition to climate and environmental variables. In both macroinvertebrates and diatoms, the replacement and richness difference components showed wide variation. For macroinvertebrates, the richness difference component was the more important, whereas for diatoms, the replacement component was the more important in contributing to variation in β‐diversity. There was no significant difference in β‐diversity between the three main drainage basins, but species composition differed among the drainage basins. Based on the richness difference component of β‐diversity, climate variables were most strongly associated with community variation in macroinvertebrates. In diatoms, both environmental and climate variables were strongly correlated with community compositional variation. In both groups, there were also significant differences in α‐diversity among the three main drainage basins, and several taxa were significant indicators of one of these drainage basins. Alpha diversity was greater in areas with a continental climate, while the oceanic areas in the west harboured greatly reduced flora and fauna. The correlates of biodiversity were relatively similar in macroinvertebrates and diatoms. Climate variables, in particular temperature, were the most strongly associated with biodiversity patterns in the Arctic rivers of Fennoscandia. Sedimentary geology may be associated with increased productivity and, to a lesser extent, with sensitivity to acidification. There was considerable variation in community composition across Arctic Fennoscandia, indicating the necessity of protecting several stream reaches or even whole catchments within each region to conserve total riverine biodiversity. Furthermore, it is likely that the predicted changes in temperature in Arctic areas will influence riverine diversity patterns across Fennoscandia.Norwegian Water Resources & Energy Directorate Norwegian Institute for Water Research Ministry of Foreign Affairs, Finland Norwegian Environmental Agenc

DDDUrban, ny urbanhydrologisk modell, – resultater fra SURF-prosjektet

Økt urbanisering og klimaforandringer etterspør urbanhydrologiske modeller som kan beskrive urban avrenning også for områder med lite målinger. Vi presenterer en parameter gjerrig nedbør-avløps modell, DDDUrban som beskriver vannbalansen i et urbant nedbørsfelt og hvor de fleste modellparametere er bestemt fra en terrenganalyse ved hjelp av GIS. DDDUrban er kalibrert og validert for to nedbørsfelt i Oslo og Trondheim med vannføringsdata på 10 min oppløsning med tilfredsstillende valideringsresultater (KGE= 0.56-0.69). Modellsimuleringer viser at i) kalibrerte grunnvannshastigheter stemmer overens med målt mettet hydraulisk konduktivitet, ii) nedbør som faller over permeable områder bidrar til totalavrenningen tilsvarende fraksjonen av permeable områder og iii) ved mettet tilstand vil en signifikant del (~30-60 %) av flomtoppen være overflate avrenning fra mettede permeable områder

Forest as protection against natural hazard : classification of knowledge and adaption to the classification system of Nature in Norway (NiN)

Rapporten presenterer forslag til enhetlig beskrivelse av de egenskapene ved skog som har vesentlig betydning for skogens funksjon som vern mot naturfare

Geographic variation and temporal trends in ice phenology in Norwegian lakes over a century

Observations from 1890 to 2020 of ice phenology for 101 Norwegian lakes were used to detect variation in ice phenology. The average date of ice break-up occurred later in spring with increasing altitude, latitude and longitude. The average date of freeze-up and the length of the ice-free period decreased with altitude and longitude. Lakes were completely frozen later recently later in autumn. A significant trend for earlier break-up, later freeze-up and completely frozen lakes after 1991

Naturfareforum : årsrapport 2019

I denne rapporten er aktivitetene og ressursbruken i Naturfareforum 2019 oppsummer