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  • 251. Brandimarte, L
    et al.
    Di Baldassarre, Giuliano
    UNESCO-IHE Institute for Water Education, Westvest 7, P.O. Box 3015, 2601, DA, Delft, The Netherlands .
    Bruni, G
    D’Odorico, P
    Montanari, A
    Relation Between the North-Atlantic Oscillation and Hydroclimatic Conditions in Mediterranean Areas2011Inngår i: Water Resources Management, Vol. 25, nr 5, s. 1269-1279Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mediterranean basins are known for their susceptibility to water stress conditions resulting from a reduction in winter-season precipitation. This region is also prone to the effects of the North Atlantic Oscillation (NAO), a large-scale climatic pattern associated with a displacement of air mass between the arctic and the subtropical Atlantic. Even though previous studies have demonstrated the impact of the NAO on winter climate conditions in Europe and Northern Africa, it is still unclear to what extent the NAO is related to hydroclimatic patterns in Mediterranean areas and whether it can explain its recent drought history. To this end, this study investigates the interdependence between the NAO and winter precipitation, river flow and temperature in two Mediterranean regions: Southern Italy and Nile Delta (Egypt). The outcomes show the presence of significant connections between the NAO, winter rainfall and river discharge.

  • 252. Brandimarte, Luigia
    et al.
    Di Baldassarre, Giuliano
    UNESCO-IHE, Institute for Water Education, Delft, The Netherlands .
    Uncertainty in design flood profiles derived by hydraulic modelling2012Inngår i: Hydrology Research, ISSN 1998-9563, Vol. 43, nr 6, s. 753-761Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The scientific literature has widely shown that hydraulic modelling is affected by many sources of uncertainty (e.g. model structure, input data, model parameters). However, when hydraulic models are used for engineering purposes (e.g. flood defense design), there is still a tendency to make a deterministic use of them. More specifically, the prediction of flood design profiles is often based on the outcomes of a calibrated hydraulic model. Despite the good results in model calibration, this prediction is affected by significant uncertainty, which is commonly considered by adding a freeboard to the simulated flood profile. A more accurate approach would require an explicit analysis of the sources of uncertainty affecting hydraulic modelling and design flood estimation. This paper proposes an alternative approach, which is based on the use of uncertain flood profiles, where the most significant sources of uncertainty are explicitly analyzed. An application to the Po river reach between Cremona and Borgoforte (Italy) is used to illustrate the proposed framework and compare it to the traditional approach. This paper shows that the deterministic approach underestimates the design flood profile and questions whether the freeboard, often arbitrarily defined, might lead to a false perception of additional safety levels.

  • 253. Brandimarte, Luigia
    et al.
    Paron, Paolo
    Di Baldassarre, Giuliano
    UNESCO IHE, Inst Water Educ, Westvest 7, NL-2601 DA Delft, Netherlands.
    Bridge pier scour: A review of processes, measurements and estimates2012Inngår i: Environmental Engineering and Management Journal, ISSN 1582-9596, E-ISSN 1843-3707, Vol. 11, nr 5, s. 975-989Artikkel i tidsskrift (Fagfellevurdert)
  • 254.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    Areella snöstudier1986Rapport (Annet vitenskapelig)
    Abstract [sv]

    Den areella variationen hos ett snötäcke påverkas av mångafaktorer. De meteorologiska förhållandena - främst temperaturoch fuktighet - när snön faller, styr snöns ursprungligadensitet och djup. Vind under och efter snötillfället förflyttarsnön. Den ansamlas i svackor och längs hinder, texlängs skogsgränser, och eroderas på utsatta platser, såsomryggar. Snöförluster orsakade av smältning och avdunstningpåverkar även snöackumulationen.

  • 255.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    Bestämning av optimalt klimatstationsnät för hydrologiska prognoser1987Rapport (Annet vitenskapelig)
    Abstract [sv]

    Det är lätt att avfärda dåliga prognosresultat med att klimatstationsnätet är för glest för att man skall kunna bestämma vinternederbörden korrekt. För att testa antalet behövliga temperatur- och nederbördsstationer för olika typer av områden har vi därför prövat att ändra antalet temperatur- resp. nederbördsstationer och studerat hur det påverkar simuleringarnas precision.Studien har finansierats av Vattenregleringsföretagens samarbetsorgan(VASO).

  • 256.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    GENERATION, TRANSPORT AND DEPOSITION OF SUSPENDED AND DISSOLVED MATERIAL - EXAMPLES FROM SWEDISH RIVERS1990Inngår i: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 72, nr 3-4, s. 273-283Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Soil erosion, sediment transport and deposition in river systems in Sweden are discussed. The database consists of observations from a research project and from the Swedish network for the measurement of sediment transport. Examples are given from measurements in small plots, and from river basins of different sizes and characteristics. Effects of hydrological regime, of deposition in lakes, and of geology and human impact are illustrated. It was found that observations of erosion losses in index plots cannot easily be extrapolated to large areas, and that trends of transport most likely reflect trends in runoff.

  • 257.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    Human impacts and weather-dependent effects on water balance and water quality in some Swedish river basins1990Rapport (Annet vitenskapelig)
    Abstract [en]

    The weather has a great effect on the water balance and, indirectly, affects water quality of river systems. At the same tirne, man-made changes in the Iandscape and other human activities have a great impact. To be able to distinguish the human irnpacts from the effects of natura! weather fluctuations we need observations and measurements but also analysis tools.

    In this thesis the PULSE and HBV hydrological models have been used as the analysis tools. Examples are given from forest management, in particular clearcuning, drainage and biomass increase, and from mining and agricultural activities. The models include conceptual descriptions of the most significant hydrological processes and are capable of coping with. weather-dependent fluctuations. Observed air temperature, precipitation and an estimate of the potential evapotranspiration are input data to the models.

    Simple hydrochemical and nitrogen leaching subroutines have been Iinked to the PULSE water balance model.These subroutines have been used to quantify weather-dependent and human effects on pH downstream from a mine tailings deposit and on nitrogen Ieaching from different non-point sources, especially from arable land.

    The applications illustrate the advantage of this type of model for analysis of man-made irnpacts and short-term climatological fluctuations. As the models are restricted to stationary conditions they cannot be used for forecasting of long-term changes due to changes in atmospheric deposition, land use or climate, unless the local effects of these changes are known. Other methods of analysing effects of man-made changes have also been tested, such as conventional comparative investigations, regression analysis and trend analysis. The use of these methods is exemplified by an analysis of human effects on erosion and sediment transport. It was found to be much more difficult to quantify effects with these sirnpler methods

  • 258.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    Sedimenttransport i svenska vattendrag exempel från 1967-19941996Rapport (Annet vitenskapelig)
    Abstract [sv]

    "Sedimenttransport i svenska vattendrag exempel från 1967-1994" är framtagen inom Analysenheten på Affärsområde Samhälle vid SMHI.

    Många års mätning inom sedimenttransportnätet ligger till grunden för denna bearbetning.

    Månads- och årsvärden på halter och transporter finns bearbetade och lagrade för alla stationer. Dessa kan beställas från SMHI. I denna rapport redovisas delar av detta material.

  • 259.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    SIMULATION OF RUNOFF AND NITRATE TRANSPORT FROM MIXED BASINS IN SWEDEN1990Inngår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 21, nr 1, s. 13-34Artikkel i tidsskrift (Fagfellevurdert)
  • 260.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    Skogens inverkan på vattenbalansen1992Rapport (Annet vitenskapelig)
    Abstract [sv]

    Virkesmängden i Sveriges skogar har ökat under 1900-talet och i första hand beror det på ökad skogsproduktion. I södra Sverige har även skogsrnarksarealen ökat något. Eftersom träd tar upp vatten från marken, har det diskuterats om detta innebär att avdunstningen ökat och i sin tur avrinningen minskat. Frågan har analyserats dels genom beräkning av differensen mellan nederbörd (omräknad till areell och höjdkorrigerad nederbörd) och avrinning, dvs ett relativt mått på evapotranspirationen, för ett antal avrinningsområden i Sverige, och dels genom modellsimulering med HBVmodellen från 1930-talet och framåt.

    Differensberäkningen utifrån den uppmätta nederbörden och avrinningen visar att våta år medför inte bara hög avrinning utan även ofta något högre evapotranspiration än torra år. Man kan inte se några tydliga förändringar i evapotranspirationen i någon av de undersökta områdena mer än mindre upp- och nergångar, som troligen mest beror på klimatets fluktuationer.

    Indata till modellen är nederbörd och lufttemperatur. Modellen tar hand om de väderberoende fluktuationerna och gör det är lättare att skilja klimatförändringar från effekten av ändrad markanvändning. Inte heller den analysen visar några klara trender i evapotranspirationen och avrinningen. Eventuella förändringar försvinner i det brus som uppstår av ofullständiga indata (ett glest nederbördsnät på grund av kravet på homogena långa serier) och på de förenklingar av naturen som ändå sker i modellen. Studien tyder alltså på att det inte skett några tydligt påvisbara förändringar av evapotranspirationen och avrinningen på grund av ökad skogstillväxt.

  • 261.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    Snömätning med georadar och snötaxeringar i övre Luleälven1991Rapport (Annet vitenskapelig)
    Abstract [sv]

    Snömätning med flygburen georadarutrustning (i helikopter) har utförts längs fasta linjer i övre Luleälvens tillrinningsområde i april under åren 1986 till 1990. I prognosområdena Suorva, Parki och Tjaktjajaure, som domineras av kalfjäll och där nederbördsstationsnätet är mycket glest, visar de fem årens mätningar, att en uppdatering av HBV-modellens snömagasin utifrån georadarmätningarna kan förbättra prognosutfallet. För skogsområdena Porjus och Letsi, som har ett mer representativt nederbördsstationsnät och bättre prognosutfall, är det svårare att förbättra prognoserna.

  • 262.
    Brandt, Maja
    et al.
    SMHI, Samhälle och säkerhet.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    INTEGRATION OF FIELD DATA INTO OPERATIONAL SNOWMELT-RUNOFF MODELS1994Inngår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 25, nr 1-2, s. 101-112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conceptual runoff models have become standard tools for operational hydrological forecasting in Scandinavia. These models are normally based on observations from the national climatological networks, but in mountainous areas the stations are few and sometimes not representative. Due to the great economic importance of good hydrological forecasts for the hydro-power industry attempts have been made to improve the model simulations by support from field observations of the snowpack. The snowpack has been mapped by several methods; airborne gamma-spectrometry, airborne georadars, satellites and by conventional snow courses. The studies cover more than ten years of work in Sweden. The conclusion is that field observations of the snow cover have a potential for improvement of the forecasts of inflow to the reservoirs in the mountainous part of the country, where the climatological data coverages is poor. This is pronounced during years with unusual snow distribution. The potential for model improvement is smaller in the climatologically more homogeneous forested lowlands, where the climatological network is denser. The costs of introduction of airborne observations into the modelling procedure are high and can only be justified in areas of great hydropower potential.

  • 263.
    Brandt, Maja
    et al.
    SMHI, Samhälle och säkerhet.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    Gardelin, Marie
    SMHI, Affärsverksamhet.
    MODELING THE EFFECTS OF CLEARCUTTING ON RUNOFF - EXAMPLES FROM CENTRAL SWEDEN1988Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 17, nr 5, s. 307-313Artikkel i tidsskrift (Fagfellevurdert)
  • 264.
    Brandt, Maja
    et al.
    SMHI, Samhälle och säkerhet.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    Gardelin, Marie
    SMHI, Affärsverksamhet.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Modellberäkning av extrem effektiv nederbörd1987Rapport (Annet vitenskapelig)
    Abstract [sv]

    Följande analys av vattenbalansen vid extrema situationer är ett led i Flödeskommittens arbete med att ta fram nya riktlinjer för dimensioneringsberäkningar för dammar och utskov, som inleddes våren 1985 (Ehlin, 1986). Frågan fick förnyad aktualitet i samband med höstflöden 1985 och 1986, som orsakade översvämningar och ett antal mindre dammras.De viktigaste faktorerna för beräkning av dimensionerande flöden är arealnederbörd, snösmältning, markfuktighet samt flödessituationen före flödet. En analys av extrem nederbörd har utförts (Vedin och Eriksson, 1986). För beräkning av effekten av den extrema nederbörden på flödet behöver även kombinationer av eventuell snösmältning och markfuktighetsunderskott i marken vara kända. Hur stor snösmältning kan tänkas ske i ett avrinningsområde? Kan vi räkna med att marken är helt mättad? Ett sätt att analysera detta är att med HBV-modellen ta fram extrema arealnederbörds- och snösmältningsvärden samt lägsta  markfuktighetsunderskott. I denna rapport redovisas en analys, som bygger på HBV-modellberäkningar i tjugofem avrinningsområden. Sammanlagt täcker områdena 79 000 km2 av Sveriges totala yta på449 000 km2. Den sammantagna tidsperioden för beräkningarna är475 år.

  • 265.
    Brandt, Maja
    et al.
    SMHI, Samhälle och säkerhet.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    Sandén, Per
    SMHI, Forskningsavdelningen, Hydrologi.
    ENVIRONMENTAL IMPACTS OF AN OLD MINE TAILINGS DEPOSIT - MODELING OF WATER-BALANCE, ALKALINITY AND PH1987Inngår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 18, nr 4-5, s. 291-300Artikkel i tidsskrift (Fagfellevurdert)
  • 266.
    Brandt, Maja
    et al.
    SMHI, Samhälle och säkerhet.
    Ehlert, Kurt
    SMHI, Samhälle och säkerhet.
    Avrinningen från Sverige till omgivande hav1996Rapport (Annet vitenskapelig)
    Abstract [sv]

    Avrinningen från Sverige till omgivande hav har beräknats från 1931 och framåt dels utifrån direkta vattenföringsbestämningar i större vattendrag och dels genom uppskattningar av vattenflödet för kustområden och små avrinningsområden med hjälp av referensstationer. Uppmätta vattenföringsuppgifter finns från 86% av landarealen. Beräkningarna är lagrade som månads- och årsvärden för alla huvudvattendrag, som mynnar i havet, samt för alla kustområden mellan dessa. Beräkningar finns för 265 områden.Grundvattenflöde som ej förs ut med vattendragen har uppskattats till 0,4 promille av totala avrinningen från Sverige.I rapporten presenteras i tabeller 30-årsmedelvärden och månadsmedelvärden för de större floder vid mynningen och för större kustområden inkluderat mindre vattendrag för perioden 1931-1990. Dessutom redovisas långtidsförändringar, trender och säsongsvariationer samt tillrinningen till havet längs olika kuststräckor.

  • 267.
    Brandt, Maja
    et al.
    SMHI, Samhälle och säkerhet.
    Grahn, Gun
    SMHI.
    Avdunstning och avrinningskoefficient i Sverige 1961-1990: Beräkningar med HBV-modellen1998Rapport (Annet vitenskapelig)
    Abstract [sv]

    Världsmeteorologiska organisationen (WMO) har fastställt att statistiska parametrar, som används för klimatbeskrivningar, skall beräknas för sk normalperioder orn 30 år, såsom 1931-1960, 1961-1990. I Sveriges Nationalatlas (SNA 1995) redovisas ett stort antal kartor för olika parametrar (nederbörd, avrinning, avdunstning, temperatur, snödjup osv) för perioden 1961-1990. Avrinningskartan i SNA togs fram med hjälp av HBV-modellen.Modellen beskriver vattnets kretslopp från nederbörd, snöackumulation till snösmältning, avdunstning, buffring i marken, grundvattenbildning och avrinning på daglig basis, vilket gör det möjligt att plocka ut mer resultat för fler parametrar än bara avrinningen både i rummet och tiden.

    I denna rapport har avdunstningen och avrinningskoefficienter i Sverige närmare studerats utifrån de körningar som gjorts för perioden 1961-1990. Diagrammen och kartorna i rapporten är av översiktlig natur och hänsyn måste tas till det vid utnyttjandet. Kartorna är inte lämpadeför detaljplanering eller vid studier av korta delperioder.

  • 268.
    Brandt, S. Anders
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Betydelse av höjdmodellers kvalitet vid översvämningsmodellering2009Inngår i: ULI aktuellt, ISSN 1654-6016, nr 1, s. 8-9Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 269.
    Brandt, S. Anders
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Conceptualization of hydraulic and sedimentary processes in downstream reaches during flushing of reservoirs2005Inngår i: Proceedings of the XXXI IAHR Congress [Elektronisk resurs]: Water engineering for the future : choices and challenges : COEX Seoul September 11-16, 2005, Seoul: Korea Water Resources Association , 2005, s. 2577-2588Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main focus of this paper is to describe the active hydraulic and sedimentary processes in downstream river reaches during flushing of sediments from reservoirs. During flushing extreme amounts of sediment may be released. Therefore, these processes are different than those downstream from dams and reservoirs not subjected to flushing. Hence, also the effects differ, which knowledge of may be of value for biologists, etc. During flushing of a reservoir a wave will be released to the downstream reaches. This wave can be divided into one water part and one sediment part. Initially they are in phase with each other, but with increased distance downstream from the dam, the transported sediment lags behind the water due to different traveling velocities. The paper treats when and where sedimentation occurs, and how this is related to the different traveling velocities of water and sediment. Also included are discussions on how the downstream effects during flushing differ from non-flushing effects, how visualization of effects can enhance both the analysis and communication with planners, politicians, etc., as well as discussions on how the studies of these effects can benefit from improved field-work methods.

  • 270.
    Brandt, S. Anders
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Resolution issues of elevation data during inundation modeling of river floods2005Inngår i: Proceedings of the XXXI IAHR Congress [Elektronisk resurs]: Water engineering for the future: choices and challenges. COEX Seoul September 11-16, 2005, Seoul: Korea Water Resources Association , 2005, s. 3573-3581Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A case study of the Eskilstuna River in Sweden is presented. This study is carried out within the project KRIS-GIS®, a Swedish initiative of handling crisis situations, including flooding. The purpose is to show how different resolutions in input elevation data affect the resulting inundation maps. Terrain elevation points at the sides of the river were gathered from an airborne laser altimetry survey, and river bed elevations were gathered from an echosounding survey. The terrain model was constructed in ArcView GIS as a triangulated irregular network (TIN), which served as the base for all later modeling. The hydraulic modeling was done as one-dimensional steady flow in HEC-RAS flow routing software. High-resolution elevation data resulted in better inundation delineation than did lowresolution elevation data. If the mean water discharge was used in the modeling and if the river is narrow, a low resolution could even lead to that the river itself would not be marked as inundated. At high water discharges, the river was usually inundated, but there was great uncertainty if the riparian areas really would be flooded or not. With steep side slopes, the delineation of inundation becomes more certain, while at gentler side slopes, the flow is distributed on a larger surface with a risk that the raster cells will be incorrectly marked regarding inundation. Finally, the use of high-resolution elevation data compared with lowresolution data, makes estimates of friction factor, Manning’s n, relatively more important for correct results in inundation studies.

  • 271.
    Brandt, S. Anders
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Översvämningsmodellering i GIS: betydelse av höjdmodellers upplösning applicerat på Eskilstunaån - ett delprojekt i KRIS-GIS®2005Rapport (Annet vitenskapelig)
    Abstract [sv]

    Under senare tid har översvämningar alltmer uppmärksammats av allmänhet, politiker, myndigheter och organisationer. Samtidigt har allt fler insett att det inte är en fråga om en översvämning kommer att ske utan när och hur stor den blir. Detta innebär att översvämningsrisker ständigt måste vara en närvarande del i politikers, planerares och krisberedskapsorganisationers arbete. Ett sätt att vara väl förberedd inför översvämningar är att ta fram översvämningsområden för olika stora vattenflöden. Därför har det inom projektet KRIS-GIS®, beställt och finansierat av Krisberedskapsmyndigheten, gjorts en mer detaljerad specialstudie över översvämningar kring Eskilstunaån. Tillförlitligheten hos framtagna översvämningsområden beror framför allt av två faktorer: korrekt vattenflödessimulering och korrekt beskrivning av terrängen. I denna studie har den endimensionella modellen HEC-RAS använts för flödessimuleringen och för beskrivning av terrängen har en flygburen 3D-laserskanning över området kring Eskilstunaån utförts. Dessutom har ekolodning utförts för att möjliggöra beskrivning av bottentopografin i Eskilstunaån. Samtliga höjddatapunkter kopplades ihop i ett GIS till ett triangulärt oregelbundet nätverk, TIN. Därefter lades sektioner tvärs över vattendraget och omgivande terräng. Dessa tvärsektioner tilldelades höjdvärden från TIN-modellen innan de exporterades till HEC-RAS. Fyra olika vattenföringar simulerades i HEC-RAS: medelvattenföringen på 23,7 m3/s, årsfloden på 70 m3/s, 100-årsflödet på 123 m3/s samt högsta beräknade flödet på 198 m3/s. Dessutom har det gjorts några alternativa körningar med varierande värden på Mannings n, dvs. markfriktion. Efter körningar i HEC-RAS, exporterades resulterande vattennivåer tillbaka till GISet där ett resultatraster skapades, där varje rastercell visades som översvämmad eller ej, och i förekommande fall översvämmat djup. Resultaten av översvämningsanalyserna visar att betydligt säkrare översvämningsprognoser nu kan göras när tillgång till terrängmodeller av hög kvalitet finns. Vid tidigare studier har Lantmäteriets höjddatabas använts, där höjder finns representerade med ett värde per 50-metersruta. Från att terrängmodellen har varit den begränsande faktorn övergår i stället en korrekt beskrivning av markens råhet eller friktion, uttryckt som Mannings n, till att vara den begränsande faktorn. Det rekommenderas därför att differentiera råhetsvärdena beroende på vilken markanvändningstyp som finns längs med vattendraget. Speciellt viktigt är detta i flacka områden. För Eskilstunaåns nordligaste delar är det viktigt att vattennivån i Mälaren bedöms korrekt. För att sprida och kunna dra nytta av resultaten framtagna i KRIS-GIS®-projektet rekommenderas det att färdiga översvämningspolygoner kan användas av kommuner, räddningstjänst osv. i deras arbete. De kan ringa eller automatiskt få information, från t.ex. SMHI eller vattenregleringsföretag, som innehåller upplysningar om förväntade flöden. Motsvarande polygon för förväntat flöde visas i ett GIS och direkt har man lägesbilden klart för sig. Utöver detta har även visualiseringsaspekter behandlats.

  • 272.
    Brandt, S. Anders
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Bergquist, Arne
    Lantmäteriet.
    Översvämningskarteringars tillförlitlighet2009Inngår i: Kart & Bildteknik (Mapping and Image Science), ISSN 1651-792X, nr 4, s. 33-35Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    I ett tidigare nummer av Kart & Bildteknik beskrevs ett pågående forskningsprojekt som försökte ta reda på om det finns en optimal kvalitet på geografisk information som underlag för detaljerad översvämningskartering (Bergquist, Brandt & Klang, 2008). Projektet är nu avslutat och avrapporterat i Brandt (2009) och Klang och Klang (2009). Av resultaten framgår bland annat hur mycket tillförlitligheten av en översvämningskartering minskar med graden av försämrad höjdmodell, vilken utgör ett av de viktigaste underlagen för en översvämningsanalys. I samband med EUs översvämningsdirektiv (Europaparlamentets och rådets direktiv, 2007) föranleder detta en diskussion om vilka översvämningskarteringar som krävs för att uppfylla direktivet.

  • 273.
    Brandt, S. Anders
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    Jiang, Bin
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för samhällsbyggnad.
    3D geovisualization as a communication and analysis tool in fluvial geomorphology2004Inngår i: Geoinformatics 2004: proceedings of the 12th International Conference on Geoinformatics - Geospatial Information Research: Bridging the Pacific and Atlantic, University of Gävle, Sweden, 7-9 June 2004, Gävle: Gävle University Press , 2004, s. 339-346Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The fields of hydrology and fluvial geomorphology get more and more attention in the general public. The reason for this is changed climate patterns with increased frequencies of storms and river flooding and as a result changed geomorphology and living conditions for the inhabitants of the area. With the development of 3D geovisualization, hydrological and geomorphological processes can be better simulated and visualized. Thus not only the domain specialists, but also the general public can appreciate very complex hydrological processes and resulting geomorphology. This is of great value since a high frequency of storms and flooding has been a big issue for politicians, planners, and the general public. It is in this sense that 3D geovisualization can be an important tool for analysis and communication. Complex hydrological and geomorphological processes can be effectively simulated and analyzed by the domain specialists while efficient and effective visualization provides a common platform for communication among domain specialists and the general public. This paper will discuss and illustrate these issues using a case study of geomorphology along the Reventazón River, downstream from the Cachí Reservoir in Costa Rica, due to the release of extreme amounts of sediment during flushing of the reservoir.

  • 274.
    Brandt, S. Anders
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Lim, Nancy J.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Visualising DEM-related flood-map uncertainties using a disparity-distance equation algorithm2016Inngår i: The spatial dimensions of water management: Redistribution of benefits and risks / [ed] A. H. Schumann, G. Blöschl, A. Castellarin, J. Dietrich, S. Grimaldi, U. Haberlandt, A. Montanari, D. Rosbjerg, A. Viglione, and S. Vorogushyn, Göttingen: Copernicus Publications on behalf of International Association of Hydrological Sciences (IAHS) , 2016, s. 153-159Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The apparent absoluteness of information presented by crisp-delineated flood boundaries can lead tomisconceptions among planners about the inherent uncertainties associated in generated flood maps. Even mapsbased on hydraulic modelling using the highest-resolution digital elevation models (DEMs), and calibrated withthe most optimal Manning’s roughness (n) coefficients, are susceptible to errors when compared to actual floodboundaries, specifically in flat areas. Therefore, the inaccuracies in inundation extents, brought about by thecharacteristics of the slope perpendicular to the flow direction of the river, have to be accounted for. Instead ofusing the typical Monte Carlo simulation and probabilistic methods for uncertainty quantification, an empiricalbaseddisparity-distance equation that considers the effects of both the DEM resolution and slope was used tocreate prediction-uncertainty zones around the resulting inundation extents of a one-dimensional (1-D) hydraulicmodel. The equation was originally derived for the Eskilstuna River where flood maps, based on DEM dataof different resolutions, were evaluated for the slope-disparity relationship. To assess whether the equation isapplicable to another river with different characteristics, modelled inundation extents from the Testebo Riverwere utilised and tested with the equation. By using the cross-sectional locations, water surface elevations, andDEM, uncertainty zones around the original inundation boundary line can be produced for different confidences.The results show that (1) the proposed method is useful both for estimating and directly visualising modelinaccuracies caused by the combined effects of slope and DEM resolution, and (2) the DEM-related uncertaintiesalone do not account for the total inaccuracy of the derived flood map. Decision-makers can apply it to alreadyexisting flood maps, thereby recapitulating and re-analysing the inundation boundaries and the areas that areuncertain. Hence, more comprehensive flood information can be provided when determining locations whereextra precautions are needed. Yet, when applied, users must also be aware that there are other factors that caninfluence the extent of the delineated flood boundary.

  • 275.
    Brandt, S. Anders
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Lim, Nancy Joy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Importance of river bank and floodplain slopes on the accuracy of flood inundation mapping2012Inngår i: River Flow 2012: Volume 2 / [ed] Rafael Murillo Muñoz, Leiden, The Netherlands: CRC Press / Balkema (Taylor & Francis) , 2012, s. 1015-1020Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Effective flood assessment and management depend on accurate models of flood events, which in turn are strongly affected by the quality of digital elevation models (DEMs). In this study, HEC-RAS was used to route one specificwater discharge through the main channel of the Eskilstuna River, Sweden. DEMs with various resolutions and accuracies were used to model the inundation. The results showed a strong positive relationship between the quality of theDEMand the extent of the inundation. However, evenDEMswith the highest resolution produced inaccuracies. In another case study, the Testebo River, the model settings could be calibrated, thanks to a surveyed old inundation event. However, even with the calibration efforts, the resulting inundation extents showed varying degrees of deviation from the surveyed flood boundaries. Therefore, it becomes clear that not only does the resolution of the DEM impact the quality of the results; also, the floodplain slope perpendicular to the river flow will impact the modelling accuracy. Flatter areas exhibited the greatest predictive uncertainties regardless of the DEM’s resolution. For perfectly flat areas, uncertainty becomes infinite.

  • 276.
    Brandt, Sven Anders
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS.
    Modeling and visualizing uncertainties of flood boundary delineation: algorithm for slope and DEM resolution dependencies of 1D hydraulic models2016Inngår i: Stochastic environmental research and risk assessment (Print), ISSN 1436-3240, E-ISSN 1436-3259, Vol. 30, nr 6, s. 1677-1690Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As flood inundation risk maps have become a central piece of information for both urban and risk management planning, also a need to assess the accuracies and uncertainties of these maps has emerged. Most maps show the inundation boundaries as crisp lines on visually appealing maps, whereby many planners and decision makers, among others, automatically believe the boundaries are both accurate and reliable. However, as this study shows, probably all such maps, even those that are based on high-resolution digital elevation models (DEMs), have immanent uncertainties which can be directly related to both DEM resolution and the steepness of terrain slopes perpendicular to the river flow direction. Based on a number of degenerated DEMs, covering areas along the Eskilstuna River, Sweden, these uncertainties have been quantified into an empirically-derived disparity distance equation, yielding values of distance between true and modeled inundation boundary location. Using the inundation polygon, the DEM, a value representing the DEM resolution, and the desired level of confidence as inputs in a new-developed algorithm that utilizes the disparity distance equation, the slope and DEM dependent uncertainties can be directly visualized on a map. The implications of this strategy should benefit planning and help reduce high costs of floods where infrastructure, etc., have been placed in flood-prone areas without enough consideration of map uncertainties.

  • 277.
    Brannigan, Liam
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Johnson, Helen
    Ligue, Camille
    Nycander, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Nilsson, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Generation of Subsurface Anticyclones at Arctic Surface Fronts due to a Surface Stress2017Inngår i: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 47, nr 11, s. 2653-2671Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Isolated anticyclones are frequently observed below the mixed layer in the Arctic Ocean. Some of these subsurface anticyclones are thought to originate at surface fronts. However, previous idealized simulations with no surface stress show that only cyclone–anticyclone dipoles can propagate away from baroclinically unstable surface fronts. Numerical simulations of fronts subject to a surface stress presented here show that a surface stress in the same direction as the geostrophic flow inhibits dipole propagation away from the front. On the other hand, a surface stress in the opposite direction to the geostrophic flow helps dipoles to propagate away from the front. Regardless of the surface stress at the point of dipole formation, these dipoles can be broken up on a time scale of days when a surface stress is applied in the right direction. The dipole breakup leads to the deeper anticyclonic component becoming an isolated subsurface eddy. The breakup of the dipole occurs because the cyclonic component of the dipole in the mixed layer is subject to an additional advection because of the Ekman flow. When the Ekman transport has a component oriented from the anticyclonic part of the dipole toward the cyclonic part then the cyclone is advected away from the anticyclone and the dipole is broken up. When the Ekman transport is in other directions relative to the dipole axis, it also leads to deviations in the trajectory of the dipole. A scaling is presented for the rate at which the surface cyclone is advected that holds across a range of mixed layer depths and surface stress magnitudes in these simulations. The results may be relevant to other regions of the ocean with similar near-surface stratification profiles.

  • 278.
    Brannigan, Liam
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU). University of Southampton, National Oceanography Centre, United Kingdom; University of Oxford, United Kingdom.
    Marshall, David P.
    Garabato, Alberto C. Naveira
    Nurser, A. J. George
    Kaiser, Jan
    Submesoscale Instabilities in Mesoscale Eddies2017Inngår i: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 47, nr 12, s. 3061-3085Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Submesoscale processes have been extensively studied in observations and simulations of fronts. Recent idealized simulations show that submesoscale instabilities also occur in baroclinic mesoscale cyclones and anticyclones. The instabilities in the anticyclone grow faster and at coarser grid resolution than in the cyclone. The instabilities lead to larger restratification in the anticyclone than in the cyclone. The instabilities also lead to changes in the mean azimuthal jet around the anticyclone from 2-km resolution, but a similar effect only occurs in the cyclone at 0.25-km resolution. A numerical passive tracer experiment shows that submesoscale instabilities lead to deeper subduction in the interior of anticyclonic than cyclonic eddies because of outcropping isopycnals extending deeper into the thermocline in anticyclones. An energetic analysis suggests that both vertical shear production and vertical buoyancy fluxes are important in anticyclones but primarily vertical buoyancy fluxes occur in cyclones at these resolutions. The energy sources and sinks vary azimuthally around the eddies caused by the asymmetric effects of the Ekman buoyancy flux. Glider transects of a mesoscale anticyclone in the Tasman Sea show that water with low stratification and high oxygen concentrations is found in an anticyclone, in a manner that may be consistent with the model predictions for submesoscale subduction in mesoscale eddies.

  • 279.
    Bratt, Anna
    et al.
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Andersson, L.
    Sandén, Per
    Linköpings universitet, Institutionen för tema. Linköpings universitet, Filosofiska fakulteten.
    Farmers questions and model answers on nitrogen leakage2003Artikkel i tidsskrift (Fagfellevurdert)
  • 280.
    Bratt, Anna
    et al.
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Graham, L. P.
    Sandén, Per
    Linköpings universitet, Institutionen för tema. Linköpings universitet, Filosofiska fakulteten.
    Potential changes to nutrient leaching from adaptation of Swedish agricultural production to climate change2003Artikkel i tidsskrift (Fagfellevurdert)
  • 281.
    Bratt, Anna-Lena
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Managing agricultural nutrient leaching within the EC Water Framework Directive in Sweden2003Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Agricultural management practices geared towards reducing nutrient leaching are in focus for the research presented in this thesis. Critical measures for reducing diffuse pollution from the agricultural sector depend on decisions of individual farmers. It is useful to take stock of what different stakeholders are actually doing to reduce nutrient leaching and analyze their reasoning before defining a new administrative process. Stakeholder perceptions about potentials and problems concerning management of agricultural practices are analyzed with a systems approach using various analytical methods, and put in relation to the implementation of EC Water Framework Directive in Sweden. The methods used include surveys, focus group interviews, model comparison, sensitivity analyses and analyses of climate change implications.

    The results indicate a general positive attitude among stakeholders towards the main characteristics of the newly introduced directive. They also reveal that a move towards a pro-active process was perceived as an additional positive factor for the improvement of water quality, where specific activities and measures are carried out according to planning based on local assessments. The respondents pointed out that a national approach would put necessary pressure on local politicians to define environmental objectives and provide resources to fulfil them. The current findings indicate that decision making for farmers is a complex procedure and that the different factors need to be addressed in order to obtain a change in agricultural practices.

    Consistent legislation that is clear about power and rights is fundamental for cooperation to function when volunteerism and enthusiasm are absent. Environmental and socio-economic conditions change constantly, and administration has to be flexible to be able to adapt. Having access to and being able to use relevant data is only one important factor for stakeholder involvement. To give farmers the opportunity to further develop production towards reduced nutrient losses, appropriate information provided in all the right arenas is crucial.

  • 282.
    Bratt, Anna-Lena
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Municipal officers on implementing the EU Water Framework Directive in Sweden regarding agricultural nutrient flows2004Inngår i: Local Environment, ISSN 1354-9839, Vol. 9, nr 1, s. 65-79Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The article analyses the perceptions at municipal level of potentials and problems in implementing integrated catchment management of water resources as proposed in the EU Water Framework Directive, expressed in views on how to reduce nutrient leakage from agricultural production. Heads of environmental authorities, spatial planners and environmental officers are among the professionals that will be key actors when implementing the WFD at the local level. Using a process of active focus group interviews, officials from municipal environmental offices studied, reflected upon and discussed the suggested plan concerning their part of implementing WFD. The municipal officers stressed certain conditions that have to be met to implement WFD in a sustainable manner. The most important conditions are clear environmental goals and management plans with support in legislation, which would put the necessary pressure upon local politicians to prioritize the WFD and take action. The respondents perceived the WFD would offer a changed approach in work routines with farmers towards partnerships for sustainable water resource management.

  • 283. Brauer, C. C.
    et al.
    Teuling, A. J.
    Overeem, A.
    van der Velde, Y.
    Hydrology and Quantitative Water Management Group, Wageningen University, Wageningen, The Netherlands.
    Hazenberg, P.
    Warmerdam, P. M. M.
    Uijlenhoet, R.
    Anatomy of extraordinary rainfall and flash flood in a Dutch lowland catchment2011Inngår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 15, s. 1991-2005Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    On 26 August 2010 the eastern part of The Netherlands and the bordering part of Germany were struck by a series of rainfall events lasting for more than a day. Over an area of 740 km(2) more than 120 mm of rainfall were observed in 24 h. This extreme event resulted in local flooding of city centres, highways and agricultural fields, and considerable financial loss. In this paper we report on the unprecedented flash flood triggered by this exceptionally heavy rainfall event in the 6.5 km(2) Hupsel Brook catchment, which has been the experimental watershed employed by Wageningen University since the 1960s. This study aims to improve our understanding of the dynamics of such lowland flash floods. We present a detailed hydrometeorological analysis of this extreme event, focusing on its synoptic meteorological characteristics, its space-time rainfall dynamics as observed with rain gauges, weather radar and a microwave link, as well as the measured soil moisture, groundwater and discharge response of the catchment. At the Hupsel Brook catchment 160 mm of rainfall was observed in 24 h, corresponding to an estimated return period of well over 1000 years. As a result, discharge at the catchment outlet increased from 4.4x10(-3) to nearly 5m(3) s(-1). Within 7 h discharge rose from 5x10(-2) to 4.5m(3) s(-1). The catchment response can be divided into four phases: (1) soil moisture reservoir filling, (2) groundwater response, (3) surface depression filling and surface runoff and (4) backwater feedback. The first 35mm of rainfall were stored in the soil without a significant increase in discharge. Relatively dry initial conditions (in comparison to those for past discharge extremes) prevented an even faster and more extreme hydrological response.

  • 284. Braun, Mattias
    et al.
    Schuler, Thomas
    Hock, Regine
    Brown, Ian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Jackson, Miriam
    Comparison of remote sensing derived glacier facies maps with distributed mass balance modelling at Engabreen, northern Norway.2007Inngår i: International Association of Hydrological Sciences: Red book series, nr 318, s. 126-134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract Calibration and validation of glacier mass balance models typically rely on mass balance data derived from measurements at individual points, often along altitudinal gradients, thus neglecting

    much of the spatial variability of mass balance. Remote sensing data can provide useful additional spatially distributed information, e.g. on surface conditions such as bare ice area, firn cover extent, or snow. We developed a semi-automated procedure to derive glacier-facies maps from Landsat satellite images, and applied it to Engabreen, an outlet glacier from the Svartisen ice cap in northern Norway. These maps, discriminating between firn, snow and ice surfaces, are then used as a reference for mass balance modelling. Facies information shows a general agreement with the available few field observations and results obtained by distributed mass balance modelling. We conclude that Earth Observation products provide a powerful, although as yet poorly exploited tool, for calibration and validation of distributed mass balance models.

  • 285.
    Bravo, Andrea G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Bouchet, Sylvain
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden..
    Tolu, Julie
    Umea Univ, Dept Ecol & Environm Sci, SE-90187 Umea, Sweden..
    Bjorn, Erik
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden..
    Mateos-Rivera, Alejandro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Molecular composition of organic matter controls methylmercury formation in boreal lakes2017Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, artikkel-id 14255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A detailed understanding of the formation of the potent neurotoxic methylmercury is needed to explain the large observed variability in methylmercury levels in aquatic systems. While it is known that organic matter interacts strongly with mercury, the role of organic matter composition in the formation of methylmercury in aquatic systems remains poorly understood. Here we show that phytoplankton-derived organic compounds enhance mercury methylation rates in boreal lake sediments through an overall increase of bacterial activity. Accordingly, in situ mercury methylation defines methylmercury levels in lake sediments strongly influenced by planktonic blooms. In contrast, sediments dominated by terrigenous organic matter inputs have far lower methylation rates but higher concentrations of methylmercury, suggesting that methylmercury was formed in the catchment and imported into lakes. Our findings demonstrate that the origin and molecular composition of organic matter are critical parameters to understand and predict methylmercury formation and accumulation in boreal lake sediments.

  • 286. Breinl, Korbinian
    Driving a lumped hydrological model with precipitation output from weather generators of different complexity2016Inngår i: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 61, nr 8, s. 1395-1414Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper deals with the question of whether a lumped hydrological model driven with lumped daily precipitation time series from a univariate single-site weather generator can produce equally good results compared to using a multivariate multi-site weather generator, where synthetic precipitation is first generated at multiple sites and subsequently lumped. Three different weather generators were tested: a univariate “Richardson type” model, an adapted univariate Richardson type model with an improved reproduction of the autocorrelation of precipitation amounts and a semi-parametric multi-site weather generator. The three modelling systems were evaluated in two Alpine study areas by comparing the hydrological output with respect to monthly and daily statistics as well as extreme design flows. The application of a univariate Richardson type weather generator to lumped precipitation time series requires additional attention. Established parametric distribution functions for single-site precipitation turned out to be unsuitable for lumped precipitation time series and led to a large bias in the hydrological simulations. Combining a multi-site weather generator with a hydrological model produced the least bias.

  • 287.
    Breinl, Korbinian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Di Baldassarre, Giuliano
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Girons Lopez, Marc
    Department of Geography, University of Zurich.
    Hagenlocher, Michael
    Institute for Environment and Human Security, United Nations University (UNU-EHS).
    Vico, Giulia
    Department of Crop Production Ecology, Swedish University of Agricultural Sciences.
    Rutgersson, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Can weather generation capture precipitation patterns across different climates, spatial scales and under data scarcity?2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 5449Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stochastic weather generators can generate very long time series of weather patterns, which are indispensable in earth sciences, ecology and climate research. Yet, both their potential and limitations remain largely unclear because past research has typically focused on eclectic case studies at small spatial scales in temperate climates. In addition, stochastic multi-site algorithms are usually not publicly available, making the reproducibility of results difficult. To overcome these limitations, we investigated the performance of the reduced-complexity multi-site precipitation generator TripleM across three different climatic regions in the United States. By resampling observations, we investigated for the first time the performance of a multi-site precipitation generator as a function of the extent of the gauge network and the network density. The definition of the role of the network density provides new insights into the applicability in data-poor contexts. The performance was assessed using nine different statistical metrics with main focus on the inter-annual variability of precipitation and the lengths of dry and wet spells. Among our study regions, our results indicate a more accurate performance in wet temperate climates compared to drier climates. Performance deficits are more marked at larger spatial scales due to the increasing heterogeneity of climatic conditions.

  • 288. Breinl, Korbinian
    et al.
    Strasser, Ulrich
    Bates, Paul D
    Kienberger, Stefan
    A joint modelling framework for daily extremes of river discharge and precipitation in urban areas2015Inngår i: Journal of Flood Risk Management, ISSN 1753-318X, E-ISSN 1753-318XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Human settlements are often at risk from multiple hydro-meteorological hazards, which include fluvial floods, short-time extreme precipitation (leading to ‘pluvial’ floods) or coastal floods. In the past, considerable scientific effort has been devoted to assessing fluvial floods. Only recently have methods been developed to assess the hazard and risk originating from pluvial phenomena, whereas little effort has been dedicated to joint approaches. The aim of this study was to develop a joint modelling framework for simulating daily extremes of river discharge and precipitation in urban areas. The basic framework is based on daily observations coupled with a novel precipitation disaggregation algorithm using nearest neighbour resampling combined with the method of fragments to overcome data limitations and facilitate its transferability. The framework generates dependent time series of river discharge and urban precipitation that allow for the identification of fluvial flood days (daily peak discharge), days of extreme precipitation potentially leading to pluvial phenomena (maximum hourly precipitation) and combined fluvial–pluvial flood days (combined time series). Critical thresholds for hourly extreme precipitation were derived from insurance and fire service data.

  • 289. Breinl, Korbinian
    et al.
    Turkington, Thea
    Stowasser, Markus
    Stochastic generation of multi-site daily precipitation for applications in risk management2013Inngår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 498, s. 23-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Unlike single-site precipitation generators, multi-site precipitation generators make it possible to reproduce the space–time variation of precipitation at several sites. The extension of single-site approaches to multiple sites is a challenging task, and has led to a large variety of different model philosophies for multi-site models. This paper presents an alternative semi-parametric multi-site model for daily precipitation that is straightforward and easy to implement. Multi-site precipitation occurrences are simulated with a univariate Markov process, removing the need for individual Markov models at each site. Precipitation amounts are generated by first resampling observed values, followed by sampling synthetic precipitation amounts from parametric distribution functions. These synthetic precipitation amounts are subsequently reshuffled according to the ranks of the resampled observations in order to maintain important statistical properties of the observation network. The proposed method successfully combines the advantages of non-parametric bootstrapping and parametric modeling techniques. It is applied to two small rain gauge networks in France (Ubaye catchment) and Austria/Germany (Salzach catchment) and is shown to well reproduce the observations. Limitations of the model relate to the bias of the reproduced seasonal standard deviation of precipitation and the underestimation of maximum dry spells. While the lag-1 autocorrelation is well reproduced for precipitation occurrences, it tends to be underestimated for precipitation amounts. The model can generate daily precipitation amounts exceeding the ones in the observations, which can be crucial for risk management related applications. Moreover, the model deals particularly well with the spatial variability of precipitation. Despite its straightforwardness, the new concept makes a good alternative for risk management related studies concerned with producing daily synthetic multi-site precipitation time series.

  • 290.
    Brentrup, Jennifer A.
    et al.
    Miami Univ, Dept Biol, Oxford, OH 45056 USA..
    Williamson, Craig E.
    Miami Univ, Dept Biol, Oxford, OH 45056 USA..
    Colom-Montero, William
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Eckert, Werner
    Yigal Allon Kinneret Limnol Lab, Israel Oceanog & Limnol Res, Migdal, Israel..
    de Eyto, Elvira
    Inst Marine, Newport, Mayo, Ireland..
    Grossart, Hans-Peter
    Leibniz Inst Freshwater Ecol & Inland Fisheries I, Dept Expt Limnol, Stechlin, Germany.;Univ Potsdam, Inst Biochem & Biol, Potsdam, Germany..
    Huot, Yannick
    Univ Sherbrooke, Dept Geomat Appl, Sherbrooke, PQ, Canada..
    Isles, Peter D. F.
    Univ Vermont, Rubenstein Sch Environm & Nat Resources, Burlington, VT USA..
    Knoll, Lesley B.
    Univ Minnesota, Itasca Biol Stn, Lake Itasca, MN USA..
    Leach, Taylor H.
    Miami Univ, Dept Biol, Oxford, OH 45056 USA..
    McBride, Chris G.
    Univ Waikato, Environm Res Inst, Waikato, New Zealand..
    Pierson, Don
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Pomati, Francesco
    Swiss Fed Inst Aquat Sci & Technol, Dept Aquat Ecol, Dubendorf, Switzerland..
    Read, Jordan S.
    US Geol Survey, Ctr Integrated Data Analyt, Middleton, WI USA..
    Rose, Kevin C.
    Rensselaer Polytech Inst, Dept Biol Sci, Troy, NY USA..
    Samal, Nihar R.
    Univ New Hampshire, Earth Syst Res Ctr, Durham, NH 03824 USA..
    Staehr, Peter A.
    Aarhus Univ, Dept Biosci, Roskilde, Denmark..
    Winslow, Luke A.
    US Geol Survey, Ctr Integrated Data Analyt, Middleton, WI USA..
    The potential of high-frequency profiling to assess vertical and seasonal patterns of phytoplankton dynamics in lakes: an extension of the Plankton Ecology Group (PEG) model2016Inngår i: INLAND WATERS, ISSN 2044-2041, E-ISSN 2044-205X, Vol. 6, nr 4, s. 565-580Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of high-frequency sensors on profiling buoys to investigate physical, chemical, and biological processes in lakes is increasing rapidly. Profiling buoys with automated winches and sensors that collect high-frequency chlorophyll fluorescence (ChlF) profiles in 11 lakes in the Global Lake Ecological Observatory Network (GLEON) allowed the study of the vertical and temporal distribution of ChlF, including the formation of subsurface chlorophyll maxima (SSCM). The effectiveness of 3 methods for sampling phytoplankton distributions in lakes, including (1) manual profiles, (2) single-depth buoys, and (3) profiling buoys were assessed. High-frequency ChlF surface data and profiles were compared to predictions from the Plankton Ecology Group (PEG) model. The depth-integrated ChlF dynamics measured by the profiling buoy data revealed a greater complexity that neither conventional sampling nor the generalized PEG model captured. Conventional sampling techniques would have missed SSCM in 7 of 11 study lakes. Although surface-only ChlF data underestimated average water column ChlF, at times by nearly 2-fold in 4 of the lakes, overall there was a remarkable similarity between surface and mean water column data. Contrary to the PEG model's proposed negligible role for physical control of phytoplankton during the growing season, thermal structure and light availability were closely associated with ChlF seasonal depth distribution. Thus, an extension of the PEG model is proposed, with a new conceptual framework that explicitly includes physical metrics to better predict SSCM formation in lakes and highlight when profiling buoys are especially informative.

  • 291. Breuer, L.
    et al.
    Huisman, J. A.
    Willems, P.
    Bormann, H.
    Bronstert, A.
    Croke, B. F. W.
    Frede, H. -G
    Graeff, T.
    Hubrechts, L.
    Jakeman, A. J.
    Kite, G.
    Lanini, J.
    Leavesley, G.
    Lettenmaier, D. P.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Seibert, J.
    Sivapalan, M.
    Viney, N. R.
    Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM). I: Model intercomparison with current land use2009Inngår i: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 32, nr 2, s. 129-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper introduces the project on 'Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM)' that aims at investigating the envelope of predictions on changes in hydrological fluxes due to land use change. As part of a series of four papers, this paper outlines the motivation and setup of LUCHEM, and presents a model intercomparison for the present-day simulation results. Such an intercomparison provides a valuable basis to investigate the effects of different model structures on model predictions and paves the ground for the analysis of the performance of multi-model ensembles and the reliability of the scenario predictions in companion papers. in this study, we applied a set of 10 lumped, semi-lumped and fully distributed hydrological models that have been previously used in land use change studies to the low mountainous Dill catchment. Germany. Substantial differences in model performance were observed with Nash-Sutcliffe efficiencies ranging from 0.53 to 0.92. Differences in model performance were attributed to (1) model input data, (2) model calibration and (3) the physical basis of the models. The models were applied with two sets of input data: an original and a homogenized data set. This homogenization of precipitation, temperature and leaf area index was performed to reduce the variation between the models. Homogenization improved the comparability of model simulations and resulted in a reduced average bias, although some variation in model data input remained. The effect of the physical differences between models on the long-term water balance was mainly attributed to differences in how models represent evapotranspiration. Semi-lumped and lumped conceptual models slightly outperformed the fully distributed and physically based models. This was attributed to the automatic model calibration typically used for this type of models. Overall, however, we conclude that there was no superior model if several measures of model performance are considered and that all models are suitable to participate in further multi-model ensemble set-ups and land use change scenario investigations. (C) 2008 Elsevier Ltd. All rights reserved.

  • 292. Breuer, L.
    et al.
    Huisman, J. A.
    Willems, P.
    Bormann, H.
    Bronstert, A.
    Croke, B. F. W.
    Frede, H. G.
    Graff, T.
    Hubrechts, L.
    Jakeman, A. J.
    Kite, G.
    Lanini, J.
    Leavesley, G.
    Lettenmaier, D. P.
    Lindstrom, G.
    Seibert, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Sivapalan, M.
    Viney, N. R.
    Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM). I: Model intercomparison with current land use2009Inngår i: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 32, nr 2, s. 129-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper introduces the project on 'Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM)' that aims at investigating the envelope of predictions on changes in hydrological fluxes due to land use change. As part of a series of four papers, this paper outlines the motivation and setup of LUCHEM, and presents a model intercomparison for the present-day simulation results. Such an intercomparison provides a valuable basis to investigate the effects of different model structures on model predictions and paves the ground for the analysis of the performance of multi-model ensembles and the reliability of the scenario predictions in companion papers. in this study, we applied a set of 10 lumped, semi-lumped and fully distributed hydrological models that have been previously used in land use change studies to the low mountainous Dill catchment. Germany. Substantial differences in model performance were observed with Nash-Sutcliffe efficiencies ranging from 0.53 to 0.92. Differences in model performance were attributed to (1) model input data, (2) model calibration and (3) the physical basis of the models. The models were applied with two sets of input data: an original and a homogenized data set. This homogenization of precipitation, temperature and leaf area index was performed to reduce the variation between the models. Homogenization improved the comparability of model simulations and resulted in a reduced average bias, although some variation in model data input remained. The effect of the physical differences between models on the long-term water balance was mainly attributed to differences in how models represent evapotranspiration. Semi-lumped and lumped conceptual models slightly outperformed the fully distributed and physically based models. This was attributed to the automatic model calibration typically used for this type of models. Overall, however, we conclude that there was no superior model if several measures of model performance are considered and that all models are suitable to participate in further multi-model ensemble set-ups and land use change scenario investigations.

  • 293. Brigode, Pierre
    et al.
    Brissette, Francois
    Nicault, Antoine
    Perreault, Luc
    Kuentz, Anna
    SMHI, Samhälle och säkerhet.
    Mathevet, Thibault
    Gailhard, Joel
    Streamflow variability over the 1881-2011 period in northern Quebec: comparison of hydrological reconstructions based on tree rings and geopotential height field reanalysis2016Inngår i: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 12, nr 9, s. 1785-1804Artikkel i tidsskrift (Fagfellevurdert)
  • 294. Bring, A.
    et al.
    Fedorova, I.
    Dibike, Y.
    Hinzman, L.
    Mård, Johanna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Mernild, S. H.
    Prowse, T.
    Semenova, O.
    Stuefer, S. L.
    Woo, M-K
    Arctic terrestrial hydrology: A synthesis of processes, regional effects, and research challenges2016Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, nr 3, s. 621-649Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Terrestrial hydrology is central to the Arctic system and its freshwater circulation. Water transport and water constituents vary, however, across a very diverse geography. In this paper, which is a component of the Arctic Freshwater Synthesis, we review the central freshwater processes in the terrestrial Arctic drainage and how they function and change across seven hydrophysiographical regions (Arctic tundra, boreal plains, shield, mountains, grasslands, glaciers/ice caps, and wetlands). We also highlight links between terrestrial hydrology and other components of the Arctic freshwater system. In terms of key processes, snow cover extent and duration is generally decreasing on a pan-Arctic scale, but snow depth is likely to increase in the Arctic tundra. Evapotranspiration will likely increase overall, but as it is coupled to shifts in landscape characteristics, regional changes are uncertain and may vary over time. Streamflow will generally increase with increasing precipitation, but high and low flows may decrease in some regions. Continued permafrost thaw will trigger hydrological change in multiple ways, particularly through increasing connectivity between groundwater and surface water and changing water storage in lakes and soils, which will influence exchange of moisture with the atmosphere. Other effects of hydrological change include increased risks to infrastructure and water resource planning, ecosystem shifts, and growing flows of water, nutrients, sediment, and carbon to the ocean. Coordinated efforts in monitoring, modeling, and processing studies at various scales are required to improve the understanding of change, in particular at the interfaces between hydrology, atmosphere, ecology, resources, and oceans.

  • 295.
    Bring, Arvid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Arctic Climate and Water Change: Information Relevance for Assessment and Adaptation2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The Arctic is subject to growing economic and political interest. Meanwhile, its water and climate systems are in rapid transformation. Relevant and accessible information about water and climate is therefore vital to detect, understand and adapt to the changes. This thesis investigates hydrological monitoring systems, climate model data, and our understanding of hydro-climatic change, for adaptation to water system changes in the Arctic. Results indicate a lack of harmonized water chemistry data, which may impede efforts to understand transport and origin of key waterborne constituents. Further development of monitoring cannot rely only on a reconciliation of observations and projections on where climate change will be the most severe, as they diverge in this regard. Climate model simulations of drainage basin temperature and precipitation have improved between two recent model generations, but large inaccuracies remain for precipitation projections. Late 20th-century discharge changes in major Arctic rivers generally show excess of water relative to precipitation changes. This indicates a possible contribution of stored water from permafrost or groundwater to sea level rise. The river contribution to the increasing Arctic Ocean freshwater inflow matches that of glaciers, which underlines the importance of considering all sources when assessing change. To provide adequate information for research and policy, Arctic hydrological and hydrochemical monitoring needs to be extended, better integrated and made more accessible. This especially applies to hydrochemistry monitoring, where a more complete set of monitored basins is motivated, including a general extension for the large unmonitored areas close to the Arctic Ocean. Improvements in climate model parameterizations are needed, in particular for precipitation projections. Finally, further water-focused data and modeling efforts are required to resolve the source of excess discharge in Arctic rivers.

  • 296.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Divergent relevance and prioritization basis for hydro-climatic change monitoring in the Arctic2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Climate change affects society and the Earth System largely through water cycle changes, such as altered precipitation patterns and increased drought and flood pressures. In the Arctic, which undergoes a particularly large and rapid environmental transformation, information on water cycle changes is crucial to plan for societal adaptation. A prioritization strategy is then needed for how (where and when) monitoring should be focused to get the most relevant information and data on Arctic hydro-climatic change with limited available resources. We investigate different possible strategies for a geographic prioritization of hydro-climatic change monitoring in the Arctic. Results show conflicting prioritization basis across 14 major Arctic hydrological basins. The current monitoring density distribution is relevant for the so far observed but not for the projected future changes in Arctic climate. The present and the projected future hot-spots of greatest climate change differ, so that major spatial shifts must be anticipated in the future with regard to climate change severity across the Arctic. Important temporal shifts must further be anticipated in several major Arctic basins with currently decreasing but expected future increasing precipitation.

  • 297.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hydro-climatic change indications of Arctic permafrost thawing2012Konferansepaper (Fagfellevurdert)
  • 298.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hydro-climatic changes and their monitoring in the Arctic: Observation-model comparisons and prioritization options for monitoring development2013Inngår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 492, s. 273-280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Arctic undergoes particularly large and rapid hydro-climatic changes, and information on hydrological responses to these changes is crucial to plan for societal adaptation. We investigate hydro-climatic change severity and monitoring in 14 major hydrological basins across the pan-Arctic, in view of different possible strategies for their monitoring prioritization. Results show that the current distribution of monitoring density in these basins is more relevant for so far observed precipitation changes than for observed temperature changes, or for projected future temperature and precipitation changes. Furthermore, present and projected future hot-spots of greatest hydro-climatic change differ spatially, so that major spatial shifts must occur in the future among the different Arctic basins in order for observations and climate model projections to converge with regard to hydro-climatic change severity. Also temporally, observation-model convergence requires that important change direction shifts occur in major Arctic basins, which have currently decreasing precipitation while model projections imply future increasing precipitation within them. Different prioritization options for rational development of hydro-climatic monitoring can be argued for based on the present results. The divergent prioritization options imply a need for an explicit strategy for achieving certain information goals, which must be selected from a larger set of different possible goals based on societal importance.

  • 299.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hydrological and hydrochemical observation status in the pan-Arctic drainage basin2009Inngår i: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 28, s. 327-338Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to identify and understand the ongoing changes in the Arctic hydrological cycle, and the impacts on the Arctic Ocean, timely and open access to water and water-chemistry data is essential. By synthesizing and analysing all openly accessible water-discharge and water-quality data, we present an updated, quantitative picture of the status of observational data on hydrological and hydrochemical fluxes from the pan-Arctic drainage basin (PADB) to the ocean. We identify and compare the characteristics of monitored and unmonitored areas, and the differences between them, across the continents in the PADB. Results indicate significant gaps in monitoring data for water chemistry, in particular for high-latitude near-coastal areas. The differences in characteristics between monitored and unmonitored areas may bias assessments of hydrological and hydrochemical fluxes to the Arctic Ocean. The reliable identification and understanding of important biogeochemical processes in the PADB require extended monitoring, particularly in high-latitude permafrost ground, and more ready access to harmonized and integrated hydrochemical data.

  • 300.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Information relevance for scenarios of Arctic climate and water change2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Relevant and accessible information about Arctic water and climate change is vital for scenario projection and adaptation in the rapidly changing region. We investigate the adequacy and relevance of hydrological monitoring systems, climate model data and hydro-climatic change understanding for formulation of change scenarios and adaptation to water system changes in the Arctic. Our results indicate a lack of harmonized water chemistry data for the pan-Arctic drainage basin, which may impede efforts at understanding transport and origin of key waterborne constituents and projecting their changes of relevance for water, climate and ecosystems. Furthermore, divergent distribution of observed and projected climate change severity poses challenges to prioritizing monitoring development. Climate model projections of drainage basin temperature and precipitation have improved between two successive model generations, but large inaccuracies remain for projected precipitation scenarios. Late 20th-century discharge changes in major Arctic rivers generally show excess of water relative to observed precipitation changes, indicating a possible contribution of stored water from permafrost or groundwater, even when considering data uncertainty on Arctic precipitation. To provide adequate information for research and policy, Arctic hydrological and hydrochemical monitoring needs to be extended, better integrated and more accessible, specifically regarding hydrochemistry with a more complete set of basins, and in general for the large unmonitored areas closer to the Arctic Ocean. Improvements in climate model parameterizations are needed in particular for precipitation projections, and further water-focused data and modeling efforts are required to resolve the source of excess discharge in Arctic rivers. 

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