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  • 151.
    Häggström, Martin
    et al.
    SMHI, Core Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Sandoval, Luz Amelia
    Vega, Maria Elvira
    Application of the HBV model to the upper Río Cauca basin1988Report (Other academic)
    Abstract [en]

    The work described in this report is part of a collaboration project between Corporación Autónoma Regional del Cauca (CVC), Colombia, and the Swedish Meteorological and Hydrological Institute (SMHI)

    CVC is an entity, whose main objective is to promote the economic and social development of the upper Cauca basin in the provinces of Cauca and Valle as well as of part of the Colombian Pacific region. One specific objective is to regulate the river, Rio Cauca, for flood control, hydropower generation and for pollution alleviation.

    The collaboration project deals with the application of the conceptual HBV model to the upper Rio Cauca. The work was started in February 1987 and completed in June 1988. The project was financially supported by the Swedish Agency for Technical and Economic Cooperation (BITS).

  • 152. Iliopoulou, Theano
    et al.
    Aguilar, Cristina
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Bermudez, Maria
    Bezak, Nejc
    Ficchi, Andrea
    Koutsoyiannis, Demetris
    Parajka, Juraj
    Jose Polo, Maria
    Thirel, Guillaume
    Montanari, Alberto
    A large sample analysis of European rivers on seasonal river flow correlation and its physical drivers2019In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 23, no 1, p. 73-91Article in journal (Refereed)
  • 153. Jacob, Daniela
    et al.
    Kotova, Lola
    Teichmann, Claas
    Sobolowski, Stefan P.
    Vautard, Robert
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Koutroulis, Aristeidis G.
    Grillakis, Manolis G.
    Tsanis, Ioannis K.
    Damm, Andrea
    Sakalli, Abdulla
    van Vliet, Michelle T. H.
    Climate Impacts in Europe Under+1.5 degrees C Global Warming2018In: Earth's Future, ISSN 1384-5160, E-ISSN 2328-4277, Vol. 6, no 2, p. 264-285Article in journal (Refereed)
  • 154. Jaramillo, Fernando
    et al.
    Cory, Neil
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Laudon, Hjalmar
    van der Velde, Ype
    Hasper, Thomas B.
    Teutschbein, Claudia
    Uddling, Johan
    Dominant effect of increasing forest biomass on evapotranspiration: interpretations of movement in Budyko space2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, no 1, p. 567-580Article in journal (Refereed)
  • 155.
    Johansson, Barbro
    et al.
    SMHI, Professional Services.
    Edström, Magnus
    SMHI, Core Services.
    Losjö, Katarina
    SMHI, Professional Services.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Analys och beräkning av snösmältningsförlopp1998Report (Other academic)
    Abstract [sv]

    I HBV-modellen, liksom i många andra begreppsmässiga modeller används en enkel graddagmetod för snösmältningsberäkningar. Det har erfarenhetsmässigt visat sig svårt att med mer komplicerade uttryck för snösmältningen förbättra beräkningen av avrinning. Samtidigt har vi sett att de fel som uppstår i HBV-modellen i samband med snösmältning ibland uppträder samtidigt i flera områden. De är alltså inte slumpmässiga, och kan inte enbart förklaras av osäkerheten i de indata som används rutinmässigt. Det tycks som om det i de aktuella vädersituationerna finns en eller flera faktorer som modellen inte tar hänsyn till. I stället för att testa olika komplicerade modeller för snösmältning har, i det här projektet, ett försök gjorts att angripa problemet från motsatt håll. Vi har försökt hitta en koppling mellan meteorologiska förhållanden och modellfel. Speciellt har vi tittat på temperaturens höjdberoende. Studien har genomförts i sex avrinningsområden i den svenska fjällkedjan, och med data från 1975 till 1997.

    För temperaturens höjdberoende utnyttjades data från tre näraliggande stationspar på olika höjd. I HBV-modellen antas vanligen att temperaturen avtar med 0.6°C per 100m. I verkligheten visade sig temperaturgradienten variera kraftigt, och även vid temperaturer över 0°C kunde det inträffa att temperaturen ökade med höjden. Ett svagt samband kunde skönjas mellan temperaturens dygnsvariation vid den lägsta stationen och temperaturgradienten. Däremot gav det inga generella förbättringar i simulerad avrinning att föra in en varierande temperaturgradient i HBV-modellen.

    Vid jämförelserna mellan volymfel och meteorologiska förhållanden kunde endast tendenser till samband påvisas, och då framför allt under vårflodens start. Det tycks som om HBV-modellen oftare underskattar volymen när det blåser mycket, är hög luftfuktighet och/eller molnigt väder, och att volymen oftare överskattas när det är varmt och vackert väder. Detta är i överensstämmelse med energibalansekvationen, med tillförseln av sensibelt värme vid höga vindhastigheter och latent värme vid hög luftfuktighet. Vid vackert väder är det däremot möjligt att en del av den tillgängliga energin går till avdunstning i stället för smältning.

    Resultaten visar återigen att det är svårt att hitta vägar att förbättra beräkning av snösmältning på avrinningsområdesskala. Ett viktigt skäl är osäkerheten i indata. Data från ett fåtal meteorologiska stationer på låg höjd skall extrapoleras över stora avstånd, både vertikalt och horisontellt. De fel som orsakas av detta gör det svårt att särskilja fel som orsakas av en oriktig fysikalisk beskrivning av processerna. En annan generell svårighet vid all modellutveckling är problemet med kompenserande fel. Det innebär att vissa komponenter i ursprungsmodellen oftast innehåller förenklingar eller brister som kompenseras genom justeringar i andra delar av modellen. Slutresultatet kan ofta bli bra, men det kan bli svårt att förbättra modellen eftersom en bättre beskrivning av en viss del kan ta bort denna kompenserande verkan. Därmed blir slutresultatet sämre trots att en enskild process beskrivs mer realistiskt.

  • 156.
    Johansson, Barbro
    et al.
    SMHI, Professional Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Yacoub, Tahsin
    SMHI, Core Services.
    Haase, Günther
    SMHI, Research Department, Atmospheric remote sensing.
    Jacobsson, Karin
    SMHI, Professional Services.
    Sanner, Håkan
    SMHI, Core Services.
    Översvämningsprognoser i områden med ofullständiga data: Metodutveckling och utvärdering2007Report (Other academic)
    Abstract [sv]

    Rapporten redovisar slutresultat från projektet ”Översvämningsprognoser Utveckling av metoder för ett rikstäckande system för vattenförings- och vattenståndsprognoser”. Projektet har i huvudsak varit finansierat av Räddningsverket, numera MSB, (Myndigheten för Samhällsskydd och Beredskap), men har även utnyttjat resultat från näraliggande projekt finansierade av Elforsk, SMHI och EU.I ett rikstäckande system måste prognoser göras för vattendrag där det saknas detaljerad information om avrinningsområdets och älvfårans egenskaper. Modeller kan inte tillämpas och verifieras på samma sätt som i områden med god datatillgång och tillgång till tidsserier med observerad vattenföring. Eftersom beräkningarna inte kan verifieras mot observationer blir det extra viktigt med bra nederbördsinformation och att kunna ge ett mått på osäkerheten i prognosen. Projektet har dels arbetat med metodutveckling, dels med en omfattande utvärdering av data och beräkningsresultat. En pilotstudie gjordes för flödet sommaren 2004 i Lagan/Ljungby. Fokus har varit på följande områden:- Utveckling och utvärdering av en metodik för att utnyttja meteorologiska och hydrologiska sannolikhetsprognoser- Utvärdering och minimering av osäkerheten i hydrologiska (vattenföring) och hydrauliska (vattenstånd) prognosmodeller.- Utveckling och utvärdering av metoder för att utnyttja radarobservationer av nederbörd.Projektet har visat att det är möjligt att göra vattenståndsprognoser med rimlig noggrannhet, utgående från data som finns tillgängliga i ett rikstäckande system. Tillgång till bra nederbördsinformation för dagarna före prognosen är viktig, speciellt i sjörika system med ett långsamt förlopp. För att kunna göra sannolikhetsprognoser räcker det inte att ta hänsyn till osäkerheten i den meteorologiska prognosen genom att direkt utnyttja meteorologiska ensembleprognoser. Spridningen i de meteorologiska nederbördsprognoserna är inte tillräcklig och osäkerheten i den hydrologiska modellen måste beaktas.De projektresultat som inom det närmaste året kommer att utnyttjas i ett rikstäckande system är de som är relaterade till hydrologisk modellering och sannolikhetsprognoser. Arbetet med att utveckla metoder för att utnyttja radarinformation i operationell skattning av arealnederbörd fortgår. Fallstudier har visat att vattenståndsprognoser kan göras med modeller baserad på översiktlig information om topografi och tvärsektioner i vattendragen. Däremot är det tidsödande att sätta upp en hydraulisk modell för en godtycklig älvsträcka. Tills vidare är det realistiskt att anta att vattenståndsprognoser främst kommer att göras i vattendrag som ingått i den översiktliga översvämningskarteringen.

  • 157.
    Johnell, Anna
    et al.
    SMHI, Professional Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Deterministic evaluation of ensemble streamflow predictions in Sweden2007In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 38, no 4-5, p. 441-450Article in journal (Refereed)
    Abstract [en]

    A system for ensemble streamflow prediction, ESP, has been operational at SMHI since July 2004, based on 50 meteorological ensemble forecasts from ECMWF. Hydrological ensemble forecasts are produced daily for 51 basins in Sweden. All ensemble members, as well as statistics (minimum, 25% quartile, median, 75% quartile and maximum), are stored in a database. This paper presents an evaluation of the first 18 months of ESP median forecasts from this system, and in particular their performance in comparison with today's categorical forecast. The evaluation was made in terms of three statistical measures: bias B, root mean square error RMSE and absolute peak flow error PE. For ESP forecasts the bias ranged between -20% and 80% with a systematic overestimation for Sweden as a whole. A comparison between bias in input precipitation and ESP output, respectively, revealed only a weak relationship, but streamflow overestimation is likely related mainly to model properties. The results from the streamflow forecast comparison showed that the ESP median in deterministic terms performs overall as well as the presently used categorical forecast. Further, ESP has the advantage of providing at least a qualitative measure of the uncertainty in the forecasts, with probability forecasts being the ultimate goal.

  • 158. Jonsson, A.
    et al.
    Andersson, Lotta
    SMHI, Core Services.
    Alkan-Olsson, J.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    How participatory can participatory modeling be?: Degrees of influence of stakeholder and expert perspectives in six dimensions of participatory modeling2007In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 56, no 1, p. 207-214Article in journal (Refereed)
    Abstract [en]

    The authors are involved in a project aiming at the development of a methodology for participatory modeling as a tool for public participation in water resource management. In this paper, some examples of different degrees of stakeholder influence in six key dimensions of participatory modeling are identified and discussed. Arnstein's (A ladder of citizen participation. Journal of the American Institute of Planners, 1969, 4, 216-224) critical discussion of different degrees of "real" decision-making power is taken as a point of departure to assess possible degrees of stakeholder influence. Can we as participatory modelers be sure that we are really inviting our research objects to an equal communicative relationship where local perspectives, knowledge and priorities are respected to the same extent as central and/or expert perspectives? This paper presents an approach that could be used as a tool for structured reflection to avoid unreflective tendencies towards expert knowledge dominance and low degree of stakeholders' real influence over the process.

  • 159. Jose Perez-Palazon, Maria
    et al.
    Pimentel, Rafael
    SMHI, Research Department, Hydrology.
    Jose Polo, Maria
    Climate Trends Impact on the Snowfall Regime in Mediterranean Mountain Areas: Future Scenario Assessment in Sierra Nevada (Spain)2018In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 10, no 6, article id 720Article in journal (Refereed)
  • 160. Juston, John
    et al.
    Jansson, Per-Erik
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    Rating curve uncertainty and change detection in discharge time series: case study with 44-year historic data from the Nyangores River, Kenya2014In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, no 4, p. 2509-2523Article in journal (Refereed)
    Abstract [en]

    The intersection of the developing topic of rating curve and discharge series uncertainty with the topic of hydrological change detection (e.g., in response to land cover or climatic change) has not yet been well studied. The work herein explores this intersection, with consideration of a long-term discharge response (1964-2007) for a similar to 650-km(2) headwater basin of the Mara River in west Kenya, starting with stream rating and daily gauge height data. A rating model was calibrated using Bayesian methods to quantify uncertainty intervals in model parameters and predictions. There was an unknown balance of random and systemic error in rating data scatter (a scenario not likely unique to this basin), which led to an unknown balance of noise and information in the calibrated statistical error model. This had implications on testing for hydrological change. Overall, indications were that shifts in basin's discharge response were rather subtle over the 44-year period. A null hypothesis for change using flow duration curves (FDCs) from four different 8-year data intervals could be either accepted or rejected over much of the net flow domain depending on different applications of the statistical error model (each with precedence in the literature). The only unambiguous indication of change in FDC comparisons appeared to be a reduction in lowest baseflow in recent years (flows with >98% exceedance probability). We defined a subjective uncertainty interval based on an intermediate balance of random and systematic error in the rating model that suggested a possibility of more prevalent impacts. These results have relevance to management in the Mara basin and to future studies that might establish linkages to historic land use and climatic factors. The concern about uncertain uncertainty intervals (uncertainty(2)) extends beyond the Mara and is relevant to testing change where non-random rating errors may be important and subtle responses are investigated. Copyright (c) 2013 John Wiley & Sons, Ltd.

  • 161. Kalantari, Zahra
    et al.
    Santos Ferreira, Carla Sofia
    Page, Jessica
    Goldenberg, Romain
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Destouni, Georgia
    Meeting sustainable development challenges in growing cities: Coupled social-ecological systems modeling of land use and water changes2019In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 245, p. 471-480Article in journal (Refereed)
  • 162.
    Karlsson, Bengt
    et al.
    SMHI.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Brandt, Maja
    SMHI, Core Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    PULS-modellen: Struktur och tillämpningar1987Report (Other academic)
    Abstract [sv]

    1982 inleddes ett forskningsprojekt vid SMBI, som syftar till modellering av hydrokemiska förhållanden i ett vattendrag. Huvudvikten lades vid de naturliga flödesbetingade kortvariga variationerna i alkalinitet och pH. Utgångspunkten i arbetet var HBV-modellen (Bergström, 1976) samt dess vidareutveckling för grundvattensimulering (Bergström och Sandberg, 1983).Under de följande åren utvecklades den modell, som fått namnet PULS. Namnet kommer av att varje puls av regn eller snösmältning kan följas individuellt vid transporten genom marken. Filosofin bakom modellen och dess funktion finns beskriven av Bergström m fl (1985). Avsikten med denna rapport är att ge en fördjupad inblick i PULS-modellen och dess tillämpningar.Modellen har hittills tillämpats för simulering av pH och alkalinitet i 14 områden, varav 12 i Sverige och 2 i Finland.Denna rapport omfattar dels en beskrivning av modellen, dels exempel på tillämpningar i ovan nämnda områden. Eftersom tillämpningarna sträcker sig över flera år, har för de äldsta fallen ej exakt samma modellstruktur som den här beskrivna använts. Avslutningsvis visas exempel på hur man ur simulering av långa serier preliminärt kan bedöma eventuella försurningstrender.

  • 163. Kayhko, Jukka
    et al.
    Apsite, Elga
    Bolek, Anna
    Filatov, Nikolai
    Kondratyev, Sergey
    Korhonen, Johanna
    Kriauciuniene, Jurate
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Nazarova, Larisa
    Pyrh, Anna
    Sztobryn, Marzenna
    Recent Change-River Run-off and Ice Cover2015Chapter in book (Other academic)
    Abstract [en]

    This chapter compiles and assesses information on run-off and discharge from rivers within the Baltic Sea drainage basin. Some information is also available on ice duration on inland waterways. Although decadal and regional variability is large, no significant long-term change has been detected in total river run-off to the Baltic Sea over the past 500 years. A change in the timing of the spring flood has been observed due to changes in the timing of snowmelt. Change in temperature seems to explain change in run-off better than does precipitation. Later start dates for ice formation on waterways, and earlier ice break-up dates have resulted in shorter periods of ice cover.

  • 164. Khalili, Maria I.
    et al.
    Temnerud, Johan
    SMHI, Research Department, Hydrology.
    Froberg, Mats
    Karltun, Erik
    Weyhenmeyer, Gesa A.
    Nitrogen and carbon interactions between boreal soils and lakes2010In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 24, article id GB4011Article in journal (Refereed)
    Abstract [en]

    In this study, we used a large data set on nitrogen (N) and carbon (C) from Swedish boreal soils and lake waters to investigate N and C interactions between soils and lake waters. To link thousands of soils sites with hundreds of lake sites distributed all over Sweden, we gridded the data and found a significant relation between gridded C:N ratios of the organic soil layer and the ones of lake waters. We also found evidence of N deposition having depressed the C:N ratios of lake waters more than the ones of organic soil layers. In lake waters N strongly increased toward southern Sweden, mainly in the form of nitrate-nitrogen (NO(3)(-)-N) which we primarily attribute to an increased NO(3)(-)-N input from the boreal soils into the lakes. In contrast to N we found a much weaker direct relationship for C between soils and lake waters over Sweden. Instead, lake C was strongly related to lake morphometry and catchment characteristics. Our results indicate that large-scale variations in soil C content are not directly linked to C concentrations in lake waters, whereas soil N seems to leach in small amounts from the soils directly into the lakes in form of NO(3)(-)-N. Such differences in N and C interactions between soils and lake waters give important insights into the global biogeochemical cycling of N and C.

  • 165.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Berg, Peter
    SMHI, Research Department, Hydrology.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Arctic climate change in an ensemble of regional CORDEX simulations2015In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 34, article id 24603Article in journal (Refereed)
    Abstract [en]

    Fifth phase Climate Model Intercomparison Project historical and scenario simulations from four global climate models (GCMs) using the Representative Concentration Pathways greenhouse gas concentration trajectories RCP4.5 and RCP8.5 are downscaled over the Arctic with the regional Rossby Centre Atmosphere model (RCA). The regional model simulations largely reflect the circulation bias patterns of the driving global models in the historical period, indicating the importance of lateral and lower boundary conditions. However, local differences occur as a reduced winter 2-m air temperature bias over the Arctic Ocean and increased cold biases over land areas in RCA. The projected changes are dominated by a strong warming in the Arctic, exceeding 15 degrees K in autumn and winter over the Arctic Ocean in RCP8.5, strongly increased precipitation and reduced sea-level pressure. Near-surface temperature and precipitation are linearly related in the Arctic. The wintertime inversion strength is reduced, leading to a less stable stratification of the Arctic atmosphere. The diurnal temperature range is reduced in all seasons. The large-scale change patterns are dominated by the surface and lateral boundary conditions so future response is similar in RCA and the driving global models. However, the warming over the Arctic Ocean is smaller in RCA; the warming over land is larger in winter and spring but smaller in summer. The future response of winter cloud cover is opposite in RCA and the GCMs. Precipitation changes in RCA are much larger during summer than in the global models and more small-scale change patterns occur.

  • 166. Kotlarski, Sven
    et al.
    Szabo, Peter
    Herrera, Sixto
    Raty, Olle
    Keuler, Klaus
    Soares, Pedro M.
    Cardoso, Rita M.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Page, Christian
    Boberg, Fredrik
    Gutierrez, Jose M.
    Isotta, Francesco A.
    Jaczewski, Adam
    Kreienkamp, Frank
    Liniger, Mark A.
    Lussana, Cristian
    Pianko-Kluczynska, Krystyna
    Observational uncertainty and regional climate model evaluation: A pan-European perspective2019In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 39, no 9, p. 3730-3749Article in journal (Refereed)
  • 167. Krysanova, Valentina
    et al.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Gelfan, Alexander
    Gerten, Dieter
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Hattermann, Fred
    Kundzewicz, Zbigniew W.
    How the performance of hydrological models relates to credibility of projections under climate change2018In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 63, no 5, p. 696-720Article in journal (Refereed)
  • 168. Krysanova, Valentina
    et al.
    Vetter, Tobias
    Eisner, Stephanie
    Huang, Shaochun
    Pechlivanidis, Ilias
    SMHI, Research Department, Hydrology.
    Strauch, Michael
    Gelfan, Alexander
    Kumar, Rohini
    Aich, Valentin
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Chamorro, Alejandro
    van Griensven, Ann
    Kundu, Dipangkar
    Lobanova, Anastasia
    Mishra, Vimal
    Plotner, Stefan
    Reinhardt, Julia
    Seidou, Ousmane
    Wang, Xiaoyan
    Wortmann, Michel
    Zeng, Xiaofan
    Hattermann, Fred F.
    Intercomparison of regional-scale hydrological models and climate change impacts projected for 12 large river basins worldwide-a synthesis2017In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 12, no 10, article id 105002Article in journal (Refereed)
  • 169.
    Kuentz, Anna
    et al.
    SMHI, Core Services.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Hundecha, Yeshewatesfa
    SMHI, Research Department, Hydrology.
    Wagener, Thorsten
    Understanding hydrologic variability across Europe through catchment classification2017In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 21, no 6, p. 2863-2879Article in journal (Refereed)
  • 170. Larson, M.
    et al.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Jimenez, J. A.
    Hanson, H.
    Analytical model of beach erosion and overwash during storms2009In: Proceedings of the Institution of Civil Engineers: Maritime Engineering, ISSN 1741-7597, E-ISSN 1751-7737, Vol. 162, no 3, p. 115-125Article in journal (Refereed)
    Abstract [en]

    During severe storms high waves and water levels may greatly impact the sub-aerial portion of the beach inducing significant morphological change at elevations that the waves can not reach under normal conditions. Morphological formations such as dunes and barrier islands may suffer from direct wave impact and erode. Overwash occurs if the wave run-up and/or the mean water level are sufficiently high allowing for water and sediment to pass over the beach crest, which in turn causes flooding and deposition of sediment shoreward of the crest. An analytical model of sub-aerial beach response to storms was developed based on impact theory, including overwash, and the evolution of schematised dunes was investigated. Furthermore, the analytical model was applied to the case of schematised barrier islands exposed to extensive overwash. After validation using field data, the analytical model was employed at two coastal sites, namely Ocean City on the United States east coast and the Ebro Delta on the Spanish Mediterranean coast, in order to calculate quantities for assessing the storm impact on beaches, such as eroded volume, overwash volume, beach crest reduction, and contour-line retreat. These quantities were subsequently analysed to derive empirical probability distribution functions to be utilised in different types of risk assessment concerning flooding and erosion in coastal areas.

  • 171.
    Larsson, Sara
    et al.
    SMHI.
    Lidén, Rikard
    SMHI, Research Department, Hydrology.
    Stationstäthet och hydrologiska prognoser1996Report (Other academic)
    Abstract [en]

    Ten basins in the north of Sweden, where the hydrological model system, HBV- HMS, has been set up, were studied. The effects on the hydrological model if an approximate 20% decrease in meteorological stations occurs were studied as well as the possibility to reduce an eventual decline in model efficiency through recalibration of the model parameters. Also, an addition of stations was investigated. The results indicated that the mean reduction in model efficiency due to an approximate 20% decrease in station density was small. If the most representative stations were removed the model performance, however, decreased significantly. When a recalibration was allowed the decline in model accuracy was reduced considerably. An addition of meteorological stations gave a minor improvement in model efficiency. No significant relationships between the basin characteristics and the model sensitivity due to a change in the station network, were found.

  • 172.
    Lidén, Rikard
    SMHI, Research Department, Hydrology.
    A new approach for estimating suspended sediment yield1999In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 3, no 2, p. 285-294Article in journal (Refereed)
    Abstract [en]

    A semi-distributed conceptual model, HBV-SED, for estimation of total suspended sediment concentration and yield at the outlet of a catchment was developed and tested through a case study. The base of the suspended sediment model is a dynamic hydrological model, which produces daily series of areal runoff and rainfall for each sub-basin as input to the sediment routine. A lumped measure of available sediment is accumulated continuously based on a linear relationship between log-transformed values of rainfall and erosion, while discharge of suspended sediment at the sub-basin outlet is dependent on runoff and amount of stored available sediment. Four model parameters are empirically determined through calibration against observed records of suspended sediment concentration. The model was applied to a 200 km(2) catchment with high altitude differences in the tropical parts of Bolivia, where recorded suspended sediment concentrations were available during a two-year period. 10,000 parameter sets were generated through a Monte Carlo procedure to evaluate the parameter sensitivity and interdependence. The predictability of the model was assessed through dividing the data record into a calibration and an independent period for which the model was validated and compared to the sediment rating curve technique. The results showed that the slope coefficients of the log-transformed model equations for accumulation and release were much stronger than the intercept coefficients. Despite an existing interdependence between the model parameters, the HBV-SED model gave clearly better results than the sediment rating curve technique for the validation period, indicating that the supply-based approach has a promising future as a tool for basic engineering applications.

  • 173.
    Lidén, Rikard
    et al.
    SMHI, Research Department, Hydrology.
    Harlin, Joakim
    SMHI.
    Analysis of conceptual rainfall-runoff modelling performance in different climates2000In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 238, no 3-4, p. 231-247Article in journal (Refereed)
    Abstract [en]

    With the objective of studying conceptual rainfall-runoff modelling performance in different climates, the HBV-96 model was applied on four catchments located in Europe, Africa and South America. Manual, automatic and Monte Carlo techniques were used for model calibration and parameter analyses. It was found that the magnitude of the water balance components had a significant influence on model performance. Performance decreased and demands of calibration period length increased with increased catchment dryness primarily because of a neater water balance and higher climatic variability in drier areas. A large degree of equifinality was discovered in all catchments where different calibration methods yielded equally good results but with different parameter combinations. Thus, it may be impossible to know if an optimum parameter set exists and to relate parameter values to physical properties of the catchment. On the other hand the validation results indicated that it might not matter if parameter values were not unique when studying runoff solely, provided the model application is within the same regime of flows. (C) 2000 Elsevier Science B.V. AU rights reserved.

  • 174.
    Lidén, Rikard
    et al.
    SMHI, Research Department, Hydrology.
    Vasilyev, A
    Stalnacke, P
    Loigu, E
    Wittgren, Hans Bertil
    SMHI, Research Department.
    Nitrogen source apportionment - a comparison between a dynamic and a statistical model1999In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 114, no 2-3, p. 235-250Article in journal (Refereed)
    Abstract [en]

    A dynamic model, HBV-N, and a statistical model, MESAW, for nitrogen source apportionment were compared regarding model performance, model uncertainty and user applicability. The HBV-N model simulates continuous series of nitrogen concentrations with meteorological data and sub-basin characteristics as input. Diffuse nitrogen emissions are defined as regional model parameters which are calibrated by comparison of observed and simulated nitrogen data. The MESAW model uses nitrogen loads for a fixed time interval at each monitoring site as response variable and sub-basin characteristics as explanatory variables to estimate diffuse nitrogen emissions through non-linear regression analysis. The two models were applied in the Matsalu Bay watershed (3640 km(2)) in Estonia and the same land use and point sources data were used as input. Both models gave similar levels of diffuse total nitrogen emissions and retention rates, which also fit well with previous estimates made in Estonia and Scandinavia. A sensitivity analysis of the model parameters also showed similar uncertainty levels, which indicated that the model uncertainty was more dependent on the availability of nitrogen data and land cover distribution than the choice of model. Furthermore, the sensitivity analysis showed a parameter interdependency in both models, which implied the risk of compensation between estimated diffuse emissions and retention. In conclusion, however, the study showed that both models were capable of estimating nitrogen leakage from the dominating land classes and giving reliable source apportionment from the available input data. The study indicated that the HBV-N model has its advantage in assessments where detailed outputs are needed and when run-off data are limited, while the statistical MESAW model has its advantage in extensive studies since it is easily applied to large watersheds that have dense monitoring networks. (C) 1999 Elsevier Science B.V. All rights reserved.

  • 175.
    Lindell, Sten
    et al.
    SMHI, Professional Services.
    Carlsson, Bengt
    SMHI, Research Department, Hydrology.
    Sanner, Håkan
    SMHI, Core Services.
    Reihan, Alvina
    SMHI.
    Vedom, Rimma
    Application of the integrated hydrological modelling system IHMS-HBV to pilot basin in Estonia1996Report (Other academic)
    Abstract [en]

    This report describes calibration and application of the IHMS-HBV model on a daily time step to Kasari River basin in Estonia. The Swedish Meteorological and Hydrological Institute (SMHI) have as consultant been responsible for the set-up, calibration, training and delivery of the Integrated Hydrological Model System with the HBV-model (IHMSHBV). The Swedish Board for lnvestment and Technical Support (BITS) financed the project. The training and transfer of technology were addressed to the Estonian Meteorological and Hydrological Institute (EMHI).

  • 176.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    A simple automatic calibration routine for the HBV model1997In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 28, no 3, p. 153-168Article in journal (Refereed)
    Abstract [en]

    A simple, but efficient, method for automatic calibration of the conceptual HBV rainfall-runoff model was developed. A new criterion, which combines the commonly used efficiency criterion R-2 and the relative volume error was introduced. 2 values nearly as high as those Optimising this combined criterion resulted in R-2 for optimising only R-2, but With much smaller volume errors. An earlier automatic calibration method for the HBV model relied on the use of different criteria for different parameters. With the simplification to one single criterion, the optimum search method could be made more efficient. The optimisation is made for one parameter at a time, while the others are kept constant. This one-dimensional optimisation is repeated in a loop for all parameters. A new loop is performed as long as there is a sufficiently large improvement since the last one. After each loop a search is made in the direction which is defined by the differences in parameter values between the two latest loops. The calibration routine was developed for, and tested with, the HBV model, but it should be general enough to be applicable to other models as well.

  • 177.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Analys av avrinningsserier för uppskattning av effektivt regn1987Report (Other academic)
    Abstract [sv]

    En metod för beräkning av effektiv nederbörd ur avrinningsserier presenteras. Metoden innebär, att hela avrinningsområdet betraktas som en effektiv regnmätare, vilken analyseras via sin avrinningsserie. Resultaten inkluderar bidrag från regn, snösmältning och förluster pga magasinering i marken samt tar hänsyn till den areella variationen i alla dessa faktorer.Den föreslagna metoden har tillämpats på 31 avrinningsserier, företrädesvis från områden i norra Sverige, totalt omfattande1 365 observationsår. De erhållna uppskattningarna av effektiva regn är för nederbördstillfällen med enbart regn i allmänhet avsevärt lägre än den nederbördsmängd, som fallit över området. Dessutom kan i flera områden en viss reduktion av risken för höga effektiva regn sommartid skönjas. Orsaken till detta är i första hand effekten av ett markfuktighetsunderskott sommartid. I utpräglade fjällområden är detta förhållande ej lika framträdande.En viss minskning av den största påträffade effektiva regnmängden med ökande areal framgår av materialet.Stora effektiva regn, orsakade av snösmältning under våren, är mer frekventa än stora regntillfällen under sommar och höst, i synnerhet om flerdygnsvärden analyseras.

  • 178.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Floods in Sweden – Trends and occurrence1993Report (Other academic)
    Abstract [en]

    Sweden experienced a number of large floods in the 1980-ies. This raised the question of whether floods were becoming more frequent. A systematic study on floods was carried out, to provide a perspective to past and future floods. Frequency analysis was made using 16 methods. A split-sample test was used for evaluation of the predictive power of the methods. Numerical criteria were used for measuring the goodness of fit. The return periods of observed floods were estirnated by use of plotting positions.

    No convincing evidence of trends was found. The 1980-ies had larger floods than usual, where as the 1970-ies had few high floods, especially, in the auturnn. This may have led to the, irnpression of a trend. No evidence of autocorrelation or periodicity was found. For most of Sweden, the spring was found to be the season with highest extremes. The flood-moderating effect of regulation was illustrated, although floods were also found to occur in regulated systems. The results from the frequency analysis depended on the choice of criteria. In general, however, distributions with two parameters performed best. Neither a two component model treating spring and autumn separately, three parameter distributions, nor regional analyses gave any irnprovements. The spatial correlation within the data was considerable.

  • 179.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Lake water levels for calibration of the S-HYPE model2016In: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 47, no 4, p. 672-682Article in journal (Refereed)
  • 180.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Regional kalibrering av HBV-modellen2006Report (Other academic)
    Abstract [sv]

    HBV-modellen, som används av den hydrologiska varningstjänsten vid SMHI, är en förenklad beskrivning av det hydrologiska kretsloppet. En befintlig metod för regional kalibrering av HBVmodellen vidareutvecklades. Parametrar tas fram som ger så god överensstämmelse som möjligt till flera vattenföringsstationer i en region. Dessa värden kan därefter användas för uppskattning av vattenföringen i en godtycklig punkt i regionen. Metoden testades i tre områden: Rönne å i Skåne, Dillområdet i Tyskland och den region som omfattar vattendragen till Västerhavet. Regionala utvidgningar av R2-värdet, volymfel och toppfel kombineras i ett optimeringskriterium. R2-värdet och toppfelet bör utvärderas endast i små, oreglerade områden med låg sjöprocent. Som övre gränser sattes en areal på 2000 km2 och en sjöprocent på 10 %. Det sistnämnda visade sig dock vara för högt satt.Volymfelet kan däremot utvärderas i samtliga ingående stationer, och få påverka kalibreringen. I de relativt små, homogena områdena Rönne å och Dill erhölls mycket goda resultat. Anpassningen blev något sämre med regionala parametrar än vad som kan uppnås genom lokal kalibrering i det stora testområdet, vattendragen till Västerhavet. I allmänhet underskattades toppflödena något. Fördelen är att man får parametervärden som användas i hela regionen.

  • 181.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Vattentillgång och höga flöden i Sverige under 1900-talet2002Report (Other academic)
    Abstract [en]

    Water resources and floods in Sweden were studied with respect to trends and occurrence, with emphasis on the period 1901-2000. Two periods stand out when it comes to annual runoff: the 1920s, and the two last decades in the study period, with a runoff anomaly compared to the whole century of about +8%. The 1970s was the driest decade, with a runoff about 9 % below the century average. The most deviating 30-year period was 1951-80 with an anomaly of -5 % compared to 1901-2000. The few records that are available from the 19th century indicate an even higher runoff, but at lower temperatures. A linear regression to the runoff <luring the whole 20 th century gives an increase of 4 %, but the change was not statistically significant. The analysis of flood peaks suffers from uncertainties in the data. Flood peaks in old data were probably underestimated, since readings were made less frequently than today. A linear regression to annual flood peaks <luring the period 1911-2000 indicates an increase with about 10 %. This increase is almost significant at the 95 % level. The clearest increase was, however, found in basins with the less reliable observations. A smaller increase was obtained for an alternative selection of stations, which were considered to be more reliable. No significant trend was found in the selection of more reliable data. Seen in a shorter perspective, the autumn floods increased considerably <luring the period 1970-2000. Similar autumn floods, were, however; experienced in the 1920s. No increased frequency of very high floods, with a retum period of at least 10 years, could be determined.

  • 182.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Alexandersson, Hans
    SMHI.
    Recent mild and wet years in relation to long observation records and future climate change in Sweden2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, no 4-5, p. 183-186Article in journal (Refereed)
    Abstract [en]

    Recent mild and wet years in Sweden were compared with long observation series of temperature, precipitation and runoff. Spatial average series for northern and southern Sweden were constructed and analyzed for the period 1901-2002. Precipitation increased considerably during the period, whereas temperature and runoff increases were weaker. On average, for the whole country, the differences between the period 1991-2002 and 1901-1990 were +0.7degreesC for temperature, +11% in precipitation and +7% in runoff. The differences in temperature and precipitation, but not runoff, were significant at the 5% level. However, the 1930s were equally mild, and the runoff was almost as high in the 1920s. The characteristic feature of the past decade is the combination of high temperature, precipitation and runoff. The deviation between the most recent decade and the preceding years is consistent with climate scenario projections for Sweden, but there are also differences in the seasonal pattern.

  • 183.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Bartosova, Alena
    SMHI, Research Department, Hydrology.
    Hjerdt, Niclas
    SMHI, Core Services.
    Strömqvist, Johan
    SMHI, Research Department, Hydrology.
    Uppehållstider i ytvatten i relation tillvattenkvalitetNET, ett generellt uppskalningsverktyg2018Report (Other academic)
    Abstract [sv]

    NET är ett verktyg för uppskattning av vattenburen transport av olika ämnen i punkter där detsaknas mätningar. Verktyget togs ursprungligen fram inom forskningsprogrammet ”Climatechange and the Environmental Objectives” (CLEO, Munthe et al., 2014 och 2016). Tanken äratt NET ska vara generellt, och kunna användas för simulering av olika ämnen, men endastberäkna medelvärden över tiden av mängder och koncentrationer. Ofta är det mängder som ärslutmålet för en beräkning, varför det i vissa situationer kan finnas mycket att vinna på attanvända en enkel och snabb beräkningsmodell. Inom CLEO simulerades flöden av totalkväve,total-fosfor och totalt organiskt kol.

  • 184.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Runoff trends in Sweden 1807-20022004In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 49, no 1, p. 69-83Article in journal (Refereed)
    Abstract [en]

    Time series of annual runoff volumes and annual and seasonal flood peaks in Sweden were analysed. The study included a total of 61 discharge series, with emphasis on the period 1901-2002. Three wet decades stand out in the 20th century: the 1920s, 1980s and 1990s, with a runoff anomaly of +8%. The 1970s were very dry. In a short perspective, both runoff volumes and flood magnitude increased substantially between 1970 and 2002, but similar conditions were experienced in the 1920s. The linear regression line for the average runoff from all of Sweden increased by 5% over the past century, but the trend was not statistically significant. The runoff in the 19th century was in fact even higher than in recent decades, although temperatures were lower. Flood levels increased slightly more than annual runoff volumes in northern Sweden. However, flood peaks in old data are probably underestimated. The largest increase was consequently found in less reliable data series. It is therefore difficult to conclude that flood levels are actually increasing.

  • 185.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Bishop, K
    Lofvenius, M O
    Soil frost and runoff at Svartberget, northern Sweden - measurements and model analysis2002In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 16, no 17, p. 3379-3392Article in journal (Refereed)
    Abstract [en]

    The effect of soil frost on runoff was investigated using a comprehensive data set collected at the Svartberget Experimental Forest, near Vindeln, Vasterbotten in northern Sweden. Measurements of snow depth, soil temperature, frost depth and other climate parameters have been made at three sites since 1981, as part of a long-term climate monitoring programme. Simulation residuals from the HBV rainfall-runoff model, in which no effect of soil frost is assumed, were compared with 16 years of measured soil frost conditions. A simple model for simulation of soil frost depth was developed and incorporated into the HBV model. The model parameters were calibrated to observations of snow depth, soil frost depth, groundwater levels and runoff, by use of a simple weighted optimization criterion. No clear effect of soil frost could be seen on the timing and magnitude of runoff in this analysis, or when analysing data on the conservative oxygen isotope O-18. The soil at the forested site froze in only slightly more than half the years, despite the high latitude and low winter temperatures. Furthermore, the soil had often thawed before the start of the spring flood. Almost all spring floods, therefore, occurred when the soil was unfrozen. Snow depth and soil frost depths were inversely related, with the deepest soil frost during winters with little snow. Soil frost therefore is unlikely to aggravate the very high floods in forested basins of this type, except perhaps under exceptional circumstances such as large rain events on frozen ground. Copyright (C) 2002 John Wiley Sons, Ltd.

  • 186.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Johansson, Barbro
    SMHI, Professional Services.
    Persson, Magnus
    SMHI.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    HBV-96 – En areellt fördelad modell för vattenkrafthydrologin1996Report (Other academic)
  • 187.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Persson, Magnus
    SMHI.
    Conceptual modelling of evapotranspiration for simulations of climate change effects1994Report (Other academic)
    Abstract [en]

    The evapotranspiration routines in existing conceptual hydrological models have been identified as one of the weaknesses which appear when these rnodels are used for the simulation of hydrological effects of a changing clirnate. The hydrological models in operational use today usually have a very superficial description of evapotranspiration. They have, nevertheless, been able to yield reasonable results. The objective of this paper is to analyse and suggest modifications of existing evapotranspiration routines in conceptual hydrological models to make them more appropriate for use in simulation of the effects of a changing climate on water resources.

    The following rnodifications of the evapotranspiration routine were formulated and tested in the HBV model: Ternperature anomaly correction of evapotranspiration, potential evapotranspiration by a simplified Thornthwaite type formula, interception submodel, spatially distributed evapotranspiration routine and alternative forrnulations of lake evapotranspiration. Sensitivity analyses were thereafter rnade to illustrate the effects of uncertainty in the hydrological model structure versus those of the uncertainty in the climate change predictions.

  • 188.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Harlin, Joakim
    SMHI.
    SPILLWAY DESIGN FLOODS IN SWEDEN .2. APPLICATIONS AND SENSITIVITY ANALYSIS1992In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 37, no 5, p. 521-539Article in journal (Refereed)
    Abstract [en]

    The recently developed guidelines for design flood calculation in Sweden are based on simulation with a hydrological model. Several meteorological and hydrological conditions are prescribed as input to the model. The sensitivity of the floods according to the new guidelines with respect to those prescriptions is checked as well as the sensitivity to the modelling procedure. In this paper, the HBV hydrological model is used. It is shown that the most sensitive input factor is the design 14-day precipitation sequence. For autumn floods, the scaling relation between the precipitation sequence and the generated floods is in the order of 1:1. For spring floods on the other hand, snowmelt influences the flood magnitude and reduces the sensitivity to precipitation to about 1:0.6. Soil moisture modelling was important in basins with high evapotranspiration. Model calibration could have a large effect on the design flood magnitude. The most sensitive parameter was the high flow recession coefficient, K0. The water stage development in a multi-reservoir system is further influenced by the regulation strategy and spillway capacity. An increased spillway capacity can improve the situation considerably for a particular dam but could at the same time worsen the situation for downstream dams. After the filling of the reservoir there was a clear relation between inflow peak and maximum water stage. The study shows that it is difficult to assess the integrated effects of extreme precipitation, snowmelt, soil moisture status and regulation in a system beforehand.

  • 189.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Harlin, Joakim
    SMHI.
    Olofsson, Judith
    SMHI, Core Services.
    Uppföljning av Flödeskommitténs riktlinjer1993Report (Other academic)
    Abstract [sv]

    Flödeskommittens förslag till nya riktlinjer för bestämning av dimensionerande flöden för dammanläggningar utkom 1990. Kontrollberäkningar enligt riktlinjerna visar att de dimensionerande flödena för hösten ligger något lägre än de preliminära beräkningarna i Flödeskommittens rapport. Medelvärdet av de uppmätta flödena i relation till de dimensionerande är med det nu tillgängliga materialet 43% för våren och 40% för hösten. Det finns inga tydliga skillnader i säkerhetsmarginal mellan olika delar av landet, eller mellan vår och höst. Trots detta finns det en relativt stor spridning mellan stationerna.Samtidigheten mellan hög snösmältning och hög nederbörd studerades. Resultaten visar att de två faktorerna sällan uppträder samtidigt. Genom att man i en dimensioneringsberäkning kombinerar kraftig snösmältning och extrem nederbörd fås en avsevärd säkerhetsmarginal, trots att ingen av de två faktorerna har extrapolerats utanför det observerade. De högsta flödena i oreglerade vattendrag i Norrland skapas i första hand av snösmältning. En mindre del av flödena är kombinationsflöden, och en ännu mindre andel domineras av regn. Höstflödena, som vanligtvis är lägre, domineras dock av regn. I södra Sverige orsakas de högsta flödena ofta av kombinationer av regn och snösmältning.Det är mycket svårt att fastställa återkomsttiden för de dimensionerande flödena med någon större precision. Man kan inte förutsätta att de dimensionerande flödena har samma återkomsttid överallt. Det mesta talar dock för att återkomsttiden överstiger 10 000 år med god marginal i de flesta områdena. Risken för att ett dimensionerande flöde skall uppträda någonstans i landet under en hundraårsperiod, bör vara mycket liten. Säkerhetsmarginalen, eller återkomsttiden, tycks ligga på ungefär samma nivå för våren som för hösten. Det är mycket svårt att uppskatta de dimensionerande flödenas återkomsttid genom att utgå från återkomsttiden för det dimensionerande regnet på 24 timmar. Detta beror på att regnets återkomsttid ej är känd och att de högsta flödena i landet till största delen orsakas av snösmältning eller långvarigt regn.Ett något mer homogent resultat vad beträffar det 30 åriga snötäcket i en dimensioncringsberäkning erhölls då snötäckena uppdaterades med hjälp av den uppmätta vattenföringsserien. Underlaget är dock ganska begränsat. Den justering av 30-årssnön som erhölls i de 2 testade områdena innebar en justering av tillrinningsmaximum med knappt 2%. En ny förbättrad avdunstningsrutin i HBV-modellen, hade obetydlig effekt på de  dimensionerande flödena på våren. De dimensionerande höstflödena i södra samt östra Sverige blev I0 - 22 % högre med den nya avdunstningsfunktionen.De höga flödena under sommaren 1993 var i flera av de reglerade Norrlandsälvarna exceptionellt höga för årstiden, men däremot inte i förhållande till oreglerade vårflöden. Exempelvis skulle sommarens flödesnivå i Luleälven uppnås ungefär vart femte år om älven hade varit oreglerad. Nederbördsmängdema på ett dygn låg långt under Flödeskommittens dimensionerande värden. Tillrinningstoppen till Parki och Letsi i Luleälvenanalyserades närmare. Långvarigt regn, och inte snösmältning, var den utlösande faktorn för flödestoppen.

  • 190.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Johansson, Barbro
    SMHI, Professional Services.
    Persson, Magnus
    SMHI.
    Gardelin, Marie
    SMHI, Professional Services.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Development and test of the distributed HBV-96 hydrological model1997In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 201, no 1-4, p. 272-288Article in journal (Refereed)
    Abstract [en]

    A comprehensive re-evaluation of the HBV hydrological model has been carried out. The objectives were to improve its potential for making use of spatially distributed data, to make it more physically sound and to improve the model performance. The new version, HBV-96, uses subbasin division with a typical resolution of 40 km(2), although any resolution can be used. In addition, each subbasin is divided into elevation bands, vegetation and snow classes. Automatic weighting of precipitation and temperature stations was introduced and a new automatic calibration scheme was developed. The modifications led to significant improvements in model performance. In seven test basins the average value of the efficiency criterion R-2 increased from 86 to 89%, with improvements in both the calibration and verification periods. (C) 1997 Elsevier Science B.V.

  • 191.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Ottosson Löfvenius, Mikael
    Vindelns försöksparker SLU.
    Tjäle och avrinning i Svartberget - studier med HBV-modellen2000Report (Other academic)
    Abstract [sv]

    Det finns åtskilliga studier som tyder på att avrinningen från öppen mark, särskilt jordbruksmark,

    påverkas av tjäle. För skogsmark är förhållandena mindre undersökta. Tjälens

    inverkan på avrinningen undersöktes mha ett mycket fint datamaterial insamlat vid Svartbergets

    försökspark nära Vindeln i Västerbotten. Bland annat har snödjup, marktemperatur

    och tjäldjup mätts sedan 1980, vid tre platser. En av mätplatsema är belägen i gammal

    granskog och de två andra på öppen mark. Dessutom fanns grundvattendata att tillgå från

    området.

    Simuleringsresultat från HBV-modellen, i vilken ingen effekt av tjälen antas, jämfördes med

    uppmätta tjälförhållanden i skogen. Ingen tydlig effekt av tjälen kunde urskiljas, på detta sätt

    eller genom analys av mätningar med den konservativa syreisotopen

    180. Marken under

    skogen tjälas endast ungefär vartannat år. Under flera vintrar tinade tjälen dessutom upp innan

    vårfloden kom igång. Nästan alla vårflödena inträffade då marken var otjälad. Tjälens

    eventuella inverkan har mindre betydelse eftersom det så få vintrar finns kvar tjäle när

    vårfloden kulminerar. Vintrar med djup tjäle är ofta ganska snöfattiga och resulterar i låga

    flöden. Om dessa måttliga flöden påverkas eller ej har liten betydelse för uppkomsten av

    översvämningar. Slutsatserna gäller i första hand för gammal granskog i Svartberget. De två

    öppet belägna mätplatsema uppvisar mycket djupare och mer långvarig tjäle.

    En enkel modell för beräkning av snödjup och tjäldjup sattes upp. Densiteten för snön antogs

    bero av snöns medelålder. Resultaten var ganska goda. Tjäldjupet kunde beräknas någorlunda

    no

    i grant med en enkel modell som framförallt styrs av en utjämnad lufttemperatur. Genom att

    HBV-modellen kalibrerades mot både vattenföring och snödjup erhölls en möjlighet att

    uppdatera modellen mha snödj,upsmätningar

    . Modellen kunde fås att stämma ganska bra

    överens med uppmätta värden på snödjup, grundvatten, tjäldjup och vattenföring samtidigt,

    efter samtidig kalibrering mot dessa variabler.

  • 192.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Pers, Charlotta
    SMHI, Research Department, Hydrology.
    Rosberg, Jörgen
    SMHI, Research Department, Hydrology.
    Strömqvist, Johan
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Development and testing of the HYPE (Hydrological Predictions for the Environment) water quality model for different spatial scales2010In: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 41, no 3-4, p. 295-319Article in journal (Refereed)
    Abstract [en]

    The HYPE model is a hydrological model for small-scale and large-scale assessments of water resources and water quality, developed at the Swedish Meteorological and Hydrological Institute during 2005-2007. In the model, the landscape is divided into classes according to soil type, land use and altitude. In agricultural lands the soil is divided into three layers, each with individual computations of soil wetness and nutrient processes. The model simulates water flow and transport and turnover of nitrogen and phosphorus. Nutrients follow the same pathways as water in the model: surface runoff, macropore flow, tile drainage and outflow from individual soil layers. Rivers and lakes are described separately with routines for turnover of nutrients in each environment. Model parameters are global, or coupled to soil type or land use. The model was evaluated both by local calibrations to internal variables from different test basins and to data on discharge and nutrients from a large number of small basins. In addition, the estimated parameters were transferred to two larger basins in southern Sweden: River Ronnea and River Vindan. The resulting simulations were generally in good agreement with observations.

  • 193.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    RODHE, A
    MODELING WATER EXCHANGE AND TRANSIT TIMES IN TILL BASINS USING O-181986In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 17, no 4-5, p. 325-334Article in journal (Refereed)
  • 194.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    RODHE, A
    TRANSIT TIMES OF WATER IN SOIL LYSIMETERS FROM MODELING OF O-181992In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 65, no 1-2, p. 83-100Article in journal (Refereed)
    Abstract [en]

    A proper description of water pathways and transit times is important in the simulation of groundwater acidification using hydrochemical models. A simple water balance model, describing water flow and transit times in different soil layers, was developed and tested by the use of the stable isotope O-18 as a natural tracer in soil lysimeters. Drainage was collected from lysimeters of three depths: 15, 40, and 80 cm, from two sites in the Stubbetorp research basin in south-eastern Sweden. The content of O-18 in the precipitation and in the drainage from the lysimeters was measured during 2 yr. O-18 was regarded as an ideal tracer, and its concentration in the drainage was modeled using the concentration in the precipitation as input. The percolation from each soil layer was assumed to depend on the inflow and the soil moisture storage in the layer. The most important model parameter, the field capacity, was derived from field information. Sensitivity analysis showed that the model was rather insensitive to other parameter values. Although simple, the model gave good results, both for the flow of water and O-18. The best results were obtained, when ideal mixing in the upper horizons of the soil was combined with piston flow at greater depths. Preferential flow was not found to be of great importance, nor was immobile water. Particle flow velocities and transit times in the soil lysimeters were simulated. The average particle flow velocities were about 0.6 cm d-1. The use of a dynamic model made it possible to simulate the temporal variations in transit times for water in the soil lysimeters. The mean transit times for the 80 cm lysimeter ranged from about 3 to 6 mo with an average value of 4 mo.

  • 195.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Rosberg, Jörgen
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Parameter precision in the HBV-NP model and impacts on nitrogen scenario simulations in the Ronnea River, Southern Sweden2005In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, no 7, p. 533-537Article in journal (Refereed)
    Abstract [en]

    The HBV-NP model is a newly developed water quality model that describes the turnover and fluxes of both nitrogen and phosphorous. It is based on the conceptual precipitation/runoff HBV model. The HBV-NP model was applied for simulation of nitrogen for the Ronnea catchment in southern Sweden. The catchment was divided into 64 subcatchments in the model. Discharge measurements from six stations and nitrogen measurements from 12 stations were used in the calibration of parameters in the model. Eight automatic calibrations were performed with different combinations of time periods, objective functions, and levels of the nitrogen load in the model. A regionally extended interpretation of the Nash-Sutcliffe R-2 criterion was used in the calibration. In the evaluation of the criterion, the errors were summed over both time steps and sampling points. Scenario simulations of combined measures for reduction of nitrogen load into the sea by 30% were thereafter performed with the eight sets of parameters established by calibration. The model parameters were not uniquely defined by the calibration. However, the simulated relative reduction of nitrogen load into the sea was relatively insensitive to the choice of parameter set, given the available input sources, variables, and data.

  • 196. Lyon, Steve W.
    et al.
    Nathanson, Marcus
    Spans, Andre
    Grabs, Thomas
    Laudon, Hjalmar
    Temnerud, Johan
    SMHI, Research Department, Hydrology.
    Bishop, Kevin H.
    Seibert, Jan
    Specific discharge variability in a boreal landscape2012In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 48, article id W08506Article in journal (Refereed)
    Abstract [en]

    Specific discharge variations within a mesoscale catchment were studied on the basis of three synoptic sampling campaigns. These were conducted during stable flow conditions within the Krycklan catchment study area in northern Sweden. During each campaign, about 80 individual locations were measured for discharge draining from catchment areas ranging between 0.12 and 67 km(2). These discharge samplings allowed for the comparison between years within a given season (September 2005 versus September 2008) and between seasons within a given year (May 2008 versus September 2008) of specific discharge across this boreal landscape. There was considerable variability in specific discharge across this landscape. The ratio of the interquartile range (IQR) defined as the difference between the 75th and 25th percentiles of the specific discharges to the median of the specific discharges ranged from 37% to 43%. Factor analysis was used to explore potential relations between landscape characteristics and the specific discharge observed for 55 of the individual locations that were measured in all three synoptic sampling campaigns. Percentage wet area (i.e., wetlands, mires, and lakes) and elevation were found to be directly related to the specific discharge during the drier September 2008 sampling while potential annual evaporation was found to be inversely related. There was less of a relationship determined during the wetter post spring flood May 2008 sampling and the late summer rewetted September 2005 sampling. These results indicate the ability of forests to "dry out" parts of the catchment over the summer months while wetlands "keep wet" other parts. To demonstrate the biogeochemical implications of such spatiotemporal variations in specific discharge, we estimate dissolved organic carbon (DOC) exports with available data for the May 2008 and September 2008 samplings using both the spatially variable observed specific discharges and the spatially constant catchment average values. The average absolute difference in DOC export for the various subcatchments between using a variable and using a constant specific discharge was 28% for the May 2008 sampling and 20% for the September 2008 sampling.

  • 197. MacDonald, Matthew K.
    et al.
    Stadnyk, Tricia A.
    Dery, Stephen J.
    Braun, Marco
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    Isberg, Kristina
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Impacts of 1.5 and 2.0 degrees C Warming on Pan-Arctic River Discharge Into the Hudson Bay Complex Through 20702018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 15, p. 7561-7570Article in journal (Refereed)
  • 198. Magnusson, Jan
    et al.
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    Huesler, Fabia
    Jonas, Tobias
    Assimilation of point SWE data into a distributed snow cover model comparing two contrasting methods2014In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 50, no 10, p. 7816-7835Article in journal (Refereed)
    Abstract [en]

    In alpine and high-latitude regions, water resource decision making often requires large-scale estimates of snow amounts and melt rates. Such estimates are available through distributed snow models which in some situations can be improved by assimilation of remote sensing observations. However, in regions with frequent cloud cover, complex topography, or large snow amounts satellite observations may feature information of limited quality. In this study, we examine whether assimilation of snow water equivalent (SWE) data from ground observations can improve model simulations in a region largely lacking reliable remote sensing observations. We combine the model output with the point data using three-dimensional sequential data assimilation methods, the ensemble Kalman filter, and statistical interpolation. The filter performance was assessed by comparing the simulation results against observed SWE and snow-covered fraction. We find that a method which assimilates fluxes (snowfall and melt rates computed from SWE) showed higher model performance than a control simulation not utilizing the filter algorithms. However, an alternative approach for updating the model results using the SWE data directly did not show a significantly higher performance than the control simulation. The results show that three-dimensional data assimilation methods can be useful for transferring information from point snow observations to the distributed snow model. Key Points <list id="wrcr21142-list-0001" list-type="bulleted"> <list-item id="wrcr21142-li-0001">Evaluating methods for assimilating snow observations into distributed models <list-item id="wrcr21142-li-0002">Assimilation can improve model skill also at locations without observations <list-item id="wrcr21142-li-0003">Assimilation of fluxes appears more successful than assimilation of states <doi origin="wiley" registered="yes">10.1002/(ISSN)1944-7973</doi

  • 199. Malnes, E.
    et al.
    Buanes, A.
    Nagler, T.
    Bippus, G.
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    Schiller, C.
    Metsamaki, S.
    Pulliainen, J.
    Luojus, K.
    Larsen, H. E.
    Solberg, R.
    Diamandi, A.
    Wiesmann, A.
    User requirements for the snow and land ice services - CryoLand2015In: The Cryosphere, ISSN 1994-0416, E-ISSN 1994-0424, Vol. 9, no 3, p. 1191-1202Article in journal (Refereed)
    Abstract [en]

    CryoLand (2011-2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sustainable services after the project is completed. The project has performed a thorough user requirement survey in order to derive targeted requirements for the service and provide recommendations for the design and priorities of the service. In this paper we describe the methods used, the major findings in this user survey, and how we used the results to design and specify the CryoLand snow and land ice service. The user requirement analysis shows that a European operational snow and land ice service is required and that there exists developed cryosphere products that can meet the specific needs. The majority of the users were mainly interested not only in the snow services, but also the lake/river ice products and the glacier products were desired.

  • 200. Mangini, Walter
    et al.
    Viglione, Alberto
    Hall, Julia
    Hundecha, Yeshewatesfa
    SMHI, Research Department, Hydrology.
    Ceola, Serena
    Montanari, Alberto
    Rogger, Magdalena
    Salinas, Jose Luis
    Borzi, Iolanda
    Parajka, Juraj
    Detection of trends in magnitude and frequency of flood peaks across Europe2018In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 63, no 4, p. 493-512Article in journal (Refereed)
1234567 151 - 200 of 332
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