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  • 181.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Södling, Johan
    SMHI, Affärsverksamhet.
    Wetterhall, Fredrik
    SMHI, Forskningsavdelningen, Hydrologi.
    Högupplösta nederbördsdata för hydrologisk modellering: en förstudie2013Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Hydrologisk modellering vid SMHI utförs normalt med tidssteget 1 dygn. Emellertid finns idag förutsättningarför både simulering och prognos på kortare tidssteg, dels genom en rumsligt högupplöst hydrologisk modell (S-HYPE), dels genom högupplösta indata. I denna förstudie har olika typer av observationsbaserade, högupplösta indata (främst nederbörd)inventerats, sammanställts och utvärderats på olika tids- och rumsskalor: automatstationsdata, PTHBV, MESAN, radardata. En ny produkt kallad PTHBV-radar har tagits fram, i vilken PTHBVs dygnsnederbörd fördelats över dygnet m.h.a. radarobservationer. De olika datatyperna testades vid hydrologisk simulering med HYPE-modellen i ett mindre avrinningsområde.För långa ackumulationstider (år, månad) ger PTHBV högre värden än MESAN. Radardata har tydliga artefakter, t.ex. i gränser mellan radarer, men regionala medelvärden överensstämmer med övriga källor. Vad gäller 1-h nederbörd är den genomsnittliga överensstämmelsen med automatstationsdata bäst för MESAN, följt av PTHBV-radar och radar. Den rumsliga utjämningen i MESAN leder dock till lägre värden på maximala nederbörds-intensiteter, i detta avseende ligger PTHBV-radar och radar närmare automatstationsdata.De hydrologiska 1-h simuleringarna med MESAN och PTHBV-radar som indata gav en förbättring av resultatet på dygnsbasis, jämfört med en referenssimulering med PTHBV som indata. Nederbörd från radar gav överskattad vattenföring. Skillnaderna mellan 1-d och 1-h simulering illustrerades för enskilda flödestillfällen samt i termer av maximala dygnsvärden.

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  • 182. Arnbjerg-Nielsen, K.
    et al.
    Willems, P.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Beecham, S.
    Pathirana, A.
    Gregersen, I. Bulow
    Madsen, H.
    Nguyen, V. -T-V
    Impacts of climate change on rainfall extremes and urban drainage systems: a review2013Ingår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 68, nr 1, s. 16-28Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    A review is made of current methods for assessing future changes in urban rainfall extremes and their effects on urban drainage systems, due to anthropogenic-induced climate change. The review concludes that in spite of significant advances there are still many limitations in our understanding of how to describe precipitation patterns in a changing climate in order to design and operate urban drainage infrastructure. Climate change may well be the driver that ensures that changes in urban drainage paradigms are identified and suitable solutions implemented. Design and optimization of urban drainage infrastructure considering climate change impacts and co-optimizing these with other objectives will become ever more important to keep our cities habitable into the future.

  • 183.
    Andersson, Jafet
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Zehnder, Alexander J. B.
    Wehrli, Bernhard
    Jewitt, Graham P. W.
    Abbaspour, Karim C.
    Yang, Hong
    Improving Crop Yield and Water Productivity by Ecological Sanitation and Water Harvesting in South Africa2013Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 9, s. 4341-4348Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study quantifies the potential effects of a set of technologies to address wafer and fertility constraints in rain. fed smallholder agriculture in South Africa, namely in situ water harvesting (WH), external WH, and ecological sanitation (Ecosan, fertilization with human urine); We Used the Soil and Water Assessment Tool to model spatiotemporally differentiated effects on maize yield, river flow, evaporation, and transpiration. Ecosan Met some of the plant nitrogen demands, which significantly increased maize yields by 12% and transpiration by 2% on average across South Africa. In situ and external WH did not significantly affect the yield, transpiration or river flow on the South Africa scale. However, external WH. more than doubled the yields for specific seasons and locations. WH particularly increased the lowest yields. Significant, water and nutrient demands remained even with WH and Ecosan management. Additional fertility enhancements raised the yield levels but also the yield variability, whereas soil moisture enhancements improved the yield stability. Hence, coupled policies' addressing both constraints will likely be Most effective for improving food security.

  • 184. Montanari, A.
    et al.
    Young, G.
    Savenije, H. H. G.
    Hughes, D.
    Wagener, T.
    Ren, L. L.
    Koutsoyiannis, D.
    Cudennec, C.
    Toth, E.
    Grimaldi, S.
    Bloeschl, G.
    Sivapalan, M.
    Beven, K.
    Gupta, H.
    Hipsey, M.
    Schaefli, B.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Boegh, E.
    Schymanski, S. J.
    Di Baldassarre, G.
    Yu, B.
    Hubert, P.
    Huang, Y.
    Schumann, A.
    Post, D. A.
    Srinivasan, V.
    Harman, C.
    Thompson, S.
    Rogger, M.
    Viglione, A.
    McMillan, H.
    Characklis, G.
    Pang, Z.
    Belyaev, V.
    "Panta Rhei-Everything Flows": Change in hydrology and society-The IAHS Scientific Decade 2013-20222013Ingår i: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 58, nr 6, s. 1256-1275Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The new Scientific Decade 2013-2022 of IAHS, entitled Panta RheiEverything Flows, is dedicated to research activities on change in hydrology and society. The purpose of Panta Rhei is to reach an improved interpretation of the processes governing the water cycle by focusing on their changing dynamics in connection with rapidly changing human systems. The practical aim is to improve our capability to make predictions of water resources dynamics to support sustainable societal development in a changing environment. The concept implies a focus on hydrological systems as a changing interface between environment and society, whose dynamics are essential to determine water security, human safety and development, and to set priorities for environmental management. The Scientific Decade 2013-2022 will devise innovative theoretical blueprints for the representation of processes including change and will focus on advanced monitoring and data analysis techniques. Interdisciplinarity will be sought by increased efforts to connect with the socio-economic sciences and geosciences in general. This paper presents a summary of the Science Plan of Panta Rhei, its targets, research questions and expected outcomes.

  • 185.
    Bosshard, Thomas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Carambia, M.
    Goergen, K.
    Kotlarski, S.
    Krahe, P.
    Zappa, M.
    Schaer, C.
    Quantifying uncertainty sources in an ensemble of hydrological climate-impact projections2013Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 49, nr 3, s. 1523-1536Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The quantification of uncertainties in projections of climate impacts on river streamflow is highly important for climate adaptation purposes. In this study, we present a methodology to separate uncertainties arising from the climate model (CM), the statistical postprocessing (PP) scheme, and the hydrological model (HM). We analyzed ensemble projections of hydrological changes in the Alpine Rhine (Eastern Switzerland) for the near-term and far-term scenario periods 2024-2050 and 2073-2099 with respect to 1964-1990. For the latter scenario period, the model ensemble projects a decrease of daily mean runoff in summer (-32.2%, range [-45.5% to -8.1%]) and an increase in winter (+41.8%, range [+4.8% to +81.7%]). We applied an analysis of variance model combined with a subsampling procedure to assess the importance of different uncertainty sources. The CMs generally are the dominant source in summer and autumn, whereas, in winter and spring, the uncertainties due to the HMs and the statistical PP gain importance and even partly dominate. In addition, results show that the individual uncertainties from the three components are not additive. Rather, the associated interactions among the CM, the statistical PP scheme, and the HM account for about 5%-40% of the total ensemble uncertainty. The results indicate, in distinction to some previous studies, that none of the investigated uncertainty sources are negligible, and some of the uncertainty is not attributable to individual modeling chain components but rather depends upon interactions. Citation: Bosshard, T., M. Carambia, K. Goergen, S. Kotlarski, P. Krahe, M. Zappa, and C. Schar (2013), Quantifying uncertainty sources in an ensemble of hydrological climate-impact projections, Water Resour. Res., 49, 1523-1536, doi: 10.1029/2011WR011533.

  • 186.
    Temnerud, Johan
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Duker, A.
    Karlsson, S.
    Allard, B.
    Bishop, K.
    Folster, J.
    Kohler, S.
    Spatial patterns of some trace elements in four Swedish stream networks2013Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 10, nr 3, s. 1407-1423Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Four river basins in southern Sweden, with catchment sizes from 0.3 to 127 km(2) (median 1.9), were sampled in October 2007. The 243 samples were analysed for 26 trace elements (Ag, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Ga, Ge, In, La, Li, Mo, Ni, Pb, Sb, Se, Sn, Tl, Ti, U, V and Zn) to identify spatial patterns within drainage networks. The range and median of each element were defined for different stream orders, and relationships to catchment characteristics, including deposition history, were explored. The sampling design made it possible to compare the differences along 40 stream reaches, above and below 53 stream junctions with 107 tributaries and between the 77 inlets and outlets of 36 lakes. The largest concentration differences (at reaches, junctions and lakes) were observed for lakes, with outlets usually having lower concentration compared to the inlets for As, Ba, Be, Bi, Cd, Co, Cr, Ga, Ge, Ni, Pb, Sn, Ti, Tl, U, V and Zn. Significantly lower concentrations were observed for Cd and Co when comparing headwaters with downstream sites in each catchment. Common factor analysis (FA) revealed that As, Bi, Cr, Ga, Ge, Tl and V co-vary positively with Al, Fe and total organic carbon (TOC) and negatively with La, Li and pH. The strong removal of a large number of trace elements when passing through lakes is evident though in the FA, where lake surface coverage plots opposite to many of those elements. Forest volume does not respond in a similar systematic fashion and, surprisingly, the amount of wetland does not relate strongly to either Fe or TOC at any of the rivers. A better understanding of the quantitative removal of organic carbon and iron will aid in understanding trace element fluxes from landscapes rich in organic matter and iron.

  • 187.
    Strombäck, Lena
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Gustafsson, David
    SMHI, Forskningsavdelningen, Hydrologi.
    The Importance of Open Data and Software for Large Scale Hydrological Modelling2013Ingår i: Open water Journal, Vol. 2, nr 1, artikel-id 32Artikel i tidskrift (Refereegranskat)
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  • 188.
    Strombäck, Lena
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Hjerdt, Niclas
    SMHI, Samhälle och säkerhet.
    Eriksson Bram, Lena
    SMHI, Samhälle och säkerhet.
    Lewau, Per
    SMHI.
    Vattenwebb: A Transparent Service to Support Decision Makers in Achieving Improved Water Status2013Ingår i: ISESS 2013, IFIP AICT 413: Information Systems and Applications / [ed] J. Hřebíček et al, IFIP International Federation for Information Processing , 2013, s. 669-678Konferensbidrag (Refereegranskat)
    Abstract [en]

    The vattenwebb.smhi.se service provides simulated as well as measured data on water flow and water quality for Sweden. The available data is used by the water authorities and decision makers in Sweden. The development of the site has been driven by the needs of the users and resulting in a site that is very appreciated by its users. An important aim in the development has been to make the data transparent for the end users, i.e. to explain the model assumptions and data quality in a way that is easy accessible. Therefore the site contains explanations about the model setup, how this data has been computed and information about the performance of the model. In this paper we will describe the service and its features with an emphasis on features used for achieving transparency

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  • 189. Willems, P.
    et al.
    Arnbjerg-Nielsen, K.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Nguyen, V. T. V.
    Climate change impact assessment on urban rainfall extremes and urban drainage: Methods and shortcomings2012Ingår i: Atmospheric research, ISSN 0169-8095, E-ISSN 1873-2895, Vol. 103, s. 106-118Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cities are becoming increasingly vulnerable to flooding because of rapid urbanization, installation of complex infrastructure, and changes in the precipitation patterns caused by anthropogenic climate change. The present paper provides a critical review of the current state-of-the-art methods for assessing the impacts of climate change on precipitation at the urban catchment scale. Downscaling of results from global circulation models or regional climate models to urban catchment scales are needed because these models are not able to describe accurately the rainfall process at suitable high temporal and spatial resolution for urban drainage studies. The downscaled rainfall results are however highly uncertain, depending on the models and downscaling methods considered. This uncertainty becomes more challenging for rainfall extremes since the properties of these extremes do not automatically reflect those of average precipitation. In this paper, following an overview of some recent advances in the development of innovative methods for assessing the impacts of climate change on urban rainfall extremes as well as on urban hydrology and hydraulics, several existing difficulties and remaining challenges in dealing with this assessment are discussed and further research needs are described. (C) 2011 Elsevier B.V. All rights reserved.

  • 190.
    Arheimer, Berit
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Dahne, Joel
    SMHI, Affärsverksamhet.
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Climate Change Impact on Riverine Nutrient Load and Land-Based Remedial Measures of the Baltic Sea Action Plan2012Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, nr 6, s. 600-612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To reduce eutrophication of the Baltic Sea, all nine surrounding countries have agreed upon reduction targets in the HELCOM Baltic Sea Action Plan (BSAP). Yet, monitoring sites and model concepts for decision support are few. To provide one more tool for analysis of water and nutrient fluxes in the Baltic Sea basin, the HYPE model has been applied to the region (called Balt-HYPE). It was used here for experimenting with land-based remedial measures and future climate projections to quantify the impacts of these on water and nutrient loads to the sea. The results suggest that there is a possibility to reach the BSAP nutrient reduction targets by 2100, and that climate change may both aggravate and help in some aspects. Uncertainties in the model results are large, mainly due to the spread of the climate model projections, but also due to the hydrological model.

  • 191.
    Meier, Markus
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Andersson, Helén
    SMHI, Forskningsavdelningen, Oceanografi.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Blenckner, Thorsten
    Chubarenko, Boris
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    Gustafsson, Bo G.
    Hansson, Anders
    Havenhand, Jonathan
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Kuznetsov, Ivan
    MacKenzie, Brian R.
    Muller-Karulis, Barbel
    Neumann, Thomas
    Niiranen, Susa
    Piwowarczyk, Joanna
    Raudsepp, Urmas
    Reckermann, Marcus
    Ruoho-Airola, Tuija
    Savchuk, Oleg P.
    Schenk, Frederik
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Väli, Germo
    SMHI, Forskningsavdelningen, Oceanografi.
    Weslawski, Jan-Marcin
    Zorita, Eduardo
    Comparing reconstructed past variations and future projections of the Baltic Sea ecosystem-first results from multi-model ensemble simulations2012Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 7, nr 3, artikel-id 034005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multi-model ensemble simulations for the marine biogeochemistry and food web of the Baltic Sea were performed for the period 1850-2098, and projected changes in the future climate were compared with the past climate environment. For the past period 1850-2006, atmospheric, hydrological and nutrient forcings were reconstructed, based on historical measurements. For the future period 1961-2098, scenario simulations were driven by regionalized global general circulation model (GCM) data and forced by various future greenhouse gas emission and air-and riverborne nutrient load scenarios (ranging from a pessimistic 'business-as-usual' to the most optimistic case). To estimate uncertainties, different models for the various parts of the Earth system were applied. Assuming the IPCC greenhouse gas emission scenarios A1B or A2, we found that water temperatures at the end of this century may be higher and salinities and oxygen concentrations may be lower than ever measured since 1850. There is also a tendency of increased eutrophication in the future, depending on the nutrient load scenario. Although cod biomass is mainly controlled by fishing mortality, climate change together with eutrophication may result in a biomass decline during the latter part of this century, even when combined with lower fishing pressure. Despite considerable shortcomings of state-of-the-art models, this study suggests that the future Baltic Sea ecosystem may unprecedentedly change compared to the past 150 yr. As stakeholders today pay only little attention to adaptation and mitigation strategies, more information is needed to raise public awareness of the possible impacts of climate change on marine ecosystems.

  • 192. Amaguchi, H.
    et al.
    Kawamura, A.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Takasaki, T.
    Development and testing of a distributed urban storm runoff event model with a vector-based catchment delineation2012Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 420, s. 205-215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recent advances in GIS technology as well as data availability open up new possibilities concerning urban storm runoff modeling. In this paper, a vector-based distributed storm event runoff model - the Tokyo Storm Runoff (TSR) model - is developed and tested for urban runoff analysis using two historical storm events. The set-up of this model is based on urban landscape GIS delineation that faithfully describes the complicated urban land use features in detail. The flow between single spatial elements is based on established hydraulic and hydrological models with equations that describe all aspects of storm runoff generation in an urban environment. The model was set up and evaluated for the small urban lower Ekota catchment in Tokyo Metropolis, Japan. No calibration or tuning was performed, but the general model formulation was used with standard parameter values obtained from the literature. The runoff response to two storm events were simulated; one minor event resulting only in a small-scale flood wave and one major event which inundated parts of the catchment. For both events, the simulated water levels closely reproduced the observed ones. For the major event, also the reported inundation area was well described by the model. It was also demonstrated how the model can be used to evaluate the flow conditions in specific components of the urban hydrological system, which facilitates e.g. evaluation of flood-preventive measures. (C) 2011 Elsevier B.V. All rights reserved.

  • 193. Ruete, Alejandro
    et al.
    Yang, Wei
    SMHI, Forskningsavdelningen, Hydrologi.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Stenseth, Nils Chr.
    Snall, Tord
    Disentangling effects of uncertainties on population projections: climate change impact on an epixylic bryophyte2012Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 279, nr 1740, s. 3098-3105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Assessment of future ecosystem risks should account for the relevant uncertainty sources. This means accounting for the joint effects of climate variables and using modelling techniques that allow proper treatment of uncertainties. We investigate the influence of three of the IPCC's scenarios of greenhouse gas emissions (special report on emission scenarios (SRES)) on projections of the future abundance of a bryophyte model species. We also compare the relative importance of uncertainty sources on the population projections. The whole chain global climate model (GCM)-regional climate model-population dynamics model is addressed. The uncertainty depends on both natural-and model-related sources, in particular on GCM uncertainty. Ignoring the uncertainties gives an unwarranted impression of confidence in the results. The most likely population development of the bryophyte Buxbaumia viridis towards the end of this century is negative: even with a low-emission scenario, there is more than a 65 per cent risk for the population to be halved. The conclusion of a population decline is valid for all SRES scenarios investigated. Uncertainties are no longer an obstacle, but a mandatory aspect to include in the viability analysis of populations.

  • 194.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Gidhagen, Lars
    SMHI, Forskningsavdelningen, Luftmiljö.
    Gamerith, Valentin
    Gruber, Gunter
    Hoppe, Holger
    Kutschera, Peter
    Downscaling of Short-Term Precipitation from Regional Climate Models for Sustainable Urban Planning2012Ingår i: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 4, nr 5, s. 866-887Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A framework for downscaling precipitation from RCM projections to the high resolutions in time and space required in the urban hydrological climate change impact assessment is outlined and demonstrated. The basic approach is that of Delta Change, developed for both continuous and event-based applications. In both cases, Delta Change Factors (DCFs) are calculated which represent the expected future change of some key precipitation statistics. In the continuous case, short-term precipitation from climate projections are analysed in order to estimate DCFs associated with different percentiles in the frequency distribution of non-zero intensities. The DCFs may then be applied to an observed time series, producing a realisation of a future time series. The event-based case involves downscaling of Intensity-Duration-Frequency (IDF) curves based on extreme value analysis of annual maxima using the Gumbel distribution. The resulting DCFs are expressed as a function of duration and frequency (i.e., return period) and may be used to estimate future design storms. The applications are demonstrated in case studies focusing on the expected changes in short-term precipitation statistics until 2100 in the cities of Linz (Austria) and Wuppertal (Germany). The downscaling framework is implemented in the climate service developed within the EU-project SUDPLAN.

  • 195. Musselman, Keith N.
    et al.
    Molotch, Noah P.
    Margulis, Steven A.
    Lehning, Michael
    Gustafsson, David
    SMHI, Forskningsavdelningen, Hydrologi.
    Improved snowmelt simulations with a canopy model forced with photo-derived direct beam canopy transmissivity2012Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 48, artikel-id W10509Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The predictive capacity of a physically based snow model to simulate point-scale, subcanopy snowmelt dynamics is evaluated in a mixed conifer forest, southern Sierra Nevada, California. Three model scenarios each providing varying levels of canopy structure detail were tested. Simulations of three water years initialized at locations of 24 ultrasonic snow depth sensors were evaluated against observations of snow water equivalent (SWE), snow disappearance date, and volumetric soil water content. When canopy model parameters canopy openness and effective leaf area index were obtained from satellite and literature-based sources, respectively, the model was unable to resolve the variable subcanopy snowmelt dynamics. When canopy parameters were obtained from hemispherical photos, the improvements were not statistically significant. However, when the model was modified to accept photo-derived time-varying direct beam canopy transmissivity, the error in the snow disappearance date was reduced by as much as one week and positive and negative biases in melt-season SWE and snow cover duration were significantly reduced. Errors in the timing of soil meltwater fluxes were reduced by 11 days on average. The optimum aggregated temporal model resolution of direct beam canopy transmissivity was determined to be 30 min; hourly averages performed no better than the bulk canopy scenarios and finer time steps did not increase overall model accuracy. The improvements illustrate the important contribution of direct shortwave radiation to subcanopy snowmelt and confirm the known nonlinear melt behavior of snow cover.

  • 196. Weyhenmeyer, Gesa A.
    et al.
    Froberg, Mats
    Karltun, Erik
    Khalili, Maria
    Kothawala, Dolly
    Temnerud, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Tranvik, Lars J.
    Selective decay of terrestrial organic carbon during transport from land to sea2012Ingår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 18, nr 1, s. 349-355Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Numerous studies have estimated carbon exchanges at the landatmosphere interface, more recently also including estimates at the freshwateratmosphere interface. Less attention has been paid to lateral carbon fluxes, in particular to the fate of terrestrial carbon during transport from soils via surface waters to the sea. Using extensive datasets on soil, lake and river mouth chemistry of the boreal/hemiboreal region we determined organic carbon (OC) stocks of the O horizon from catchment soils, annual OC transports through more than 700 lakes (OClakeflux) and the total annual OC transport at Sweden's 53 river mouths (OCseaflux). We show here that a minimum of 0.030.87% yr(-1) of the OC soil stocks need to be exported to lakes in order to sustain the annual OClakeflux. Across Sweden we estimated a total OClakeflux of similar to 2.9 Mtonne yr(-1), which corresponds to similar to 10% of Sweden's total terrestrial net ecosystem production, and it is over 50% higher than the total OCseaflux. The OC loss during transport to the sea follows a simple exponential decay with an OC half-life of similar to 12 years. Water colour, a proxy often used for dissolved humic matter, is similarly lost exponentially but about twice as fast as OC. Thus, we found a selective loss of the coloured portion of soil-derived OC during its transport through inland waters, prior to being discharged into the sea. The selective loss is water residence time dependent, resulting in that the faster the water flows through the landscape the less OC and colour is lost. We conclude that increases in runoff will result in less efficient losses of OC, and particularly of colour, if the time for OC transformations in the landscape shortens. Consequently, OC reaching the sea is likely to become more coloured, and less processed, which can have far-reaching effects on biogeochemical cycles.

  • 197. Lyon, Steve W.
    et al.
    Nathanson, Marcus
    Spans, Andre
    Grabs, Thomas
    Laudon, Hjalmar
    Temnerud, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Bishop, Kevin H.
    Seibert, Jan
    Specific discharge variability in a boreal landscape2012Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 48, artikel-id W08506Artikel i tidskrift (Refereegranskat)
    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.

  • 198.
    Strömqvist, Johan
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Dahne, Joel
    SMHI, Affärsverksamhet.
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Water and nutrient predictions in ungauged basins: set-up and evaluation of a model at the national scale2012Ingår i: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 57, nr 2, s. 229-247Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A dynamic water quality model, HYPE, was applied to a large, data-sparse region to study whether reliable information on water quantity and water quality could be obtained for both gauged and ungauged waterbodies. The model (called S-HYPE) was set up for all of Sweden (similar to 450 000 km(2)), divided into sub-basins with an average area of 28 km(2). Readily available national databases were used for physiographic data, emissions and agricultural practices, fixed values for representative years were used. Daily precipitation and temperature were used as the dynamic forcing of the model. Model evaluation was based on data from several hundred monitoring sites, of which approximately 90% had not been used in calibration on a daily scale. Results were evaluated using the Nash-Sutcliffe efficiency (NSE), correlation and relative errors: 92% of the spatial variation was explained for specific water discharge, and 88% and 59% for total nitrogen and total phosphorus concentrations, respectively. Day-to-day variations were modelled with satisfactory results for water discharge and the seasonal variation of nitrogen concentrations was also generally well captured. In 20 large, unregulated rivers the median NSE for water discharge was 0.84, and the corresponding number for 76 partly-regulated river basins was 0.52. In small basins, the NSE was typically above 0.6. These major achievements relative to previous similar experiments were ascribed to the step-wise calibration process using representative gauged basins and the use of amodelling concept, whereby coefficients are linked to physiographic variables rather than to specific sites.

  • 199.
    Arheimer, Berit
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Dahne, Joel
    SMHI, Affärsverksamhet.
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Strömqvist, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Water and nutrient simulations using the HYPE model for Sweden vs. the Baltic Sea basin - influence of input-data quality and scale2012Ingår i: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 43, nr 4, s. 315-329Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Water resource management is often based on numerical models, and large-scale models are sometimes used for international strategic agreements. Sometimes the modelled area entails several political entities and river basins. To avoid methodological bias in results, methods and databases should be homogenous across political and geophysical boundaries, but this may involve fewer details and more assumptions. This paper quantifies the uncertainty when the same model code is applied using two different input datasets; a more detailed one for the country of Sweden (S-HYPE) and a more general one for the entire Baltic Sea basin (Balt-HYPE). Results from the two model applications were compared for the Swedish landmass and for two specific Swedish river basins. The results show that both model applications may be useful in providing spatial information of water and nutrients at various scales. For water discharge, most relative errors are <10% for S-HYPE and <25% for Balt-HYPE. Both applications reproduced the most mean concentration for nitrogen within 25% of the observed mean values, but phosphorus showed a larger scatter. Differences in model set-up were reflected in the simulation of both spatial and temporal dynamics. The most sensitive data were precipitation/temperature, agriculture and model parameter values.

  • 200. Olsson, Johanna Alkan
    et al.
    Jonsson, Anna C.
    Andersson, Lotta
    SMHI, Samhälle och säkerhet.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    A model-supported participatory process for nutrient management: a socio-legal analysis of a bottom-up implementation of the EU Water Framework Directive2011Ingår i: International Journal of Agricultural Sustainability, ISSN 1473-5903, E-ISSN 1747-762X, Vol. 9, nr 2, s. 379-389Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A methodology for local stakeholders' involvement in water management using a catchment model as a platform for dialogue has been developed and tested in the Kaggebo Bay drainage area in the southeast of Sweden. The process involved farmers, rural households not connected to municipal wastewater treatment facilities, local and regional authorities as well as different water and agricultural experts. This paper aims to assess whether and how the methodology has succeeded in encouraging social learning and promoting action and which barriers can be identified. The assessment shows that the methodology is able to create confidence in the process and increase the willingness to act as the methodology was able to adapt the form and content of the dialogue to better fit the cognitive and relational needs of involved stakeholders. It is also shown that the process may lead to a probable improvement of the eutrophication situation. However, if these types of processes are to serve not only as a basis for social learning and action at the local level, but also as the basis for a broader process of societal learning, then a mechanism to confer local ideas to the regional and national levels has to be clarified.

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