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  • 161.
    Bosshard, Thomas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Kotlarski, Sven
    Zappa, Massimiliano
    Schaer, Christoph
    Hydrological Climate-Impact Projections for the Rhine River: GCM-RCM Uncertainty and Separate Temperature and Precipitation Effects2014Ingår i: Journal of Hydrometeorology, ISSN 1525-755X, E-ISSN 1525-7541, Vol. 15, nr 2, s. 697-713Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate change is expected to affect the hydrological cycle, with considerable impacts on water resources. Climate-induced changes in the hydrology of the Rhine River (Europe) are of major importance for the riparian countries, as the Rhine River is the most important European waterway, serves as a freshwater supply source, and is prone to floods and droughts. Here regional climate model data from the Ensemble-Based Predictions of Climate Changes and their Impacts (ENSEMBLES) project is used to drive the hydrological model Precipitation-Runoff-Evapotranspiration-Hydrotope (PREVAH) and to assess the impact of climate change on the hydrology in the Rhine basin. Results suggest increases in monthly mean runoff during winter and decreases in summer. At the gauge Cologne and for the period 2070-99 under the A1B scenario of the Special Report on Emissions Scenarios, projected decreases in summer vary between -9% and -40% depending on the climate model used, while increases in winter are in the range of +4% to +51%. These projected changes in mean runoff are generally consistent with earlier studies, but the derived spread in the runoff projections appears to be larger. It is demonstrated that temperature effects (e.g., through altered snow processes) dominate in the Alpine tributaries, while precipitation effects dominate in the lower portion of the Rhine basin. Analyses are also presented for selected extreme runoff indices.

  • 162.
    Bergstrand, Marie
    et al.
    SMHI, Samhälle och säkerhet.
    Asp, Sara-Sofia
    SMHI, Samhälle och säkerhet.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Nationwide hydrological statistics for Sweden with high resolution using the hydrological model S-HYPE2014Ingår i: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 45, nr 3, s. 349-356Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A first version of nationally covering hydrological statistics for Sweden based on the S-HYPE hydrological model for the period 1961-2010 is described. A key feature of the proposed method is that observed data are used as input wherever such data are available, and the model is used for interpolation in between stations. Short observation records are automatically extended by the use of the model. High flow statistics typically differed by about +/- 10% from observations. The corresponding number for low flow was about +/- 30%. High flow peaks were usually simulated slightly too low whereas low flows were too high. In a relative sense low flows were more uncertain than high flows. The mean flow was relatively certain. The annual maximum values were fitted to a Gumbel distribution, by the method of moments, for each subbasin. Flood statistics were then calculated up to a return period of 50 years. According to a Kolmogorov-Smirnov test, less than 1% of the fitted distributions were rejected. Most rejections occurred in regulated systems, due to difficulties in simulating regulation strategies, but also due to uncertainties in the precipitation input in the mountainous region. Results at small scale are very uncertain. The proposed method is a cost-effective way of calculating hydrological statistics with high spatial resolution.

  • 163. Sponseller, Ryan A.
    et al.
    Temnerud, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Bishop, Kevin
    Laudon, Hjalmar
    Patterns and drivers of riverine nitrogen (N) across alpine, subarctic, and boreal Sweden2014Ingår i: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 120, nr 1-3, s. 105-120Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Concentrations of nitrogen (N) in surface waters reflect the export of different organic and inorganic forms from terrestrial environments and the modification of these resources within aquatic habitats. We evaluated the relative influence of terrestrial ecosystem state factors, anthropogenic gradients, and aquatic habitat variables on patterns of N concentration in streams and rivers across Sweden. We analyzed data from 115 national monitoring stations distributed along a 1,300 km latitudinal gradient, draining catchments that differed by more than 10 A degrees C in mean annual temperature (MAT), and more than five orders of magnitude in area. Regional trends in total organic nitrogen (TON) and carbon:nitrogen (C:N) were closely linked to broad-scale gradients in state factors (e.g., MAT), reflecting the importance of long-term ecosystem development on terrestrial organic matter accrual and export. In contrast, trends in nitrate (NO3 (-)), the dominant form of inorganic N, were largely unrelated to state factors, but instead were closely connected to gradients related to anthropogenic inputs (e.g., agricultural cover). Despite large differences in drainage size and cover by lakes and wetlands among sites, these descriptors of the aquatic environment had little influence on spatial patterns of N chemistry. The temporal variability in N concentrations also differed between forms: inorganic N was strongly seasonal, with peaks during dormant periods that underscore biotic control over terrestrial losses of limiting resources. Organic N showed comparatively weaker seasonality, but summertime increases suggest temperature-driven patterns of soil TON production and export-temporal signals which were modified by variables that govern water residence time within catchments. Unique combinations of regional predictors reflect basic differences in the cycling of organic versus inorganic N and highlight variation in the sensitivity of these different N forms to environmental changes that directly alter inputs of resources, or indirectly modify terrestrial ecosystems through shifts in species composition, rates of forest productivity, soil development, and hydrologic routing.

  • 164.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Simonsson, Lennart
    SMHI, Forskningsavdelningen, Hydrologi.
    Ridal, Martin
    SMHI, Forskningsavdelningen, Meteorologi.
    Rainfall nowcasting: predictability of short-term extremes in Sweden2014Ingår i: Urban Water Journal, ISSN 1573-062X, Vol. 11, nr 7, s. 605-615Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Our current knowledge of the character of rainfall events in Sweden associated with extreme short-term accumulations and their predictability by forecasting, is very limited. In this study, observations from automatic stations and weather radars in Sweden were analysed to identify and characterise extreme short-term events. Often shorter-duration (1-6 h) extreme events were associated with small-scale structures, dominated by single cells, and longer-duration (12-24 h) events with less variable, larger-scale fields. For lead time 3 h,,20% of the events were forecasted at the correct place with an error of <25% by the operational Swedish nowcasting system. If allowing for a 25 km displacement of the forecasted events, the hit rate increased by 10-15 percentage points. Some predictability was found for lead time 8 h but not for 24 h. The results suggest a potential added gain of increasing the temporal resolution of the Swedish flood forecasting system to sub-daily steps.

  • 165. Juston, John
    et al.
    Jansson, Per-Erik
    Gustafsson, David
    SMHI, Forskningsavdelningen, Hydrologi.
    Rating curve uncertainty and change detection in discharge time series: case study with 44-year historic data from the Nyangores River, Kenya2014Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, nr 4, s. 2509-2523Artikel i tidskrift (Refereegranskat)
    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.

  • 166.
    Donnelly, Chantal
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Yang, Wei
    SMHI, Forskningsavdelningen, Hydrologi.
    Dahne, Joel
    SMHI, Affärsverksamhet.
    River discharge to the Baltic Sea in a future climate2014Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 122, nr 1-2, s. 157-170Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study reports on new projections of discharge to the Baltic Sea given possible realisations of future climate and uncertainties regarding these projections. A high-resolution, pan-Baltic application of the Hydrological Predictions for the Environment (HYPE) model was used to make transient simulations of discharge to the Baltic Sea for a mini-ensemble of climate projections representing two high emissions scenarios. The biases in precipitation and temperature adherent to climate models were adjusted using a Distribution Based Scaling (DBS) approach. As well as the climate projection uncertainty, this study considers uncertainties in the bias-correction and hydrological modelling. While the results indicate that the cumulative discharge to the Baltic Sea for 2071 to 2100, as compared to 1971 to 2000, is likely to increase, the uncertainties quantified from the hydrological model and the bias-correction method show that even with a state-of-the-art methodology, the combined uncertainties from the climate model, bias-correction and impact model make it difficult to draw conclusions about the magnitude of change. It is therefore urged that as well as climate model and scenario uncertainty, the uncertainties in the bias-correction methodology and the impact model are also taken into account when conducting climate change impact studies.

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  • 167.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Foster, Kean
    SMHI, Forskningsavdelningen, Hydrologi.
    Short-term precipitation extremes in regional climate simulations for Sweden2014Ingår i: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 45, nr 3, s. 479-489Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate change is expected to generate higher short-term precipitation intensities, which may have negative consequences in terms of, for example, increased risk of flooding and sewer overflow. In this study, extreme precipitation for durations between 30 min and 1 day in simulations with the RCA3 regional climate model (RCM) for Sweden are analysed. As compared with daily observations in the period 1961-2010, the simulated extremes are found to be overall realistic with respect to magnitude, spatial homogeneity and temporal variability. In the ensemble of future projections, from 1981 to 2010 the 10-year 30-min precipitation will increase by 6% until 2011-2040, 15% until 2041-2070 and 23% until 2071-2100. The increase decreases with increasing duration and at the daily scale the percentage values are approximately halved. The values are largely consistent with earlier estimates. Assessment of the impacts on the results of the spatial resolution and the specific RCM used indicated possibilities of both smaller and larger future increases.

  • 168. Hall, J.
    et al.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Borga, M.
    Brazdil, R.
    Claps, P.
    Kiss, A.
    Kjeldsen, T. R.
    Kriauciuniene, J.
    Kundzewicz, Z. W.
    Lang, M.
    Llasat, M. C.
    Macdonald, N.
    McIntyre, N.
    Mediero, L.
    Merz, B.
    Merz, R.
    Molnar, P.
    Montanari, A.
    Neuhold, C.
    Parajka, J.
    Perdigao, R. A. P.
    Plavcova, L.
    Rogger, M.
    Salinas, J. L.
    Sauquet, E.
    Schaer, C.
    Szolgay, J.
    Viglione, A.
    Bloeschl, G.
    Understanding flood regime changes in Europe: a state-of-the-art assessment2014Ingår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 18, nr 7, s. 2735-2772Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is growing concern that flooding is becoming more frequent and severe in Europe. A better understanding of flood regime changes and their drivers is therefore needed. The paper reviews the current knowledge on flood regime changes in European rivers that has traditionally been obtained through two alternative research approaches. The first approach is the data-based detection of changes in observed flood events. Current methods are reviewed together with their challenges and opportunities. For example, observation biases, the merging of different data sources and accounting for nonlinear drivers and responses. The second approach consists of modelled scenarios of future floods. Challenges and opportunities associated with flood change scenarios are discussed such as fully accounting for uncertainties in the modelling cascade and feedbacks. To make progress in flood change research, we suggest that a synthesis of these two approaches is needed. This can be achieved by focusing on long duration records and flood-rich and flood-poor periods rather than on short duration flood trends only, by formally attributing causes of observed flood changes, by validating scenarios against observed flood regime dynamics, and by developing low-dimensional models of flood changes and feedbacks. The paper finishes with a call for a joint European flood change research network.

  • 169.
    Pechlivanidis, Ilias
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Jackson, B.
    McMillan, H.
    Gupta, H.
    Use of an entropy-based metric in multiobjective calibration to improve model performance2014Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 50, nr 10, s. 8066-8083Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Parameter estimation for hydrological models is complicated for many reasons, one of which is the arbitrary emphasis placed, by most traditional measures of fit, on various magnitudes of the model residuals. Recent research has called for the development of robust diagnostic measures that provide insights into which model structural components and/or data may be inadequate. In this regard, the flow duration curve (FDC) represents the historical variability of flow and is considered to be an informative signature of catchment behavior. Here we investigate the potential of using the recently developed conditioned entropy difference metric (CED) in combination with the Kling-Gupta efficiency (KGE). The CED respects the static information contained in the flow frequency distribution (and hence the FDC), but does not explicitly characterize temporal dynamics. The KGE reweights the importance of various hydrograph components (correlation, bias, variability) in a way that has been demonstrated to provide better model calibrations than the commonly used Nash-Sutcliffe efficiency, while being explicitly time sensitive. We employ both measures within a multiobjective calibration framework and achieve better performance over the full range of flows than obtained by single-criteria approaches, or by the common multiobjective approach that uses log-transformed and untransformed data to balance fitting of low and high flow periods. The investigation highlights the potential of CED to complement KGE (and vice versa) during model identification. It is possible that some of the complementarity is due to CED representing more information from moments >2 than KGE or other common metrics. We therefore suggest that an interesting way forward would be to extend KGE to include higher moments, i.e., use different moments as multiple criteria. Key Points <list id="wrcr21161-list-0001" list-type="bulleted"> <list-item id="wrcr21161-li-0001">CED provides an appropriate quantitative measure of fit to the FDC <list-item id="wrcr21161-li-0002">Complements between CED and KGE extracted flow information <list-item id="wrcr21161-li-0003">CED-KGE achieves better performance than single or common multiobjectives <doi origin="wiley" registered="yes">10.1002/(ISSN)1944-7973</doi

  • 170. Grimvall, Anders
    et al.
    von Bromssen, Claudia
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Using process-based models to filter out natural variability in observed concentrations of nitrogen and phosphorus in river water2014Ingår i: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 186, nr 8, s. 5135-5152Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Advances in process-based modelling of loads of nitrogen and phosphorus carried by rivers have created new possibilities to interpret time series of water quality data. We examined how model runs with constant anthropogenic forcing can be used to estimate and filter out weather-driven variation in observational data and, thereby, draw attention to other features of such data. An assessment of measured and modelled nutrient concentrations at the outlets of 45 Swedish rivers provided promising results for total nitrogen. In particular, joint analyses of observational data and outputs from the catchment model S-HYPE strengthened the evidence that downward trends in nitrogen were due to mitigation measures in agriculture. Evaluation of modelled and observed total phosphorus concentrations revealed considerable bias in the collection or chemical analysis of water samples and also identified weaknesses in the model outputs. Together, our results highlight the need for more efficient two-way communication between environmental modelling and monitoring.

  • 171. Hrachowitz, M.
    et al.
    Savenije, H. H. G.
    Bloeschl, G.
    McDonnell, J. J.
    Sivapalan, M.
    Pomeroy, J. W.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Blume, T.
    Clark, M. P.
    Ehret, U.
    Fenicia, F.
    Freer, J. E.
    Gelfan, A.
    Gupta, H. V.
    Hughes, D. A.
    Hut, R. W.
    Montanari, A.
    Pande, S.
    Tetzlaff, D.
    Troch, P. A.
    Uhlenbrook, S.
    Wagener, T.
    Winsemius, H. C.
    Woods, R. A.
    Zehe, E.
    Cudennec, C.
    A decade of Predictions in Ungauged Basins (PUB)a review2013Ingår i: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 58, nr 6, s. 1198-1255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Prediction in Ungauged Basins (PUB) initiative of the International Association of Hydrological Sciences (IAHS), launched in 2003 and concluded by the PUB Symposium 2012 held in Delft (23-25 October 2012), set out to shift the scientific culture of hydrology towards improved scientific understanding of hydrological processes, as well as associated uncertainties and the development of models with increasing realism and predictive power. This paper reviews the work that has been done under the six science themes of the PUB Decade and outlines the challenges ahead for the hydrological sciences community.

  • 172.
    Donnelly, Chantal
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Rosberg, Jörgen
    SMHI, Forskningsavdelningen, Hydrologi.
    Isberg, Kristina
    SMHI, Forskningsavdelningen, Hydrologi.
    A validation of river routing networks for catchment modelling from small to large scales2013Ingår i: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 44, nr 5, s. 917-925Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Underpinning all hydrological simulations is an estimate of the catchment area upstream of a point of interest. Locally, the delineation of a catchment and estimation of its area is usually done using fine scale maps and local knowledge, but for large-scale hydrological modelling, particularly continental and global scale modelling, this level of detailed data analysis is not practical. For large-scale hydrological modelling, remotely sensed and hydrologically conditioned river routing networks, such as HYDROlk and HydroSHEDS, are often used. This study evaluates the accuracy of the accumulated upstream area in each gridpoint given by the networks. This is useful for evaluating the ability of these data sets to delineate catchments of varying scale for use in hydrological models. It is shown that the higher resolution HydroSHEDS data set gives better results than the HYDROlk data set and that accuracy decreases with decreasing basin scale. In ungauged basins, or where other local catchment area data are not available, the validation made in this study can be used to indicate the likelihood of correctly delineating catchments of different scales using these river routing networks.

  • 173.
    Wilk, Julie
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Andersson, Lotta
    SMHI, Samhälle och säkerhet.
    Warburton, Michele
    Adaptation to climate change and other stressors among commercial and small-scale South African farmers2013Ingår i: Regional Environmental Change, ISSN 1436-3798, E-ISSN 1436-378X, Vol. 13, nr 2, s. 273-286Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Commercial and small-scale farmers in South Africa are exposed to many challenges. Interviews with 44 farmers in the upper Thukela basin, KwaZulu-Natal, were conducted to identify common and specific challenges for the two groups and adaptive strategies for dealing with the effects of climate and other stressors. This work was conducted as part of a larger participatory project with local stakeholders to develop a local adaptation plan for coping with climate variability and change. Although many challenges related to exposure to climate variability and change, weak agricultural policies, limited governmental support, and theft were common to both farming communities, their adaptive capacities were vastly different. Small-scale farmers were more vulnerable due to difficulties to finance the high input costs of improved seed varieties and implements, limited access to knowledge and agricultural techniques for water and soil conservation and limited customs of long-term planning. In addition to temperature and drought-related challenges, small-scale farmers were concerned about soil erosion, water logging and livestock diseases, challenges for which the commercial farmers already had efficient adaptation strategies in place. The major obstacle hindering commercial farmers with future planning was the lack of clear directives from the government, for example, with regard to issuing of water licences and land reform. Enabling agricultural communities to procure sustainable livelihoods requires implementation of strategies that address the common and specific challenges and strengthen the adaptive capacity of both commercial and small-scale farmers. Identified ways forward include knowledge transfer within and across farming communities, clear governmental directives and targeted locally adapted finance programmes.

  • 174.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Amaguchi, Hideo
    Alsterhag, Elin
    Daverhog, Maria
    Adrian, Per-Erik
    Kawamura, Akira
    Adaptation to climate change impacts on urban storm water: a case study in Arvika, Sweden2013Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 116, nr 2, s. 231-247Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Already today, the functionality of many sewer and storm water systems are not up to the required standards and consequently flooding problems are experienced in case of heavy storms. System upgrades are required, which are however complicated by the expected future increase in short-term rainfall intensities as a result of climate change. In this case study, focusing on the town of Arvika, Sweden, this issue is investigated in three main steps. In the first, extreme value analyses of 30-min rainfall from an ensemble of climate projections are carried out to estimate the future increase and generate a future design storm. In the second, the existing system's response to both today's and future design storms are simulated by a coarse sewer model setup (MOUSE) and a detailed coupled surface-sewer model setup (TSR). In the third and final step, system upgrades are designed and evaluated by both models. The results indicate an increase by 10-30 % of today's short-term rainfall extremes by the end of the century. Upgrading the system to achieve a satisfactory performance for the future design storm would cost approximately twice as much as an upgrade based on today's design storm.

  • 175. Anastasiadis, Stavros
    et al.
    Boglis, Argiris
    Pechlivanidis, Ilias
    SMHI, Forskningsavdelningen, Hydrologi.
    Lekkas, Demetris F.
    Baltas, Evaggelos
    APPLICATION OF GIS BASED CLARK'S UNIT HYDROGRAPH AND TRANSFER FUNCTION MODEL TO DESCRIBE RUNOFF RESPONSE IN A SMALL CATCHMENT, CASE STUDY: LYKOREMMA RIVER, GREECE2013Ingår i: Fresenius Environmental Bulletin, ISSN 1018-4619, E-ISSN 1610-2304, Vol. 22, nr 7B, s. 2152-2158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hydrologic community has recently focused substantial attention on ungauged or poorly gauged catchments, since hydrological prediction under these conditions is highly uncertain, but represents the majority of practical applications. Catchments in Greece are usually ungauged, due to resource constrains, whilst in gauged areas the period of record is often short for safe estimation of highly parameterised hydrological models. This paper is driven by the Prediction in Ungauged Basins initiative aiming to estimate catchment responses using readily available data, i.e. topographical, soil and land use information. The parsimonious rainfall-runoff model developed in a Geographical Information System (GIS) environment is based on the Clark's synthetic unit hydrograph technique to estimate the hydrological response. The method requires estimation of the time of concentration (based on the curve number), the storage attenuation coefficient and the time area histogram of the catchment. The models further compared with a data-based modelling approach using a Transfer Function and the simulated streamflow is analysed to investigate similarities as well as to better understand possible extensions of the resulting unit hydrograph. A case study using 10-minute observed data from the 15 km(2) Lykorema catchment, Attica, Greece, highlights the potential of the GIS-based model to predict, at least, the dynamic characteristics of the runoff response in ungauged or poorly gauged catchments.

  • 176. Parkes, B. L.
    et al.
    Wetterhall, Fredrik
    SMHI, Forskningsavdelningen, Hydrologi.
    Pappenberger, F.
    He, Y.
    Malamud, B. D.
    Cloke, H. L.
    Assessment of a 1-hour gridded precipitation dataset to drive a hydrological model: a case study of the summer 2007 floods in the Upper Severn, UK2013Ingår i: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 44, nr 1, s. 89-105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study a gridded hourly 1-km precipitation dataset for a meso-scale catchment (4,062 km(2)) of the Upper Severn River, UK was constructed using rainfall radar data to disaggregate a daily precipitation (rain gauge) dataset. The dataset was compared to an hourly precipitation dataset created entirely from rainfall radar data. Results found that when assessed against gauge readings and as input to the Lisflood-RR hydrological model, the rain gauge/radar disaggregated dataset performed the best suggesting that this simple method of combining rainfall radar data with rain gauge readings can provide temporally detailed precipitation datasets for calibrating hydrological models.

  • 177.
    Strombäck, Lena
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Foster, Kean
    SMHI, Forskningsavdelningen, Hydrologi.
    Rosberg, Jörgen
    SMHI, Forskningsavdelningen, Hydrologi.
    Data and Provenance Management for Climate Effect Studies. Adaption of Climate Data with Distribution Based Scaling for Hydrological Simulations.2013Ingår i: Proceedings of DBKDA 2013, Seville, Spain., 2013Konferensbidrag (Refereegranskat)
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  • 178.
    Riml, Joakim
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Worman, Anders
    Kunkel, Uwe
    Radke, Michael
    Evaluating the fate of six common pharmaceuticals using a reactive transport model: Insights from a stream tracer test2013Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 458, s. 344-354Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quantitative information regarding the capacity of rivers to self-purify pharmaceutical residues is limited. To bridge this knowledge gap, we present a methodology for quantifying the governing processes affecting the fate of pharmaceuticals in streaming waters and, especially, to evaluate their relative significance for tracer observations. A tracer test in Sava Brook, Sweden was evaluated using a coupled physical-biogeochemical model framework containing surface water transport together with a representation of transient storage in slow/immobile zones of the stream, which are presumably important for the retention and attenuation of pharmaceuticals. To assess the key processes affecting the environmental fate of the compounds, we linked the uncertainty estimates of the reaction rate coefficients to the relative influence of transformation and sorption that occurred in different stream environments. The hydrological and biogeochemical contributions to the fate of the pharmaceuticals were decoupled, and the results indicate a moderate hydrological retention in the hyporheic zone as well as in the densely vegetated parts of the stream. Biogeochemical reactions in these transient storage zones further affected the fate of the pharmaceuticals, and we found that sorption was the key process for bezafibrate, metoprolol, and naproxen, while primary transformation was the most important process for clofibric acid and ibuprofen. Conversely, diclofenac was not affected by sorption or transformation. (C) 2013 Elsevier B.V. All rights reserved.

  • 179.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Foster, Kean
    SMHI, Forskningsavdelningen, Hydrologi.
    Extrem korttidsnederbörd i klimatprojektioner för Sverige2013Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Klimatförändringen förväntas leda till mera intensiv korttidsnederbörd, vilket kan få negativa konsekvenser för t.ex. urban hydrologi. I denna studie analyseras extrem korttidsnederbörd i Sverige simulerad med den regionala klimatmodellen RCA3. En observerad svag ökning från period 1961-1990 till period 1981-2010 av dygnsnederbörd med 10 års återkomsttid kan kvalitativt återskapas av RCA3-modellen, både när den drivs med meteorologisk återanalys (ERA40) och med en ensemble av sex globala klimatprojektioner. Detta är ingen garanti för att simulerade framtida förändringar är korrekta, men tyder på en förmåga att beskriva förändringar av dygnsextremer ifall randvillkoren är de rätta. I ensemblen av framtida projektioner ökar 10-års 30-min nederbörden med 6% från 1981-2010 till 2011-2040, 15% till 2041-2070 och 23% till 2071-2100. Ökningen minskar med ökande varaktighet och på dygnsskala är de relativa förändringarna ungefär halverade. Analyser av inverkan på resultatet av dels den specifika modell som användes (RCA3), dels dess rumsliga upplösning (50 km) antydde möjligheter till både lägre och högre värden på de framtida förändringarna. En syntes av den forskning kring framtida korttidsextremer som utförts i Sverige till dags dato tyder på en förväntad ökning av extrem korttidsnederbörd (≤ 1 tim) med 10% till mitten av seklet (2050) och 25% till slutet av seklet (2100). Låga och höga uppskattingar bedöms till ±10 procentenheter från de förväntade värdena men även större avvikelser är möjliga. För dygnsextremer förväntas ökningen bli fem procentenheter lägre

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  • 180.
    Wetterhall, Fredrik
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Pappenberger, F.
    Alfieri, L.
    Cloke, H. L.
    Thielen-del Pozo, J.
    Balabanova, S.
    Danhelka, J.
    Vogelbacher, A.
    Salamon, P.
    Carrasco, I.
    Cabrera-Tordera, A. J.
    Corzo-Toscano, M.
    Garcia-Padilla, M.
    Garcia-Sanchez, R. J.
    Ardilouze, C.
    Jurela, S.
    Terek, B.
    Csik, A.
    Casey, J.
    Stankunavicius, G.
    Ceres, V.
    Sprokkereef, E.
    Stam, J.
    Anghel, E.
    Vladikovic, D.
    Eklund, C. Alionte
    Hjerdt, N.
    Djerv, H.
    Holmberg, F.
    Nilsson, J.
    Nystrom, K.
    Susnik, M.
    Hazlinger, M.
    Holubecka, M.
    HESS Opinions "Forecaster priorities for improving probabilistic flood forecasts"2013Ingår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 17, nr 11, s. 4389-4399Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrological ensemble prediction systems (HEPS) have in recent years been increasingly used for the operational forecasting of floods by European hydrometeorological agencies. The most obvious advantage of HEPS is that more of the uncertainty in the modelling system can be assessed. In addition, ensemble prediction systems generally have better skill than deterministic systems both in the terms of the mean forecast performance and the potential forecasting of extreme events. Research efforts have so far mostly been devoted to the improvement of the physical and technical aspects of the model systems, such as increased resolution in time and space and better description of physical processes. Developments like these are certainly needed; however, in this paper we argue that there are other areas of HEPS that need urgent attention. This was also the result from a group exercise and a survey conducted to operational forecasters within the European Flood Awareness System (EFAS) to identify the top priorities of improvement regarding their own system. They turned out to span a range of areas, the most popular being to include verification of an assessment of past forecast performance, a multi-model approach for hydrological modelling, to increase the forecast skill on the medium range (> 3 days) and more focus on education and training on the interpretation of forecasts. In light of limited resources, we suggest a simple model to classify the identified priorities in terms of their cost and complexity to decide in which order to tackle them. This model is then used to create an action plan of short-, medium-and long-term research priorities with the ultimate goal of an optimal improvement of EFAS in particular and to spur the development of operational HEPS in general.

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