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  • 251. Parkes, B. L.
    et al.
    Wetterhall, Fredrik
    SMHI, Research Department, Hydrology.
    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, UK2013In: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 44, no 1, p. 89-105Article in journal (Refereed)
    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.

  • 252. Pechlivanidis, G. I.
    et al.
    Keramaris, E.
    Pechlivanidis, Ilias
    SMHI, Research Department, Hydrology.
    Samaras, G. A.
    Shear stress estimation in the linear zone over impermeable and permeable beds in open channels2015In: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986, Vol. 54, no 8, p. 2181-2189Article in journal (Refereed)
    Abstract [en]

    This paper investigates the shear stresses in the linear zone of open channel flows with permeable and impermeable bed. The permeable bed is simulated using a flexible vegetation of 2 cm thickness. Laboratory experiments were used for the calculation of the turbulent velocity profiles. The measurements were obtained using a two-dimensional (2D) particle image velocimetry (PIV). This optical method of fluid visualization is used to obtain instantaneous velocity measurements related properties in the fluids. The PIV method assumes that the particles of a fluid faithfully follow the flow dynamics; hence the motion of these seeding particles is used to calculate the dynamic characteristics of the flow. The measurements were conducted at a 12 x 10 cm(2) region located 4 m away from the channel's entrance, where the flow is considered fully developed. The uniformity of the flow was checked measuring the flow depth at two cross-sections (2 m distance between the two regions). The total discharge was estimated using a calibrated venture apparatus. Measurements of velocity were taken for the horizontal channel slope. Results showed that the type of bed can significantly influence the shear stress definition in the linear zone.

  • 253.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Large-scale hydrological modelling by using modified PUB recommendations: the India-HYPE case2015In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 19, no 11, p. 4559-4579Article in journal (Refereed)
    Abstract [en]

    The scientific initiative Prediction in Ungauged Basins (PUB) (2003-2012 by the IAHS) put considerable effort into improving the reliability of hydrological models to predict flow response in ungauged rivers. PUB's collective experience advanced hydrologic science and defined guidelines to make predictions in catchments without observed runoff data. At present, there is a raised interest in applying catchment models to large domains and large data samples in a multi-basin manner, to explore emerging spatial patterns or learn from comparative hydrology. However, such modelling involves additional sources of uncertainties caused by the inconsistency between input data sets, i.e. particularly regional and global databases. This may lead to inaccurate model parameterisation and erroneous process understanding. In order to bridge the gap between the best practices for flow predictions in single catchments and multi-basins at the large scale, we present a further developed and slightly modified version of the recommended best practices for PUB by Takeuchi et al. (2013). By using examples from a recent HYPE (Hydrological Predictions for the Environment) hydrological model set-up across 6000 subbasins for the Indian subcontinent, named India-HYPE v1.0, we explore the PUB recommendations, identify challenges and recommend ways to overcome them. We describe the work process related to (a) errors and inconsistencies in global databases, unknown human impacts, and poor data quality; (b) robust approaches to identify model parameters using a stepwise calibration approach, remote sensing data, expert knowledge, and catchment similarities; and (c) evaluation based on flow signatures and performance metrics, using both multiple criteria and multiple variables, and independent gauges for "blind tests". The results show that despite the strong physiographical gradient over the subcontinent, a single model can describe the spatial variability in dominant hydrological processes at the catchment scale. In addition, spatial model deficiencies are used to identify potential improvements of the model concept. Eventually, through simultaneous calibration using numerous gauges, the median Kling-Gupta efficiency for river flow increased from 0.14 to 0.64. We finally demonstrate the potential of multi-basin modelling for comparative hydrology using PUB, by grouping the 6000 subbasins based on similarities in flow signatures to gain insights into the spatial patterns of flow generating processes at the large scale.

  • 254.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Hundecha, Yeshewatesfa
    SMHI, Research Department, Hydrology.
    Huang, S.
    Aich, V.
    Samaniego, L.
    Eisner, S.
    Shi, P.
    Analysis of hydrological extremes at different hydro-climatic regimes under present and future conditions2017In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 141, no 3, p. 467-481Article in journal (Refereed)
  • 255.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Hundecha, Yeshewatesfa
    SMHI, Research Department, Hydrology.
    Huang, S.
    Aich, V.
    Samaniego, L.
    Eisner, S.
    Shi, P.
    Analysis of hydrological extremes at different hydro-climatic regimes under present and future conditions.2016In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480Article in journal (Refereed)
  • 256. Pechlivanidis, Ilias G.
    et al.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Sharma, Devesh
    Sharma, K. C.
    Multi-Basin Modelling of Future Hydrological Fluxes in the Indian Subcontinent2016In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 8, no 5, article id 177Article in journal (Refereed)
    Abstract [en]

    The impact of climate change on the hydro-climatology of the Indian subcontinent is investigated by comparing statistics of current and projected future fluxes resulting from three RCP scenarios (RCP2.6, RCP4.5, and RCP8.5). Climate projections from the CORDEX-South Asia framework have been bias-corrected using the Distribution-Based Scaling (DBS) method and used to force the HYPE hydrological model to generate projections of evapotranspiration, runoff, soil moisture deficit, snow depth, and applied irrigation water to soil. We also assess the changes in the annual cycles in three major rivers located in different hydro-climatic regions. Results show that conclusions can be influenced by uncertainty in the RCP scenarios. Future scenarios project a gradual increase in temperature (up to 7 degrees C on average), whilst changes (both increase and decrease) in the long-term average precipitation and evapotranspiration are more severe at the end of the century. The potential change (increase and decrease) in runoff could reach 100% depending on the region and time horizon. Analysis of annual cycles for three selected regions showed that changes in discharge and evapotranspiration due to climate change vary between seasons, whereas the magnitude of change is dependent on the region's hydro-climatic gradient. Irrigation needs and the snow depth in the Himalayas are also affected.

  • 257. Pechlivanidis, Ilias G.
    et al.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Sharma, Devesh
    Sharma, K. C.
    Multi-Basin Modelling of Future Hydrological Fluxes in the Indian Subcontinent2016In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 8, no 5, p. 177-177Article in journal (Refereed)
    Abstract [en]

    The impact of climate change on the hydro-climatology of the Indian subcontinent is investigated by comparing statistics of current and projected future fluxes resulting from three RCP scenarios (RCP2.6, RCP4.5, and RCP8.5). Climate projections from the CORDEX-South Asia framework have been bias-corrected using the Distribution-Based Scaling (DBS) method and used to force the HYPE hydrological model to generate projections of evapotranspiration, runoff, soil moisture deficit, snow depth, and applied irrigation water to soil. We also assess the changes in the annual cycles in three major rivers located in different hydro-climatic regions. Results show that conclusions can be influenced by uncertainty in the RCP scenarios. Future scenarios project a gradual increase in temperature (up to 7 degrees C on average), whilst changes (both increase and decrease) in the long-term average precipitation and evapotranspiration are more severe at the end of the century. The potential change (increase and decrease) in runoff could reach 100% depending on the region and time horizon. Analysis of annual cycles for three selected regions showed that changes in discharge and evapotranspiration due to climate change vary between seasons, whereas the magnitude of change is dependent on the region's hydro-climatic gradient. Irrigation needs and the snow depth in the Himalayas are also affected.

  • 258.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Gupta, H.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    An Information Theory Approach to Identifying a Representative Subset of Hydro-Climatic Simulations for Impact Modeling Studies2018In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 54, no 8, p. 5422-5435Article in journal (Refereed)
  • 259.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Jackson, B.
    McMillan, H.
    Gupta, H.
    Use of an entropy-based metric in multiobjective calibration to improve model performance2014In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 50, no 10, p. 8066-8083Article in journal (Refereed)
    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

  • 260.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Jackson, Bethanna
    Mcmillan, Hilary
    Gupta, Hoshin V.
    Robust informational entropy-based descriptors of flow in catchment hydrology2016In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 61, no 1, p. 1-18Article in journal (Refereed)
    Abstract [en]

    This paper explores the use of entropy-based measures in catchment hydrology, and provides an importance-weighted numerical descriptor of the flow-duration curve. Although entropy theory is being applied in a wide spectrum of areas (including environmental and water resources), artefacts arising from the discrete, under-sampled and uncertain nature of hydrological data are rarely acknowledged, and have not been adequately explored. Here, we examine challenges to extracting hydrologically meaningful entropy measures from a flow signal; the effect of binning resolution on calculation of entropy is investigated, along with artefacts caused by (1) emphasis of information theoretic measures towards flow ranges having more data (statistically dominant information), and (2) effects of discharge measurement truncation errors. We introduce an importance-weighted entropy-based measure to counter the tendency of common binning approaches to over-emphasise information contained in the low flows which dominate the record. The measure uses a novel binning method, and overcomes artefacts due to data resolution and under-sampling. Our analysis reveals a fundamental problem with the extraction of information at high flows, due to the lack of statistically significant samples in this range. By separating the flow-duration curve into segments, our approach constrains the computed entropy to better respect distributional properties over the data range. When used as an objective function for model calibration, this approach constrains high flow predictions, as well as the commonly used Nash-Sutcliffe efficiency, but provides much better predictions of low flow behaviour.

  • 261.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    McIntyre, N.
    Wheater, H. S.
    The significance of spatial variability of rainfall on simulated runoff: an evaluation based on the Upper Lee catchment, UK2017In: Hydrology Research, ISSN 1998-9563, E-ISSN 2224-7955, Vol. 48, no 4, p. 1118-1130Article in journal (Refereed)
  • 262.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Sharma, D.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Sharma, K. C.
    ASSESSMENT OF THE CLIMATE CHANGE IMPACTS ON THE WATER RESOURCES OF THE LUNI REGION, INDIA2015In: GLOBAL NEST JOURNAL, ISSN 1790-7632, Vol. 17, no 1, p. 29-40Article in journal (Refereed)
    Abstract [en]

    Climate change is expected to have a strong impact on water resources at the local, regional and global scales. In this study, the impact of climate change on the hydro-climatology of the Luni region, India, is investigated by comparing statistics of current and projected future fluxes resulting from three representative concentration pathways (RCP2.6, RCP4.5, and RCP8.5). The use of different scenarios allows for the estimation of uncertainty of future impacts. The projections are based on the CORDEX-South Asia framework and are bias-corrected using the DBS method before being entered into the HYPE (HYdrological Predictions for the Environment) hydrological model to generate predictions of runoff, evapotranspiration, soil moisture deficit, and applied irrigation water to soil. Overall, the high uncertainty in the climate projections is propagated in the impact model, and as a result the spatiotemporal distribution of change is subject to the climate change scenario. In general, for all scenarios, results show a -20 to +20% change in the long-term average precipitation and evapotranspiration, whereas more pronounced impacts are expected for runoff (-40 to +40% change). Climate change can also affect other hydro-climatic components, however, at a lower impact. Finally, the flow dynamics in the Luni River are substantially affected in terms of shape and magnitude.

  • 263.
    Pers, Charlotta
    SMHI, Research Department, Hydrology.
    BIOLA - Biogeochemical Lake Model Manual2003Report (Other academic)
  • 264.
    Pers, Charlotta
    SMHI, Research Department, Hydrology.
    HBV-NP Model Manual2007Report (Other academic)
  • 265.
    Pers, Charlotta
    SMHI, Research Department, Hydrology.
    Model description of BIOLA - a biogeochemical lake model2002Report (Other academic)
    Abstract [en]

    The biogeochemical lake model BIOLA was developed to be used for eutrophication studies in

    Sweden

    . Eutrophication is a threat for lakes in populated areas, and this model was developed to be

    a tool for managing lakes suffering from eutrophication. There are several measures that can be

    taken to reduce eutrophication. When considering different measures simulations of their effects,

    with models such as BIOLA, can contribute with information.

    The model is a biogeochemical lake module coupled to a one-dimensional hydrodynamic model.

    The model simulates the continuous change of lake stratification and water quality due to weather,

    inflow

    , outflow and biogeochemical processes in the lake and in the sediments. It simulates changes

    over time in nutrient and biological state at different depths. The most important variables simulated

    by the model are inorganic nutrients and phytoplankton in the water. Other variables include

    nutrients and organic matter in the sediments.

    The model has shown to be able to simulate changing nutrient and plankton dynamics. The result

    from three studied lakes are reviewed.

  • 266.
    Pers, Charlotta
    SMHI, Research Department, Hydrology.
    Modeling the response of eutrophication control measures in a Swedish lake2005In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, no 7, p. 552-558Article in journal (Refereed)
    Abstract [en]

    The response of a biogeochemical lake model (BIOLA) to different eutrophication management actions has been studied in a eutrophic lake. Management actions included in the study were nutrient load reduction, sediment manipulation, biomanipulation, and herbicide application. The model was used to simulate nutrient and biomass concentrations in the lake during the 1990s. During the same period, management scenarios were also simulated. Several ecological parameters were calibrated to better simulate the behavior of the chosen lake, but there were still some difficulties with phosphate. This indicated that further model development is necessary. The most favorable development within the lake was found for scenarios with nutrient load reduction and biomanipulation through planktivorous fish reduction. Reducing both the nitrogen and phosphorus loads had a greater effect on the lake's water quality than simply reducing just one of the nutrients.

  • 267.
    Pers, Charlotta
    et al.
    SMHI, Research Department, Hydrology.
    Persson, I
    Simulation of a biogeochemical model in different lakes2003In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 34, no 5, p. 543-558Article in journal (Refereed)
    Abstract [en]

    Eutrophication, caused by nutrients leached from soil and emitted from point sources, is a well-known problem in many Swedish lakes. There are several countermeasures that can be used to reduce eutrophication. A model that can simulate the biogeochemical response to different management scenarios may help with nutrient reducing strategies. Results from applications with such a model to different types of lakes are presented in this paper. The most important variables simulated by the model are dissolved nutrient concentrations (nitrogen and phosphorus) and phytoplankton. Other variables include nitrogen fixating cyanobacteria, sediments, and zooplankton. In total, 14 state variables are simulated. Nutrients are supplied through tributaries, and the temperature and vertical mixing forced by meteorological input. The model is able to simulate effects of changing nutrients and plankton dynamics. It is promising as an instrument for evaluating various measures to improve water quality in lakes. However, for the lakes the model has been applied to, the model has been calibrated to available observations. Non-monitored lakes could also be interesting to simulate, therefore the parameters of the model set-ups are discussed in this paper.

  • 268.
    Pers, Charlotta
    et al.
    SMHI, Research Department, Hydrology.
    Rahm, Lars
    SMHI, Research Department, Oceanography.
    Jonsson, A
    Bergstrom, A K
    Jansson, M
    Modelling dissolved organic carbon turnover in humic Lake Ortrasket, Sweden2001In: Environmental Modelling and Assessment, ISSN 1420-2026, E-ISSN 1573-2967, Vol. 6, no 3, p. 159-172Article in journal (Refereed)
    Abstract [en]

    The organic carbon balance of a lake with high input of allochthonous organic carbon is modelled integrating physical, chemical and biological processes. The physical model captures the behaviour of real thermal stratification in the lake for different flow situations during the period 1993-1997. The dissolved organic carbon model is based on simulated trajectories of water parcels. By tracking parcels, account is kept of environmental factors such as temperature and radiation as well as DOC quality for each parcel, The DOC concentration shows seasonal variations primarily dependent on inflow. The organic matter degradation (bacterial- and photodegradation) in the lake amounts to 1.5-2.5 mg C l(-1) yr(-1), where photooxidation is responsible for approximately 10%. The estimated DIC production in the lake is large compared to sediment mineralisation and primary production. The main conclusion is that the model with the selected parameterisations of the degradation processes reasonably well describes the DOC dynamics in a forest lake.

  • 269.
    Pers, Charlotta
    et al.
    SMHI, Research Department, Hydrology.
    Temnerud, Johan
    SMHI, Research Department, Hydrology.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Modelling water, nutrients, and organic carbon in forested catchments: a HYPE application2016In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, no 18, p. 3252-3273Article in journal (Refereed)
  • 270. Persson, M
    et al.
    Haridy, S
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Wendt, J
    Solute transport dynamics by high-resolution dye tracer experiments - Image analysis and time moments2005In: Vadose Zone Journal, ISSN 1539-1663, E-ISSN 1539-1663, Vol. 4, no 3, p. 856-865Article in journal (Refereed)
    Abstract [en]

    Accurate measurements of solute concentration are needed to conduct studies of solute transport process in unsaturated soil. In this paper we present a method of obtaining accurate measurements in and space using dye infiltration and image analysis. The soil color was related to the dye concentration in the soil (C-s) using 74 small calibration samples. The overall root mean square error (RMSE) 0.057 g dm(-3), however, for C-s < 0.75 g dm(-3), the RMSE was only 0.032 g dm(-3). Variability of the concentration estimates at the pixel scale could be reduced by using an average filter. We used the calibration relationship during four infiltration experiments in a 0.95 by 0.975 m large Plexiglas Hele-Shaw cell to calculate dye concentration patterns. Using the first and second order time moments, the dispersivity lambda was calculated for nine different artificial column widths, from 0.0014 (local-scale) to 0.72 m (meso-scale). The horizontally averaged lambda proved to be identical for column widths from 0.0014 to 0.045 m. For larger scales, lambda gradually increased. We noticed that the two experiments with higher flow (1 and 2) and the two experiments with lower flow (3 and 4) showed an almost identical variation of meso-scale lambda with depth. We concluded that above a specific critical value of theta (similar to 0.22 m(3) m(-3)), solute mixing is enhanced, leading to a lower lambda, and that solute transport can be described as a convective-dispersive process. When theta is lower than this critical level, part of the porosity is deactivated and mixing between individual stream tubes decreases, which implies that transport then occurs as a stochastic-convective process.

  • 271. Persson, Magnus
    et al.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Scaling analyses of high-resolution dye tracer experiments2008In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 53, no 6, p. 1286-1299Article in journal (Refereed)
    Abstract [en]

    Four unsaturated solute transport experiments with different water fluxes were conducted in a Hele-Shaw cell filled with uniform sand. The transport of the dye tracer used was recorded with a camera and the dye concentration was calculated using image analysis. The concentrations fields were analysed in terms of time moments and converted into vertical solute transport velocity V. Both mean value and standard deviation of V increased with water flux. The autocorrelation function exhibited a linear decrease for short lags. The pronounced variability of V suggested a description in terms of scaling properties, and a scaling regime was indeed found from the resolution 1.8 mm up to almost 0.1 m. The upper limit corresponds roughly to a characteristic scale of fingering structures seen in the dye concentration images. Indications of a second scaling regime at larger scales were found. In the small-scale scaling regime, the power spectrum exponent beta was generally slightly below 1 and the intermittency parameter C(1) was on average 0.00025. The moment scaling K(q) functions were convex, implying a multiscaling process.

  • 272. Persson, Magnus
    et al.
    Selim, Tarek
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Groundwater contamination risks from conservative point source pollutants in a future climate2019In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 64, no 13, p. 1659-1671Article in journal (Refereed)
  • 273.
    Pettersson, Anna
    et al.
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Johansson, Barbro
    SMHI, Professional Services.
    Nitrogen concentrations simulated with HBV-N: New response function and calibration strategy - Paper presented at the Nordic Hydrological Conference (Uppsala, Sweden June, 2000)2001In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 32, no 3, p. 227-248Article in journal (Refereed)
    Abstract [en]

    HBV-N is a conceptual process-based model for simulation of transformation and transport of nitrogen on the catchment scale. This paper presents further development with focus on the response function and calibration procedures. Evaluation of the model routines was made in 12 test basins in southern Sweden (without or with only few lakes). Previous versions of HBV-N included a HBV version with a single reservoir in the response function. The presented results show that both nitrogen concentrations and water discharge simulations improved when a second reservoir was introduced. The two-reservoir model was found to be more well-posed for description of residence-times and flow paths. On average, this resulted in an increase in explained variance (R-2) for nitrogen concentrations by 0.3. Multiple-response split-sample calibration was found to further improve the model performance and reliability. In previous applications HBV-N has been applied by using single-response calibration. However, simultaneous calibration of water discharge and nitrogen improved the R2 for nitrogen concentrations by about 0.1 (range 0.02-0.25), but did not affect the simulation of water discharge. This new calibration strategy forces the hydrological parameters to a new optimum, and reduces the level of uncertainty for both hydrochemical and hydrological modelling.

  • 274.
    Pimentel, Rafael
    et al.
    SMHI, Research Department, Hydrology.
    Herrero, Javier
    Polo, Maria Jose
    Quantifying Snow Cover Distribution in Semiarid Regions Combining Satellite and Terrestrial Imagery2017In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 9, no 10, article id 995Article in journal (Refereed)
  • 275.
    Pimentel, Rafael
    et al.
    SMHI, Research Department, Hydrology.
    Herrero, Javier
    Polo, Maria Jose
    Subgrid parameterization of snow distribution at a Mediterranean site using terrestrial photography2017In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 21, no 2, p. 805-820Article in journal (Refereed)
  • 276. Pisinaras, Vassilios
    et al.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Gemitzi, Alexandra
    Conceptualizing and assessing the effects of installation and operation of photovoltaic power plants on major hydrologic budget constituents2014In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 493, p. 239-250Article in journal (Refereed)
    Abstract [en]

    This study addresses the effects of land use change from agricultural to photovoltaic parks (PVPs) on the hydrology of an area. Although many environmental effects have been identified and analyzed, only minor attention has been given to the hydrologic effects of the installation and operation of PVPs. The effects of current PVP installation and operation practices on major hydrologic budget constituents (surface runoff, evapotranspiration and percolation) were identified, conceptualized, quantified and simulated using SWAT model. Vosvozis river basin located in north Greece was selected as a test site. Additionally, long-term effects were simulated using dynamically downscaled climate projections by a Regional Climate Model (RCM) driven by 5 different General Circulation Models (GCMs) for the period 2011-2100. Results indicate that surface runoff and percolation potential are significantly increased at the local scale and have to be considered during PVP siting, especially when sensitive and protected ecosystems are involved. (C) 2014 Elsevier B.V. All rights reserved.

  • 277. Pugliese, Alessio
    et al.
    Persiano, Simone
    Bagli, Stefano
    Mazzoli, Paolo
    Parajka, Juraj
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Capell, Réne
    SMHI, Research Department, Hydrology.
    Montanari, Alberto
    Bloeschl, Guenter
    Castellarin, Attilio
    A geostatistical data-assimilation technique for enhancing macro-scale rainfall-runoff simulations2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, no 9, p. 4633-4648Article in journal (Refereed)
  • 278. Raschke, E
    et al.
    Meywerk, J
    Warrach, K
    Andrae, Ulf
    SMHI, Research Department, Meteorology.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Beyrich, F
    Bosveld, F
    Bumke, K
    Fortelius, C
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Gryning, S E
    Halldin, S
    Hasse, L
    Heikinheimo, M
    Isemer, H J
    Jacob, D
    SMHI.
    Jauja, I
    Karlsson, Karl-Göran
    SMHI, Research Department, Atmospheric remote sensing.
    Keevallik, S
    Koistinen, J
    van Lammeren, A
    Lass, U
    Launianen, J
    Lehmann, A
    Liljebladh, B
    Lobmeyr, M
    Matthaus, W
    Mengelkamp, T
    Michelson, Daniel
    SMHI, Core Services.
    Napiorkowski, J
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    Piechura, J
    Rockel, B
    Rubel, F
    Ruprecht, E
    Smedman, A S
    Stigebrandt, A
    The Baltic Sea Experiment (BALTEX): A European contribution to the investigation of the energy and water cycle over a large drainage basin2001In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 82, no 11, p. 2389-2413Article, review/survey (Refereed)
    Abstract [en]

    The Baltic Sea Experiment (BALTEX) is one of the five continental-scale experiments of the Global Energy and Water Cycle Experiment (GEWEX). More than 50 research groups from 14 European countries are participating in this project to measure and model the energy and water cycle over the large drainage basin of the Baltic Sea in northern Europe. BALTEX aims to provide a better understanding of the processes of the climate system and to improve and to validate the water cycle in regional numerical models for weather forecasting and climate studies. A major effort is undertaken to couple interactively the atmosphere with the vegetated continental surfaces and the Baltic Sea including its sea ice. The intensive observational and modeling phase BRIDGE, which is a contribution to the Coordinated Enhanced Observing Period of GEWEX, will provide enhanced datasets for the period October 1999-February 2002 to validate numerical models and satellite products. Major achievements have been obtained in an improved understanding of related exchange processes. For the first time an interactive atmosphere-ocean-land surface model for the Baltic Sea was tested. This paper reports on major activities and some results.

  • 279. Raty, Olle
    et al.
    Raisanen, Jouni
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Intercomparison of Univariate and Joint Bias Correction Methods in Changing Climate From a Hydrological Perspective2018In: Climate, ISSN 2053-7565, E-ISSN 2225-1154, Vol. 6, no 2, article id 33Article in journal (Refereed)
  • 280. Raty, Olle
    et al.
    Virta, Hanna
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Regional climate model and model output statistics method uncertainties and the effect of temperature and precipitation on future river discharges in Scandinavia2017In: Hydrology Research, ISSN 1998-9563, E-ISSN 2224-7955, Vol. 48, no 5, p. 1363-1377Article in journal (Refereed)
  • 281. Reckermann, Marcus
    et al.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Omstedt, Anders
    Göteborgs Universitet.
    von Storch, Hans
    Keevallik, Sirje
    Schneider, Bernd
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Huenicke, Birgit
    BALTEX-an interdisciplinary research network for the Baltic Sea region2011In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 6, no 4, article id 045205Article in journal (Refereed)
    Abstract [en]

    BALTEX is an environmental research network dealing with the Earth system of the entire Baltic Sea drainage basin. Important elements include the water and energy cycle, climate variability and change, water management and extreme events, and related impacts on biogeochemical cycles. BALTEX was founded in 1993 as a GEWEX continental-scale experiment and is currently in its second 10 yr phase. Phase I (1993-2002) was primarily dedicated to hydrological, meteorological and oceanographic processes in the Baltic Sea drainage basin, hence mostly dealt with the physical aspects of the system. Scientific focus was on the hydrological cycle and the exchange of energy between the atmosphere, the Baltic Sea and the surface of its catchment. The BALTEX study area was hydrologically defined as the Baltic Sea drainage basin. The second 10 yr phase of BALTEX (Phase II: 2003-12) has strengthened regional climate research, water management issues, biogeochemical cycles and overarching efforts to reach out to stakeholders and decision makers, as well as to foster communication and education. Achievements of BALTEX Phase II have been the establishment of an assessment report of regional climate change and its impacts on the Baltic Sea basin (from hydrological to biological and socio-economic), the further development of regional physical climate models and the integration of biogeochemical and ecosystem models. BALTEX features a strong infrastructure, with an international secretariat and a publication series, and organizes various workshops and conferences. This article gives an overview of the BALTEX programme, with an emphasis on Phase II, with some examples from BALTEX-related research.

  • 282. Refsgaard, Jens Christian
    et al.
    Hansen, Anne L.
    Hojberg, Anker L.
    Olesen, Jorgen E.
    Hashemi, Fatemeh
    Wachniew, Przemyslaw
    Worman, Anders
    Bartosova, Alena
    SMHI, Research Department, Hydrology.
    Stelljes, Nico
    Chubarenko, Boris
    Spatially differentiated regulation: Can it save the Baltic Sea from excessive N-loads?2019In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 48, no 11, p. 1278-1289Article in journal (Refereed)
  • 283.
    Riml, Joakim
    et al.
    SMHI, Research Department, Hydrology.
    Worman, Anders
    Response functions for in-stream solute transport in river networks2011In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 47, article id W06502Article in journal (Refereed)
    Abstract [en]

    This paper analyzes the effects of different hydrological mechanisms on the solute response in watershed stream networks. Important processes are due to the hydraulic and chemical retention of reactive solutes in transient storage zones and the cumulative consequences of these processes from a single transport pathway as well as from the network of transport pathways. Temporal moments are derived for a distributed stream network and for a compartment-in-series model. The temporal moments are evaluated and are utilized to derive formal expressions for translating the network parameters into compartmental model parameters. The analysis reveals that in addition to the hydraulic and chemical retention processes, the morphological and topological properties of a watershed have a distinct impact on the central temporal moments in terms of averaging of the solute load weighted distances as well as the transport parameters over the network. Kinetic (rate-limited) transient storage affects second-order and higher central temporal moments and thus has a secondary effect on the parameterization of compartmental models. Additional considerable contributions to all temporal moments are introduced when parameter variability along transport pathways is considered. The paper demonstrates an improved model outcome for phosphorus transport in a small Swedish watershed by accounting for the overall network effects when parameterizing a compartment-in-series model.

  • 284.
    Riml, Joakim
    et al.
    SMHI, Research Department, Hydrology.
    Worman, Anders
    Kunkel, Uwe
    Radke, Michael
    Evaluating the fate of six common pharmaceuticals using a reactive transport model: Insights from a stream tracer test2013In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 458, p. 344-354Article in journal (Refereed)
    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.

  • 285.
    Rodriquez, Mercedes
    et al.
    SMHI.
    Johansson, Barbro
    SMHI, Professional Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Planos, Eduardo
    INRH Instituto Nacional de Recursos Hidraulicos.
    Remont, Alfredo
    INRH Instituto Nacional de Recursos Hidraulicos.
    Aplicacion del modelo HBV a la cuenca del Río Cauto en Cuba1991Report (Other academic)
    Abstract [en]

    The work deseribed in this report, was done in eollaboration between the Swedish Meteorological and Hydrologieal Institute (SMID) and the Instituto Nacional de Reeursos Hidraulieos de Cuba (INRH), with financial support from the Swedish Ageney for Teehnieal and Eeonomie Cooperation (BITS). The projeet also reeeived aetive assistanee from the Cuban State Committee for Economie Collaboration (CECE). The main objetive of the projeet was the applieation of the HBV model to the Cauto river basin in eastem Cuba, in order to - foreeast the inflow volwne to the reservoirs located in the basin and - eontribute to the rational use of water in the reservoirs.

  • 286. Roudier, Philippe
    et al.
    Andersson, Jafet
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Feyen, Luc
    Greuell, Wouter
    Ludwig, Fulco
    Projections of future floods and hydrological droughts in Europe under a+2 degrees C global warming2016In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 135, no 2, p. 341-355Article in journal (Refereed)
  • 287. Ruete, Alejandro
    et al.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Stenseth, Nils Chr.
    Snall, Tord
    Disentangling effects of uncertainties on population projections: climate change impact on an epixylic bryophyte2012In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 279, no 1740, p. 3098-3105Article in journal (Refereed)
    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.

  • 288.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Källén, Erland
    Meterologi.
    Moen, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Rodhe, J.
    SMHI.
    Tjernström, M
    SWECLIM - The First Three Years2000Report (Other academic)
    Abstract [en]

    The Swedish Regional Clirnate Modeling Program (SWECLIM) is a 6-year national research effort with the airn of providing the Swedish society with more detailed regional climate scenarios than typically available from international global clirnate rnodel simulations. The background is the perceived further enhancernent of the greenhouse effect that is projected to lead to global warming and other changes m the clirnate systern. SWECLIM provides users within governmental organizations, businesses, political decision-rnaking, as well as media and the general public with expertise and synthesis of clirnate change issues, science, results and the detailed regional climate scenarios, to further the understanding of the future changes, to facilitate planning and realization of rnitigation and/or adaptation measures. This requires developrnent and use of regionalization techniques, regional rnodeling tools and other studies of the relevant regional processes and collected data. Apart from hydrological interpretation done of the clirnate scenarios, SWECLIM does not perfonn irnpact studies. Additional concretization of the clirnate scenarios by externa! groups, who possess branch-specific irnpact assessrnent expertise, is supported and encouraged by SWECLIM.

    This report describes the background of the SWECLIM-prograrn, the work undertaken during program phase 1,l asting from 1997 to June 2000. The model developrnent, the prepared regional climate and water resources scenarios, results from statistical downscaling and basic process studies and data analyses, as well as the interaction with users and media are covered. Finally, a brief introduction to the program phase 2 plans are provided.

  • 289.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Persson, Gunn
    SMHI, Professional Services.
    Ressner, Elisabet
    SMHI.
    Anpassning till klimatförändringar: Kartläggning av arbete med sårbarhetsanalyser, anpassningsbehov och anpassningsåtgärder i Sverige till framtida klimatförändring2005Report (Other academic)
    Abstract [sv]

    Denna rapport är resultatet av ett uppdrag från Naturvårdsverket till SMHI (NV dnr 235-5045-04H k), som genomförts under hösten 2004. Syftet är att få en överblick över vilka aktörer som för närvarande är aktiva med att analysera eventuella effekter på samhället och att kartlägga anpassningsbehov. Avsikten är också att få en bild av planerade eller redan genomförda insatser och skyddsåtgärder på grund av en befarad klimatförändring. Kartläggningen omfattar ett flertal svenska myndigheter, företag samt ett antal relevanta bransch- och intresseorganisationer och forskningsfinansiärer.I rapporten redovisas även översiktligt de hinder i anpassningsarbetet som identifierats samt önskemål om förbättrat beslutsunderlag.Slutligen förs en översiktlig diskussion om tänkbara sektoriella effekter avav klimatförändringen, baserad på tidigare avnämarkontakter och forskningsinsatser inom området

  • 290.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Persson, Gunn
    SMHI, Professional Services.
    Rodhe, J
    Tjernstrom, M
    The Swedish Regional Climate Modelling Programme, SWECLIM: A review2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, no 4-5, p. 176-182Article, review/survey (Refereed)
    Abstract [en]

    The Swedish Regional Climate Modelling Programme, SWECLIM, was a 6.5-year national research network for regional climate modeling, regional climate change projections and hydrological impact assessment and information to a wide range of stakeholders. Most of the program activities focussed on the regional climate system of Northern Europe. This led to the establishment of an advanced, coupled atmosphere-ocean-hydrology regional climate model system, a suite of regional climate change projections and progress on relevant data and process studies. These were, in turn, used for information and educational purposes, as a starting point for impact analyses on different societal sectors and provided contributions also to international climate research.

  • 291. Samaniego, L.
    et al.
    Kumar, R.
    Breuer, L.
    Chamorro, A.
    Floerke, M.
    Pechlivanidis, Ilias
    SMHI, Research Department, Hydrology.
    Schaefer, D.
    Shah, H.
    Vetter, T.
    Wortmann, M.
    Zeng, X.
    Propagation of forcing and model uncertainties on to hydrological drought characteristics in a multi-model century-long experiment in large river basins2017In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 141, no 3, p. 435-449Article in journal (Refereed)
  • 292.
    Sandén, Per
    SMHI, Research Department, Hydrology.
    ESTIMATION AND SIMULATION OF METAL MASS-TRANSPORT IN AN OLD MINING AREA1991In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 57-8, p. 387-397Article in journal (Refereed)
    Abstract [en]

    In a watershed with an old mine tailings deposit, mass transport of Cu, Zn and Cd was studied. An extensive sampling program and the use of the PULSE model for the simulation of water flow made it feasible to simulate and compare the dynamics of metal transport at different sites in the study area. Close to the tailings deposit, the weathering rate in the deposit had a large impact on the dynamics of the mass transport, and interannual variation in mass transport was considerably lower than the variation in runoff. Further downstream, the mass transport was almost exclusively determined by the water flow and, thus far unidentified, mechanisms maintained fairly constant metal concentrations in the stream water. The usefulness of the PULSE model for simulating metal concentrations may still be questioned. However, it is noteworthy that a hydrochemical model based on a fairly simple description of the mixing of water from different sources and a very simple pH dependence of the concentration of metals, at least semi-quantitatively, can reproduce the dynamics of metal concentrations and mass transport of metals.

  • 293.
    Sandén, Per
    et al.
    SMHI, Research Department, Hydrology.
    Rahm, Lars
    SMHI, Research Department, Oceanography.
    WULFF, F
    NONPARAMETRIC TREND TEST OF BALTIC SEA DATA1991In: Environmetrics, ISSN 1180-4009, E-ISSN 1099-095X, Vol. 2, no 3, p. 263-278Article in journal (Refereed)
    Abstract [en]

    The recently reported tendencies toward decreasing total amounts of silicate in the Baltic Sea are investigated by use of non-parametric trend analysis. The period 1968-1986 showed significant falling trends in surface waters from the whole system. The deepest parts of the Baltic proper did in contrast reveal strong increasing trends. These trends are more pronounced during the latter part of the analysis period which is characterized by stagnant conditions in the Baltic proper. These conditions have been prevailing since the major inflow in 1976. The causes of the observed changes are unclear. The increased load of nutrients and accompanying increase in primary production is, however, one factor. Another is coupled to the stagnation conditions of the Baltic Proper.

  • 294. Schoumans, O. F.
    et al.
    Silgram, M.
    Walvoort, D. J. J.
    Groenendijk, P.
    Bouraoui, F.
    Andersen, H. E.
    Lo Porto, A.
    Reisser, H.
    Le Gall, G.
    Anthony, S.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Johnsson, H.
    Panagopoulos, Y.
    Mimikou, M.
    Zweynert, U.
    Behrendt, H.
    Barr, A.
    Evaluation of the difference of eight model applications to assess diffuse annual nutrient losses from agricultural land2009In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 11, no 3, p. 540-553Article in journal (Refereed)
    Abstract [en]

    The capability of eight nutrient models to predict annual nutrient losses (nitrogen and phosphorus) at catchment scale have been studied in the EUROHARP project. The methodologies involved in these models differ profoundly in their complexity, level of process representation and data requirements. This evaluation is focused on model performance in three core catchments: the Vansjo-Hobol (Norway), the Ouse ( Yorkshire, UK) and the Enza (Italy). These three different model applications have been evaluated by comparing calculated annual nutrient loads (total N or nitrate and total P), based on observed flow and total nitrogen or nitrate and total phosphorus concentrations, and the annual nutrient loads that were simulated by the eight nutrient models. Four statistics have been applied for this purpose: the root mean squared error (RMSE), the mean absolute error (MAE), the mean error (ME), and Nash-Sutcliffe's model efficiency (NS). The results show that all model approaches can predict the calculated annual discharges. Depending on the observed statistics ( RMSE, MAE, ME and NS) the scores of the model application differed, therefore no overall 'best model' could be identified. Although the water and nutrient loads from (sub) catchments can be predicted, the modelled pathways of nutrients within agricultural land and the nutrient losses to surface waters from agricultural land vary among the catchments and among those model approaches which are able to make this distinction.

  • 295. Selim, Tarek
    et al.
    Persson, Magnus
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Impact of spatial rainfall resolution on point-source solute transport modelling2017In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 62, no 16, p. 2587-2596Article in journal (Refereed)
  • 296. Silgram, M.
    et al.
    Anthony, S. G.
    Collins, A. L.
    Stromqvist, J.
    Bouraoui, F.
    Schoumans, O.
    Lo Porto, A.
    Groenendijk, P.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Mimikou, M.
    Johnsson, H.
    Evaluation of diffuse pollution model applications in EUROHARP catchments with limited data2009In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 11, no 3, p. 554-571Article in journal (Refereed)
    Abstract [en]

    The application of diffuse pollution models included in EUROHARP encompassed varying levels of parameterisation and approaches to the preparation of input data depending on the model and modelling team involved. Modellers consistently faced important decisions in relation to data interpretation, especially in those catchments with unfamiliar physical or climatic characteristics, where catchment conditions were beyond the range for which a particular model was originally developed, or where only limited input data were available. In addition to a broad discussion of data issues, this paper compares the performance of the four sub-annual output models tested in EUROHARP (EveNFlow, NL-CAT, SWAT and TRK) in three test catchments without the modelling teams having sight of measured flow and nitrate concentration data. Model performance in this "blind test" indicate that the range of predictions generated by any individual models pre and post calibration exceed the differences between the estimates yielded by all four models. Comparison of Analysis of Variance (ANOVA) statistics for simulated and observed flow, concentration and loads underscores the benefits of calibration for these intermediate and complex model formulations. Interpretation of input data (e. g. rainfall interpolation method and pedotransfer functions selected) appeared equally (or more) important than process representation. In the absence of calibration data, modeller unfamiliarity with a particular catchment and its environmental processes sometimes resulted in questionable assumptions and input errors which highlight the problems facing modellers charged with implementing policies under the Water Framework Directive (2000/60/EC) in poorly monitored catchments. Catchment data owners and modellers must therefore work more closely given that the output from diffuse pollution models is clearly modeller-limited as well as model-limited.

  • 297. Silgram, M.
    et al.
    Schoumans, O. F.
    Walvoort, D. J. J.
    Anthony, S. G.
    Groenendijk, P.
    Stromqvist, J.
    Bouraoui, F.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Kapetanaki, M.
    Lo Porto, A.
    Martensson, K.
    Subannual models for catchment management: evaluating model performance on three European catchments2009In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 11, no 3, p. 526-539Article in journal (Refereed)
    Abstract [en]

    Models' abilities to predict nutrient losses at subannual timesteps is highly significant for evaluating policy measures, as it enables trends and the frequency of exceedance of water quality thresholds to be predicted. Subannual predictions also permit assessments of seasonality in nutrient concentrations, which are necessary to determine susceptibility to eutrophic conditions and the impact of management practices on water quality. Predictions of subannual concentrations are pertinent to EC Directives, whereas load estimates are relevant to the 50% target reduction in nutrient loading to the maritime area under OSPAR. This article considers the ability of four models ( ranging from conceptual to fully mechanistic), to predict river flows, concentrations and loads of nitrogen and phosphorus on a subannual basis in catchments in Norway, England, and Italy. Results demonstrate that model performance deemed satisfactory on an annual basis may conceal considerable divergence in performance when scrutinised on a weekly or monthly basis. In most cases the four models performed satisfactorily, and mismatches between measurements and model predictions were primarily ascribed to the limitations in input data ( soils in the Norwegian catchment; weather in the Italian catchment). However, results identified limitations in model conceptualisation associated with the damping and lagging effect of a large lake leading to contrasts in model performance upstream and downstream of this feature in the Norwegian catchment. For SWAT applied to the Norwegian catchment, although flow predictions were reasonable, the large number of parameters requiring identification, and the lack of familiarity with this environment, led to poor predictions of river nutrient concentrations.

  • 298. Soares, Ana R. A.
    et al.
    Lapierre, Jean-Francois
    Selvam, Balathandayuthabani P.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Berggren, Martin
    Controls on Dissolved Organic Carbon Bioreactivity in River Systems2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 14897Article in journal (Refereed)
  • 299. Sponseller, Ryan A.
    et al.
    Temnerud, Johan
    SMHI, Research Department, Hydrology.
    Bishop, Kevin
    Laudon, Hjalmar
    Patterns and drivers of riverine nitrogen (N) across alpine, subarctic, and boreal Sweden2014In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 120, no 1-3, p. 105-120Article in journal (Refereed)
    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.

  • 300.
    Strombäck, Lena
    et al.
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    The Importance of Open Data and Software for Large Scale Hydrological Modelling2013In: Open water Journal, Vol. 2, no 1, article id 32Article in journal (Refereed)
34567 251 - 300 of 346
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