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  • 301. Tjernström, M
    et al.
    Rummukainen, Markku
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    Rodhe, J.
    SMHI.
    Persson, Gunn
    SMHI, Affärsverksamhet.
    Klimatmodellering och klimatscenarier ur SWECLIMs perspektiv2003Rapport (Övrigt vetenskapligt)
  • 302. Tonderski, K S
    et al.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Modeling the impact of potential wetlands on phosphorus retention in a Swedish catchment2005Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, nr 7, s. 544-551Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In southern Sweden, wetlands are constructed to remove nitrogen (N) in agricultural catchments. The possible effects of such wetlands on riverine phosphorus (P) were also estimated using input-output data from three well-monitored wetlands. This was done to formulate a simple model for removal of P that is dependent on inflow characteristics. Next, the N- and P-reducing effects of wetlands were modeled on a catchment scale (1900 km 2) using the HBV-NP model and various assumptions about the wetland area and location. All three wetlands functioned as sinks for total P (tot-P) and for total suspended solids (TSS) with a removal of 10% to 31% and 28% to 50%, respectively. Mean P-removal rates of 17-49 kg ha(-1) yr(-1) were well simulated with the model. Catchment scale simulations indicated that wetlands were more efficient (in percentage of load) as traps for P than for N and that this may motivate the construction of wetlands for P removal far upstream from the catchment outlet.

  • 303. Tonderski, Karin
    et al.
    Andersson, Lotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    St Cyr, Rasmus
    Schoenberg, Ronny
    Taubald, Heinrich
    Assessing the use of delta O-18 in phosphate as a tracer for catchment phosphorus sources2017Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 607, s. 1-10Artikel i tidskrift (Refereegranskat)
  • 304. van Vliet, Michelle T. H.
    et al.
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Strombäck, Lena
    SMHI, Forskningsavdelningen, Hydrologi.
    Capell, Réne
    SMHI, Forskningsavdelningen, Hydrologi.
    Ludwig, Fulco
    European scale climate information services for water use sectors2015Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 528, s. 503-513Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study demonstrates a climate information service for pan-European water use sectors that are vulnerable to climate change induced hydrological changes, including risk and safety (disaster preparedness), agriculture, energy (hydropower and cooling water use for thermoelectric power) and environment (water quality). To study the climate change impacts we used two different hydrological models forced with an ensemble of bias-corrected general circulation model (GCM) output for both the lowest (2.6) and highest (8.5) representative concentration pathways (RCP). Selected indicators of water related vulnerability for each sector were then calculated from the hydrological model results. Our results show a distinct north-south divide in terms of climate change impacts; in the south the water availability will reduce while in the north water availability will increase. Across different climate models precipitation and streamflow increase in northern Europe and decrease in southern Europe, but the latitude at which this change occurs varies depending on the GCM. Hydrological extremes are increasing over large parts of Europe. The agricultural sector will be affected by reduced water availability (in the south) and increased drought. Both streamflow and soil moistures droughts are projected to increase in most parts of Europe except in northern Scandinavia and the Alps. The energy sector will be affected by lower hydropower potential in most European countries and reduced cooling water availability due to higher water temperatures and reduced summer river flows. Our results show that in particular in the Mediterranean the pressures are high because of increasing drought which will have large impacts on both the agriculture and energy sectors. In France and Italy this is combined with increased flood hazards. Our results show important impacts of climate change on European water use sectors indicating a clear need for adaptation. (C) 2015 Published by Elsevier B.V.

  • 305. Venohr, M
    et al.
    Donohue, I
    Fogelberg, S
    SMHI.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Irvine, K
    Behrendt, H
    Nitrogen retention in a river system and the effects of river morphology and lakes2005Ingår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 51, nr 3-4, s. 19-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mean annual transfer (loss and retention) of nitrogen in a river system was estimated using a conceptual approach based on water surface area and runoff. Two different approaches for the calculation of water surface area were applied to determine riverine nitrogen retention in four European catchments, ranging between 860-14,000 km(2) in area, and differing considerably in the proportion and distribution of surface waters, specific runoff and specific nutrient emissions. The transfer rate was estimated sequentially as either the mean value for the total catchment, on a sub-catchment scale, or considering the distribution of water surface area within a sub-catchment. For the latter measure, nitrogen retention in larger lakes was calculated separately. Nitrogen emissions modelled with MONERIS and HBV-N were used to calculate nitrogen river loads and compare those with observed loads. Inclusion of the proportion of water area within a sub-catchment improved modelled results in catchment with large lakes in sub-catchments, but not where there was a homogenous distribution of surface waters among sub-catchments.

  • 306. Verhoeven, J T A
    et al.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Yin, C Q
    Hefting, M M
    Regional and global concerns over wetlands and water quality2006Ingår i: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 21, nr 2, s. 96-103Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Water quality in many stream catchments and river basins is severely impacted by nutrient enrichment as a result of agriculture. Water-resource managers worldwide are considering the potential role of riparian zones and floodplain wetlands in improving stream-water quality, as there is evidence at the site scale that such wetlands are efficient at removing nutrients from through-flowing water. However, recent studies have highlighted disadvantages of such use of wetlands, including emissions of greenhouse gases and losses of biodiversity that result from prolonged nutrient loading. Here, we discuss the water purification function of wetlands at the site and catchment scale and suggest ways in which these disadvantages could be overcome.

  • 307. Verma, Siddhartha
    et al.
    Bartosova, Alena
    SMHI, Forskningsavdelningen, Hydrologi.
    Markus, Momcilo
    Cooke, Richard
    Um, Myoung-Jin
    Park, Daeryong
    Quantifying the Role of Large Floods in Riverine Nutrient Loadings Using Linear Regression and Analysis of Covariance2018Ingår i: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 10, nr 8, artikel-id 2876Artikel i tidskrift (Refereegranskat)
  • 308. Verma, Siddhartha
    et al.
    Markus, Momcilo
    Bartosova, Alena
    SMHI, Forskningsavdelningen, Hydrologi.
    Cooke, Richard A.
    Intra-Annual Variability of Riverine Nutrient and Sediment Loadings Using Weighted Circular Statistics2018Ingår i: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 144, nr 3, artikel-id 04018010Artikel i tidskrift (Refereegranskat)
  • 309. Vesakoski, Jenni-Mari
    et al.
    Nylen, Tua
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Gustafsson, David
    SMHI, Forskningsavdelningen, Hydrologi.
    Isberg, Kristina
    SMHI, Forskningsavdelningen, Hydrologi.
    Holopainen, Markus
    Hyyppa, Juha
    Alho, Petteri
    Arctic Mackenzie Delta channel planform evolution during 1983-2013 utilising Landsat data and hydrological time series2017Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 31, nr 22, s. 3979-3995Artikel i tidskrift (Refereegranskat)
  • 310. Vetter, Tobias
    et al.
    Reinhardt, Julia
    Floerke, Martina
    van Griensven, Ann
    Hattermann, Fred
    Huang, Shaochun
    Koch, Hagen
    Pechlivanidis, Ilias
    SMHI, Forskningsavdelningen, Hydrologi.
    Ploetner, Stefan
    Seidou, Ousmane
    Su, Buda
    Vervoort, R. Willem
    Krysanova, Valentina
    Evaluation of sources of uncertainty in projected hydrological changes under climate change in 12 large-scale river basins2017Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 141, nr 3, s. 419-433Artikel i tidskrift (Refereegranskat)
  • 311. Viney, Neil R.
    et al.
    Bormann, H.
    Breuer, L.
    Bronstert, A.
    Croke, B. F. W.
    Frede, H.
    Graeff, T.
    Hubrechts, L.
    Huisman, J. A.
    Jakeman, A. J.
    Kite, G. W.
    Lanini, J.
    Leavesley, G.
    Lettenmaier, D. P.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Seibert, J.
    Sivapalan, M.
    Willems, P.
    Assessing the impact of land use change on hydrology by ensemble modelling (LUCHEM) II: Ensemble combinations and predictions2009Ingår i: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 32, nr 2, s. 147-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports on a project to compare predictions from a range of catchment models applied to a mesoscale river basin in central Germany and to assess various ensemble predictions of catchment streamflow. The models encompass a large range in inherent complexity and input requirements. In approximate order of decreasing complexity, they are DHSVM, MIKE-SHE, TOPLATS, WASIM-ETH, SWAT, PRMS, SLURP, HBV, LASCAM and IHACRES. The models are calibrated twice using different sets of input data. The two predictions from each model are then combined by simple averaging to produce a single-model ensemble. The 10 resulting single-model ensembles are combined in various ways to produce multi-model ensemble predictions. Both the single-model ensembles and the multi-model ensembles are shown to give predictions that are generally superior to those of their respective constituent models, both during a 7-year calibration period and a 9-year validation period. This occurs despite a considerable disparity in performance of the individual models. Even the weakest of models is shown to contribute useful information to the ensembles they are part of. The best model combination methods are a trimmed mean (constructed using the central four or six predictions each day) and a weighted mean ensemble (with weights calculated from calibration performance) that places relatively large weights on the better performing models. Conditional ensembles. in which separate model weights are used in different system states (e.g. summer and winter, high and low flows) generally yield little improvement over the weighted mean ensemble. However a conditional ensemble that discriminates between rising and receding flows shows moderate improvement. An analysis of ensemble predictions shows that the best ensembles are not necessarily those containing the best individual models. Conversely, it appears that some models that predict well individually do not necessarily combine well with other models in multi-model ensembles. The reasons behind these observations may relate to the effects of the weighting schemes, non-stationarity of the climate series and possible cross-correlations between models. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.

  • 312. Weichselgartner, Juergen
    et al.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Evolving Climate Services into Knowledge-Action Systems2019Ingår i: Weather, Climate, and Society, ISSN 1948-8327, E-ISSN 1948-8335, Vol. 11, nr 2, s. 385-399Artikel i tidskrift (Refereegranskat)
  • 313.
    Wetterhall, Fredrik
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Bardossy, Andras
    Chen, Deliang
    Halldin, Sven
    Xu, Chong-Yu
    Daily precipitation-downscaling techniques in three Chinese regions2006Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 42, nr 11, artikel-id W11423Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    [ 1] Four methods of statistical downscaling of daily precipitation were evaluated on three catchments located in southern, eastern, and central China. The evaluation focused on seasonal variation of statistical properties of precipitation and indices describing the precipitation regime, e. g., maximum length of dry spell and maximum 5-day precipitation, as well as interannual and intra-annual variations of precipitation. The predictors used in this study were mean sea level pressure, geopotential heights at 1000, 850, 700, and 500 hPa, and specific humidity as well as horizontal winds at 850, 700, and 500 hPa levels from the NCEP/NCAR reanalysis with 2.5 degrees x 2.5 degrees resolution for 1961 - 2000. The predictand was daily precipitation from 13 stations. Two analogue methods, one using principal components analysis (PCA) and the other Teweles-Wobus scores (TWS), a multiregression technique with a weather generator producing precipitation (SDSM) and a fuzzy-rule-based weather-pattern-classification method (MOFRBC), were used. Temporal and spatial properties of the predictors were carefully evaluated to derive the optimum setting for each method, and MOFRBC and SDSM were implemented in two modes, with and without humidity as predictor. The results showed that ( 1) precipitation was most successfully downscaled in the southern and eastern catchments located close to the coast, ( 2) winter properties were generally better downscaled, ( 3) MOFRBC and SDSM performed overall better than the analogue methods, ( 4) the modeled interannual variation in precipitation was improved when humidity was added to the predictor set, and ( 5), the annual precipitation cycle was well captured with all methods.

  • 314.
    Wetterhall, Fredrik
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Bardossy, Andras
    Chen, Deliang
    Halldin, Sven
    Xu, Chong-yu
    Statistical downscaling of daily precipitation over Sweden using GCM output2009Ingår i: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 96, nr 1-2, s. 95-103Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A classification of Swedish weather patterns (SWP) was developed by applying a multi-objective fuzzy-rule-based classification method (MOFRBC) to large-scale-circulation predictors in the context of statistical downscaling of daily precipitation at the station level. The predictor data was mean sea level pressure (MSLP) and geopotential heights at 850 (H850) and 700 hPa (H700) from the NCEP/NCAR reanalysis and from the HadAM3 GCM. The MOFRBC was used to evaluate effects of two future climate scenarios (A2 and B2) on precipitation patterns on two regions in south-central and northern Sweden. The precipitation series were generated with a stochastic, autoregressive model conditioned on SWP. H850 was found to be the optimum predictor for SWP, and SWP could be used instead of local classifications with little information lost. The results in the climate projection indicated an increase in maximum 5-day precipitation and precipitation amount on a wet day for the scenarios A2 and B2 for the period 2070-2100 compared to 1961-1990. The relative increase was largest in the northern region and could be attributed to an increase in the specific humidity rather than to changes in the circulation patterns.

  • 315.
    Wetterhall, Fredrik
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Graham, Phil
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Andreasson, Johan
    SMHI, Affärsverksamhet.
    Rosberg, Jörgen
    SMHI, Forskningsavdelningen, Hydrologi.
    Yang, Wei
    SMHI, Forskningsavdelningen, Hydrologi.
    Using ensemble climate projections to assess probabilistic hydrological change in the Nordic region2011Ingår i: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 11, nr 8, s. 2295-2306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Assessing hydrological effects of global climate change at local scales is important for evaluating future hazards to society. However, applying climate model projections to local impact models can be difficult as outcomes can vary considerably between different climate models, and including results from many models is demanding. This study combines multiple climate model outputs with hydrological impact modelling through the use of response surfaces. Response surfaces represent the sensitivity of the impact model to incremental changes in climate variables and show probabilies for reaching a priori determined thresholds. Response surfaces were calculated using the HBV hydrological model for three basins in Sweden. An ensemble of future climate projections was then superimposed onto each response surface, producing a probability estimate for exceeding the threshold being evaluated. Site specific impacts thresholds were used where applicable. Probabilistic trends for future change in hazards or potential can be shown and evaluated. It is particularly useful for visualising the range of probable outcomes from climate models and can easily be updated with new results as they are made available.

  • 316.
    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.

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

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

  • 318. White, Christopher J.
    et al.
    Carlsen, Henrik
    Robertson, Andrew W.
    Klein, Richard J. T.
    Lazo, Jeffrey K.
    Kumar, Arun
    Vitart, Frederic
    de Perez, Erin Coughlan
    Ray, Andrea J.
    Murray, Virginia
    Bharwani, Sukaina
    MacLeod, Dave
    James, Rachel
    Fleming, Lora
    Morse, Andrew P.
    Eggen, Bernd
    Graham, Richard
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Becker, Emily
    Pegion, Kathleen V.
    Holbrook, Neil J.
    McEvoy, Darryn
    Depledge, Michael
    Perkins-Kirkpatrick, Sarah
    Brown, Timothy J.
    Street, Roger
    Jones, Lindsey
    Remenyi, Tomas A.
    Hodgson-Johnston, Indi
    Buontempo, Carlo
    Lamb, Rob
    Meinke, Holger
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Zebiak, Stephen E.
    Potential applications of subseasonal-to-seasonal (S2S) predictions2017Ingår i: Meteorological Applications, ISSN 1350-4827, E-ISSN 1469-8080, Vol. 24, nr 3, s. 315-325Artikel i tidskrift (Refereegranskat)
  • 319. Widmann, Martin
    et al.
    Bedia, Joaquin
    Gutierrez, Jose M.
    Bosshard, Thomas
    SMHI, Forskningsavdelningen, Hydrologi.
    Hertig, Elke
    Maraun, Douglas
    Casado, Maria J.
    Ramos, Petra
    Cardoso, Rita M.
    Soares, Pedro M. M.
    Ribalaygua, Jamie
    Page, Christian
    Fischer, Andreas M.
    Herrera, Sixto
    Huth, Radan
    Validation of spatial variability in downscaling results from the VALUE perfect predictor experiment2019Ingår i: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 39, nr 9, s. 3819-3845Artikel i tidskrift (Refereegranskat)
  • 320. Wilk, J.
    et al.
    Andersson, Lotta
    SMHI, Samhälle och säkerhet. SMHI, Forskningsavdelningen, Hydrologi.
    Graham, Phil
    SMHI, Affärsverksamhet.
    Wikner, J. J.
    Mokwatlo, S.
    Petja, B.
    From forecasts to action - What is needed to make seasonal forecasts useful for South African smallholder farmers?2017Ingår i: International Journal of Disaster Risk Reduction, E-ISSN 2212-4209, Vol. 25, s. 202-211Artikel i tidskrift (Refereegranskat)
  • 321.
    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.

  • 322. Wilk, Julie
    et al.
    Hjerpe, Mattias
    Yang, Wei
    SMHI, Forskningsavdelningen, Hydrologi.
    Fan, Hua
    Farm-scale adaptation under extreme climate and rapid economic transition2015Ingår i: Environment, Development and Sustainability, ISSN 1387-585X, E-ISSN 1573-2975, Vol. 17, nr 3, s. 393-407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper aims to analyse what shapes farmers' vulnerability and adaptation strategies in the context of rapid change. Xinjiang is semi-arid, with extremes of temperature, growing seasons and winds. Favourable socioeconomic conditions have boosted the wellbeing of farmers in the past decades. Interviews with forty-seven farmers led to the categorization of five groups according to the predominant type of farming activity: animal farmers, government farmers (leasing land from the Xinjiang Production and Construction Group), crop farmers, agri-tourism operators and entrepreneurs. High government support has aided farmers to deal with climate challenges, through advanced technology, subsidies and loans. Farmers, however, greatly contribute to their own high adaptive capacity through inventiveness, flexibility and a high knowledge base. Although the future climate will entail hotter temperatures, farmers can be seen as generally well equipped to deal with these challenges because of the high adaptive capacity they currently have and utilize. Those that are most vulnerable are those that have difficulty to access credit e.g. animal farmers and those that do not want to change their agricultural systems e.g. from pastoral lifestyles to include tourism-based operations.

  • 323.
    Wilk, Julie
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Jonsson, Anna
    SMHI, Samhälle och säkerhet.
    Rydhagen, Birgitta
    Rani, Ashu
    Kumar, Arun
    The perspectives of the urban poor in climate vulnerability assessments - The case of Kota, India2018Ingår i: Urban Climate, ISSN 2212-0955, E-ISSN 2212-0955, Vol. 24, s. 633-642Artikel i tidskrift (Refereegranskat)
  • 324. Willems, P.
    et al.
    Arnbjerg-Nielsen, K.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Nguyen, V. T. V.
    Climate change impact assessment on urban rainfall extremes and urban drainage: Methods and shortcomings2012Ingår i: Atmospheric research, ISSN 0169-8095, E-ISSN 1873-2895, Vol. 103, s. 106-118Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 325. Winterdahl, Mattias
    et al.
    Laudon, Hjalmar
    Lyon, Steve W.
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Bishop, Kevin
    Sensitivity of stream dissolved organic carbon to temperature and discharge: Implications of future climates2016Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, nr 1, s. 126-144Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dissolved organic carbon (DOC) is a significant constituent in aquatic ecosystems with concentrations in streams influenced by both temperature and water flow pathway dynamics associated with changes in discharge (streamflow). We investigated the sensitivity of DOC concentrations in 12 high-latitude headwater streams to changes in temperature and discharge using a mathematical model. The implications of differences in sensitivities were explored by using downscaled projections of air temperature and discharge to simulate possible trajectories of DOC concentrations in a changing climate. We found two distinct responses: (i) catchments where stream DOC sensitivity was high to temperature but low to discharge and (ii) catchments where stream DOC sensitivity was low to temperature but high to discharge. Streams with strong seasonal DOC dynamics were more sensitive to temperature changes than nonseasonal systems. In addition, stream DOC sensitivity to discharge was strongly correlated with vertical soil water DOC differences in the near-stream zone. Simulations of possible future changes in DOC concentrations indicated median increases of about 4-24% compared to current levels when using projections of air temperature and discharge but even larger increases were observed for base flow concentrations (13-42%). Streams with high-temperature sensitivity showed the largest increases in DOC concentrations. Our results suggest that future climatic changes could bring significant increases in surface water DOC concentrations in boreal and hemiboreal areas but that the response ultimately is dependent on vertical soil solution DOC differences and soil organic carbon distribution.

  • 326. Winterdahl, Mattias
    et al.
    Temnerud, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Futter, Martyn N.
    Lofgren, Stefan
    Moldan, Filip
    Bishop, Kevin
    Riparian Zone Influence on Stream Water Dissolved Organic Carbon Concentrations at the Swedish Integrated Monitoring Sites2011Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, nr 8, s. 920-930Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Short-term variability in stream water dissolved organic carbon (DOC) concentrations is controlled by hydrology, climate and atmospheric deposition. Using the Riparian flow-concentration Integration Model (RIM), we evaluated factors controlling stream water DOC in the Swedish Integrated Monitoring (IM) catchments by separating out hydrological effects on stream DOC dynamics. Model residuals were correlated with climate and deposition-related drivers. DOC was most strongly correlated to water flow in the northern catchment (Gammtratten). The southern Aneboda and Kindla catchments had pronounced seasonal DOC signals, which correlated weakly to flow. DOC concentrations at GAyenrdsjon increased, potentially in response to declining acid deposition. Soil temperature correlated strongly with model residuals at all sites. Incorporating soil temperature in RIM improved model performance substantially (20-62% lower median absolute error). According to the simulations, the RIM conceptualization of riparian processes explains between 36% (Kindla) and 61% (Aneboda) of the DOC dynamics at the IM sites.

  • 327.
    Wittgren, Hans Bertil
    et al.
    SMHI, Forskningsavdelningen.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Source apportionment of riverine nitrogen transport based on catchment modelling1996Ingår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 33, nr 4-5, s. 109-115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Source apportionment of river substance transport, i.e. estimation of how much each source in each subbasin contributes to the river-mouth transport is a vital step in achieving the most efficient management practices to reduce pollutant loads to the sea. In this study, the spatially lumped (at sub-catchment level), semiempirical PULSE hydrological model, with a nitrogen routine coupled to if was used to perform source apportionment of nitrogen transport in the Soderkopingsan river basin (882 km(2)) in south-eastern Sweden, for the period 1991-93. The river basin was divided into 28 subbasins and the following sources were considered: land leakage from the categories forest arable and ley/pasture; point sources, and; atmospheric deposition on lake surfaces. The calibrated model yielded an explained variance of 60%, based on comparison of measured and modelled river nitrogen (Total N) concentrations. Eight subbasins, with net contributions to the river-mouth transport exceeding 3 kg ha(-1) yr(-1), were identified as the most promising candidates for cost efficient nitrogen management. The other 20 subbasins all had net contributions below 3 kg ha(-1) yr(-1). Arable land contributed 63% of the nitrogen transport at the river mouth and would thus be in focus for management measures. However, point sources (18% contribution to net transport) should also be considered due to their relatively high accessibility for removal measures (high concentrations). E.g., the most downstream subbasin, with the largest wastewater treatment plant in the whole river basin, had a net contribution of 16 kg ha(-1) yr(-1). This method for source apportionment may provide authorities with quantitative information about where in a river basin, and at which sources, they should focus their attention. However, once this is done, an analysis with higher resolution has to be performed in each of the interesting subbasins, before decisions on actual management measures can be taken. Copyright (C) 1996 IAWQ.

  • 328. Worman, A.
    et al.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Riml, Joakim
    SMHI, Forskningsavdelningen, Hydrologi.
    The power of runoff2017Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 548, s. 784-793Artikel i tidskrift (Refereegranskat)
  • 329. Worman, Anders
    et al.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Akesson, Anna
    Riml, Joakim
    SMHI, Forskningsavdelningen, Hydrologi.
    Drifting runoff periodicity during the 20th century due to changing surface water volume2010Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, nr 26, s. 3772-3784Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fourier and wavelet analyses were used to reveal the dominant trends and coherence of a more than one-century-long time series of precipitation and discharge in several watersheds in Sweden, two of which were subjected to hydropower and intensive agriculture. During the 20th century, there was a gradual, significant drift of the dominant discharge periodicity in agricultural watersheds. This study shows that the steepness of the Fourier spectrum of runoff from the May to October period each year increased gradually during the century, which suggests a more predictable intra-annual runoff pattern (more apart from white-noise). In the agricultural watershed, the coherence spectrum of precipitation and runoff is generally high with a consistent white-noise relationship for precipitation during the 20th century, indicating that precipitation is not controlling the drift of the discharge spectrum. In the hydropower regulated watershed, there was a sudden decrease of the discharge spectrum slope when regulation commenced in the 1920s. This study develops a new theory in which the runoff spectrum is related to the hydraulic and hydro-morphological characteristics of the watershed. Using this theory, we explain the changes in runoff spectra in the two watersheds by the anthropogenic change in surface water volume and, hence, changes in kinematic wave celerity and water transit times. The reduced water volume in the agricultural watershed would also contribute to decreasing evaporation, which could explain a slightly increasing mean discharge during the 20th century despite the fact that precipitation was statistically constant in the area. Copyright (C) 2010 John Wiley & Sons, Ltd.

  • 330.
    Yang, Wei
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Andreasson, Johan
    SMHI, Affärsverksamhet.
    Graham, Phil
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Rosberg, Jörgen
    SMHI, Forskningsavdelningen, Hydrologi.
    Wetterhall, Fredrik
    SMHI, Forskningsavdelningen, Hydrologi.
    Distribution-based scaling to improve usability of regional climate model projections for hydrological climate change impacts studies2010Ingår i: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 41, nr 3-4, s. 211-229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As climate change could have considerable influence on hydrology and corresponding water management, appropriate climate change inputs should be used for assessing future impacts. Although the performance of regional climate models (RCMs) has improved over time, systematic model biases still constrain the direct use of RCM output for hydrological impact studies. To address this, a distribution-based scaling (DBS) approach was developed that adjusts precipitation and temperature from RCMs to better reflect observations. Statistical properties, such as daily mean, standard deviation, distribution and frequency of precipitation days, were much improved for control periods compared to direct RCM output. DBS-adjusted precipitation and temperature from two IPCC Special Report on Emissions Scenarios (SRESA1B) transient climate projections were used as inputs to the HBV hydrological model for several river basins in Sweden for the period 1961-2100. Hydrological results using DBS were compared to results with the widely-used delta change (DC) approach for impact studies. The general signal of a warmer and wetter climate was obtained using both approaches, but use of DBS identified differences between the two projections that were not seen with DC. The DBS approach is thought to better preserve the future variability produced by the RCM, improving usability for climate change impact studies.

  • 331.
    Yang, Wei
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Bardossy, Andras
    Caspary, Hans-Joachim
    Downscaling daily precipitation time series using a combined circulation- and regression-based approach2010Ingår i: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 102, nr 3-4, s. 439-454Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this paper is to introduce a new conditional statistical model for generating daily precipitation time series. The generated daily precipitation can thus be used for climate change impact studies, e.g., crop production, rainfall-runoff, and other water-related processes. It is a stochastic model that links local rainfall events to a continuous atmospheric predictor, moisture flux, in addition to classified atmospheric circulation patterns. The coupled moisture flux is proved to be capable of capturing continuous property of climate system and providing extra information to determine rainfall probability and rainfall amount. The application was made to simultaneously downscale daily precipitation at multiple sites within the Rhine River basin. The results show that the model can well reproduce statistical properties of daily precipitation time series. Especially for extreme rainfall events, the model is thought to better reflect rainfall variability compared to the pure CP-based downscaling approach.

  • 332.
    Yang, Wei
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Gardelin, Marie
    SMHI, Affärsverksamhet.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Bosshard, Thomas
    SMHI, Forskningsavdelningen, Hydrologi.
    Multi-variable bias correction: application of forest fire risk in present and future climate in Sweden2015Ingår i: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 15, nr 9, s. 2037-2057Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As the risk of a forest fire is largely influenced by weather, evaluating its tendency under a changing climate becomes important for management and decision making. Currently, biases in climate models make it difficult to realistically estimate the future climate and consequent impact on fire risk. A distribution-based scaling (DBS) approach was developed as a post-processing tool that intends to correct systematic biases in climate modelling outputs. In this study, we used two projections, one driven by historical reanalysis (ERA40) and one from a global climate model (ECHAM5) for future projection, both having been dynamically down-scaled by a regional climate model (RCA3). The effects of the post-processing tool on relative humidity and wind speed were studied in addition to the primary variables precipitation and temperature. Finally, the Canadian Fire Weather Index system was used to evaluate the influence of changing meteorological conditions on the moisture content in fuel layers and the fire-spread risk. The forest fire risk results using DBS are proven to better reflect risk using observations than that using raw climate outputs. For future periods, southern Sweden is likely to have a higher fire risk than today, whereas northern Sweden will have a lower risk of forest fire.

  • 333. Yin, Yunxing
    et al.
    Jiang, Sanyuan
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Yang, Xiaoying
    Liu, Qun
    Yuan, Jin
    Yao, Mingxing
    He, Yi
    Luo, Xingzhang
    Zheng, Zheng
    Assessment of the Spatial and Temporal Variations of Water Quality for Agricultural Lands with Crop Rotation in China by Using a HYPE Model2016Ingår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 13, nr 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many water quality models have been successfully used worldwide to predict nutrient losses from anthropogenically impacted catchments, but hydrological and nutrient simulations with limited data are difficult considering the transfer of model parameters and complication of model calibration and validation. This study aims: (i) to assess the performance capabilities of a new and relatively more advantageous model, namely, Hydrological Predictions for the Environment (HYPE), that simulates stream flow and nutrient load in agricultural areas by using a multi-site and multi-objective parameter calibration method and (ii) to investigate the temporal and spatial variations of total nitrogen (TN) and total phosphorous (TP) concentrations and loads with crop rotation by using the model for the first time. A parameter estimation tool (PEST) was used to calibrate parameters. Results show that the parameters related to the effective soil porosity were highly sensitive to hydrological modeling. N balance was largely controlled by soil denitrification processes. P balance was influenced by the sedimentation rate and production/decay of P in rivers and lakes. The model reproduced the temporal and spatial variations of discharge and TN/TP relatively well in both calibration (2006-2008) and validation (2009-2010) periods. Among the obtained data, the lowest Nash-Suttclife efficiency of discharge, daily TN load, and daily TP load were 0.74, 0.51, and 0.54, respectively. The seasonal variations of daily TN concentrations in the entire simulation period were insufficient, indicated that crop rotation changed the timing and amount of N output. Monthly TN and TP simulation yields revealed that nutrient outputs were abundant in summer in terms of the corresponding discharge. The area-weighted TN and TP load annual yields in five years showed that nutrient loads were extremely high along Hong and Ru rivers, especially in agricultural lands.

  • 334. Zhang, Linus
    et al.
    Gustafsson, David
    SMHI, Forskningsavdelningen, Hydrologi.
    Editorial: 'The Nordic Hydrology Model' - Linking science and practice2016Ingår i: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 47, nr 4, s. 671-671Artikel i tidskrift (Refereegranskat)
  • 335. Zhang, X N
    et al.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    A comparative study of a Swedish and a Chinese hydrological model1996Ingår i: WATER RESOURCES BULLETIN, ISSN 0043-1370, Vol. 32, nr 5, s. 985-994Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There are a large number of conceptual hydrological models available today. It is not easy to immediately identify the similarities and differences between the different models. The Swedish HBV model and the Chinese Xinanjiang model are two examples of conceptual, semi-distributed, rainfall-runoff models. The Xinanjiang model was designed for use in humid and semi-humid regions, with no routine for the snowmelt runoff, whereas the snow routine is an important part of the HBV model in many applications. The model structures of the two models may be described in four routines, compared in this paper. The integral structures of them are similar, but there are some differences, especially in the runoff production routine. The physical significance and physical definitions of some model parameters were analyzed. Both models were tested in two basins. Both models gave similar results, and both models performed well in the application. The similarity of the results obtained by different model structures leads to the following two conclusions. First, more effort should probably be spent on the improvement of input data quality and coverage than on the development of more detailed model structures only. Second, inference about basin behavior and characteristics from the values of calibrated model parameters must be made with great caution.

4567 301 - 335 av 335
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