Ändra sökning
Avgränsa sökresultatet
1 - 4 av 4
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1. Hejzlar, J.
    et al.
    Anthony, S.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Behrendt, H.
    Bouraoui, F.
    Grizzetti, B.
    Groenendijk, P.
    Jeuken, M. H. J. L.
    Johnsson, H.
    Lo Porto, A.
    Kronvang, B.
    Panagopoulos, Y.
    Siderius, C.
    Silgram, M.
    Venohr, M.
    Zaloudik, J.
    Nitrogen and phosphorus retention in surface waters: an inter-comparison of predictions by catchment models of different complexity2009Ingår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 11, nr 3, s. 584-593Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nitrogen and phosphorus retention estimates in streams and standing water bodies were compared for four European catchments by a series of catchment-scale modelling tools of different complexity, ranging from a simple, equilibrium input-output type to dynamic, physical-based models: source apportionment, MONERIS, EveNFlow, TRK, SWAT, and NL-CAT. The four catchments represent diverse climate, hydrology, and nutrient loads from diffuse and point sources in Norway, the UK, Italy, and the Czech Republic. The models' retention values varied largely, with tendencies towards higher scatters for phosphorus than for nitrogen, and for catchments with lakes (Vansjo-Hobol, Z. elivka) compared to mostly or entirely lakeless catchments (Ouse or Enza, respectively). A comparison of retention values with the size of nutrient sources showed that the modelled nutrient export from diffuse sources was directly proportional to retention estimates, hence implying that the uncertainty in quantification of diffuse catchment sources of nutrients was also related to the uncertainty in nutrient retention determination. This study demonstrates that realistic modelling of nutrient export from large catchments is very difficult without a certain level of measured data. In particular, even complex process oriented models require information on the retention capabilities of water bodies within the receiving surface water system and on the nutrient export from micro-catchments representing the major types of diffuse sources to surface waters.

  • 2. 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, Forskningsavdelningen, Hydrologi.
    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 land2009Ingår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 11, nr 3, s. 540-553Artikel i tidskrift (Refereegranskat)
    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.

  • 3. Silgram, M.
    et al.
    Anthony, S. G.
    Collins, A. L.
    Stromqvist, J.
    Bouraoui, F.
    Schoumans, O.
    Lo Porto, A.
    Groenendijk, P.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Mimikou, M.
    Johnsson, H.
    Evaluation of diffuse pollution model applications in EUROHARP catchments with limited data2009Ingår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 11, nr 3, s. 554-571Artikel i tidskrift (Refereegranskat)
    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.

  • 4. Silgram, M.
    et al.
    Schoumans, O. F.
    Walvoort, D. J. J.
    Anthony, S. G.
    Groenendijk, P.
    Stromqvist, J.
    Bouraoui, F.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Kapetanaki, M.
    Lo Porto, A.
    Martensson, K.
    Subannual models for catchment management: evaluating model performance on three European catchments2009Ingår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 11, nr 3, s. 526-539Artikel i tidskrift (Refereegranskat)
    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.

1 - 4 av 4
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.7
|