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  • 1.
    Andersson, Jafet
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Traore, Farid
    Gustafsson, David
    SMHI, Forskningsavdelningen, Hydrologi.
    Ali, Abdou
    Process refinements improve a hydrological model concept applied to the Niger River basin2017Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 31, nr 25, s. 4540-4554Artikel i tidskrift (Refereegranskat)
  • 2.
    Bergström, Sten
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Samhälle och säkerhet.
    Interpretation of runoff processes in hydrological modelling experience from the HBV approach2015Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, nr 16, s. 3535-3545Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The process of development and application of the Hydrologiska Byrans Vattenbalansavdelning hydrological model over a time period of more than 40years is reviewed and discussed. Emphasis is on the early modelling strategy and physical considerations based on contemporary research on runoff formation processes in the drainage basin. This includes areal considerations on the catchment scale, soil moisture and evapotranspiration and storages and discharge as represented by the response function of the model. The introduction of the concept of dynamic recharge and discharge areas is also addressed as well as the modelling of snow accumulation and melt. Some operational international experiences are also addressed. Copyright (c) 2015 John Wiley & Sons, Ltd.

  • 3.
    Bergström, Sten
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Pettersson, Anna
    SMHI, Forskningsavdelningen, Hydrologi.
    Multi-variable parameter estimation to increase confidence in hydrological modelling2002Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 16, nr 2, s. 413-421Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The expanding use and increased complexity of hydrological runoff models has given rise to a concern about overparameterization and risks for compensating errors. One proposed way out is the calibration and validation against additional observations, such as snow, soil moisture, groundwater or water quality. A general problem, however, when calibrating the model against more than one variable is the strategy for parameter estimation. The most straightforward method is to calibrate the model components sequentially. Recent results show that in this way the model may be locked up in a parameter setting, which is good enough for one variable but excludes proper simulation of other variables. This is particularly the case for water quality modelling, where a small compromise in terms of runoff simulation may lead to dramatically better simulations of water quality. This calls for an integrated model calibration procedure with a criterion that integrates more aspects on model performance than just river runoff. The use of multi-variable parameter estimation and internal control of the HBV hydrological model is discussed and highlighted by two case studies. The first example is from a forested basin in northern Sweden and the second one is from an agricultural basin in the south of the country. A new calibration strategy, which is integrated rather than sequential, is proposed and tested. It is concluded that comparison of model results with more measurements than only runoff can lead to increased confidence in the physical relevance of the model, and that the new calibration strategy can be useful for further model development. Copyright (C) 2002 John Wiley Sons, Ltd.

  • 4. Dahlke, Helen E.
    et al.
    Behrens, Thorsten
    Seibert, Jan
    Andersson, Lotta
    SMHI, Samhälle och säkerhet.
    Test of statistical means for the extrapolation of soil depth point information using overlays of spatial environmental data and bootstrapping techniques2009Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 23, nr 21, s. 3017-3029Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrological modelling depends highly on the accuracy and uncertainty of model input parameters such as soil properties. Since most of these data are field Surveyed, geostatistical techniques Such as kriging, classification and regression trees or more sophisticated soil-landscape models need to be applied to interpolate point information to the area. Most of the existing interpolation techniques require a random or regular distribution of points Within the study area but are not adequate to satisfactorily interpolate soil catena or transect data. The soil landscape model presented in this study is predicting soil information from transect or catena point data using a statistical mean (arithmetic, geometric and harmonic mean) to calculate the soil information based on class means of merged spatial explanatory variables. A data set of 226 soil depth measurements covering a range of 0-6.5 m was used to test the model. The point data were sampled along four transects in the Stubbetorp catchment, SE-Sweden. We overlaid a geomorphology map (8 classes) with digital elevation model-derived topographic index maps (2-9 classes) to estimate the range of error the model produces with changing sample size and input maps. The accuracy of the soil depth predictions was estimated with the root mean square error (RMSE) based oil a testing and training data set. RMSE ranged generally between 0.73 and 0.83 m +/- 0.013 m depending on the amount of classes the merged layers had, but were smallest for a map combination with a low number of classes predicted with the harmonic mean (RMSE = 0.46 m). The results show that the prediction accuracy of this method depends oil the number of point values in the sample, the value range of the measured attribute and the initial correlations between point values and explanatory variables, but suggests that the model approach is in general scale invariant. Copyright (C) 2009 John Wiley & Sons, Ltd.

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

    The intersection of the developing topic of rating curve and discharge series uncertainty with the topic of hydrological change detection (e.g., in response to land cover or climatic change) has not yet been well studied. The work herein explores this intersection, with consideration of a long-term discharge response (1964-2007) for a similar to 650-km(2) headwater basin of the Mara River in west Kenya, starting with stream rating and daily gauge height data. A rating model was calibrated using Bayesian methods to quantify uncertainty intervals in model parameters and predictions. There was an unknown balance of random and systemic error in rating data scatter (a scenario not likely unique to this basin), which led to an unknown balance of noise and information in the calibrated statistical error model. This had implications on testing for hydrological change. Overall, indications were that shifts in basin's discharge response were rather subtle over the 44-year period. A null hypothesis for change using flow duration curves (FDCs) from four different 8-year data intervals could be either accepted or rejected over much of the net flow domain depending on different applications of the statistical error model (each with precedence in the literature). The only unambiguous indication of change in FDC comparisons appeared to be a reduction in lowest baseflow in recent years (flows with >98% exceedance probability). We defined a subjective uncertainty interval based on an intermediate balance of random and systematic error in the rating model that suggested a possibility of more prevalent impacts. These results have relevance to management in the Mara basin and to future studies that might establish linkages to historic land use and climatic factors. The concern about uncertain uncertainty intervals (uncertainty(2)) extends beyond the Mara and is relevant to testing change where non-random rating errors may be important and subtle responses are investigated. Copyright (c) 2013 John Wiley & Sons, Ltd.

  • 6.
    Lindström, Göran
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Bishop, K
    Lofvenius, M O
    Soil frost and runoff at Svartberget, northern Sweden - measurements and model analysis2002Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 16, nr 17, s. 3379-3392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of soil frost on runoff was investigated using a comprehensive data set collected at the Svartberget Experimental Forest, near Vindeln, Vasterbotten in northern Sweden. Measurements of snow depth, soil temperature, frost depth and other climate parameters have been made at three sites since 1981, as part of a long-term climate monitoring programme. Simulation residuals from the HBV rainfall-runoff model, in which no effect of soil frost is assumed, were compared with 16 years of measured soil frost conditions. A simple model for simulation of soil frost depth was developed and incorporated into the HBV model. The model parameters were calibrated to observations of snow depth, soil frost depth, groundwater levels and runoff, by use of a simple weighted optimization criterion. No clear effect of soil frost could be seen on the timing and magnitude of runoff in this analysis, or when analysing data on the conservative oxygen isotope O-18. The soil at the forested site froze in only slightly more than half the years, despite the high latitude and low winter temperatures. Furthermore, the soil had often thawed before the start of the spring flood. Almost all spring floods, therefore, occurred when the soil was unfrozen. Snow depth and soil frost depths were inversely related, with the deepest soil frost during winters with little snow. Soil frost therefore is unlikely to aggravate the very high floods in forested basins of this type, except perhaps under exceptional circumstances such as large rain events on frozen ground. Copyright (C) 2002 John Wiley Sons, Ltd.

  • 7.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Burlando, P
    Reproduction of temporal scaling by a rectangular pulses rainfall model2002Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 16, nr 3, s. 611-630Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The presence of scaling statistical properties in temporal rainfall has been well established in many empirical investigations during the latest decade. These properties have more and more come to be regarded as a fundamental feature of the rainfall process. How to best use the scaling properties for applied modelling remains to be assessed, however, particularly in the case of continuous rainfall time-series. One therefore is forced to use conventional time-series modelling, e.g. based on point process theory, which does not explicitly take scaling into account. In light of this, there is a need to investigate the degree to which point-process models are able to unintentionally reproduce the empirical scaling properties. In the present study, four 25-year series of 20-min rainfall intensities observed in Arno River basin, Italy, were investigated. A Neyman-Scott rectangular pulses (NSRP) model was fitted to these series, so enabling the generation of synthetic time-series suitable for investigation. A multifractal scaling behaviour was found to characterize the raw data within a range of time-scales between approximately 20 min and 1 week. The main features of this behaviour were surprisingly well reproduced in the simulated data, although some differences were observed, particularly at small scales below the typical duration of a rain cell. This suggests the possibility of a combined use of the NSRP model and a scaling approach, in order to extend the NSRP range of applicability for simulation purposes, Copyright (C) 2002 John Wiley Sons, Ltd.

  • 8.
    Pers, Charlotta
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Temnerud, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Modelling water, nutrients, and organic carbon in forested catchments: a HYPE application2016Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, nr 18, s. 3252-3273Artikel i tidskrift (Refereegranskat)
  • 9.
    Temnerud, Johan
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Foelster, J.
    Buffam, I.
    Laudon, H.
    Erlandsson, M.
    Bishop, K.
    Can the distribution of headwater stream chemistry be predicted from downstream observations?2010Ingår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, nr 16, s. 2269-2276Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Small streams with catchment areas <2 km(2) make up the majority of all stream length and are of great ecological importance. Surveys of first and second order streams reveal great spatial and temporal variability in the water chemistry of these headwaters, but their assessment presents a serious challenge since systematic, representative data are usually only collected in larger streams and rivers. Using low flow synoptic survey data from seven mesoscale Swedish catchments, this study tests the hypothesis that downstream monitoring data can be used to predict key features of the distribution of chemistry in headwater streams [median and interquartile range (IQR)]. Three ecologically relevant analytes were tested: pH, acid neutralizing capacity (ANC) and total organic carbon (TOC). For all seven catchments, the outlets (36-127 km(2)) were considerably less acid with lower TOC than the median of the headwaters (<2 km(2), N = 19-45). Among catchments, headwater median and IQR were positively correlated with the value at the outlet, for all three analytes. A univariate general linear model (GLM) was used to predict the headwater chemistry distribution for each catchment from its outlet chemistry, using the relationship established with the other six catchments. Headwater median pH and IQR of ANC were well predicted by a single downstream sample [median adj. R(2) similar to 0.7, normalized root mean squared error (NRMSE) <0.7]. Other response variables were not as well predicted, with median adj. R(2) ranging from 0.08 to 0.48, and NRMSE up to 1.1. A minority of models were significant at alpha = 0.05, in part due to the limited availability of catchments with such extensive survey data. However, the clear trends observed suggest that with additional model development, downstream chemistry could ultimately provide a valuable tool for characterizing the range of chemistry in the contributing headwaters. Copyright (C) 2010 John Wiley & Sons, Ltd.

  • 10. 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)
  • 11. 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.

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