Mansanarez Valentin

Valentin Mansanarez


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Arbetar vid Institutionen för naturgeografi
Besöksadress Svante Arrhenius väg 8
Postadress Inst för naturgeografi 106 91 Stockholm


I urval från Stockholms universitets publikationsdatabas
  • Norris Lam (et al.).

    Hydraulic models can be useful tools for developing reliable rating curves, however, uncertainties in the input measurements can have implications for the model results. In this study, we investigate the impact of uncertain input field measurements (i.e. stream channel topography, water surface slope, vegetation density, stage, and discharge) on rating curves generated with a physically-based hydraulic model. This is the first-time measurement uncertainties have been assessed with the hydraulic model and we demonstrate the method at a regularly monitored catchment in central Sweden. The results show that the modeling approach, calibrated with three gauging measurements, acquired at low to median flows, was able to generate rating curves with relatively constrained uncertainty for the highest observed stage (i.e. -12% and +46%) when all uncertainty sources were accounted for. These results suggest that this modeling approach could be applied to quickly develop reliable rating curves and simultaneously estimate the uncertainty in the rating curves. 

  • 2018. Julie E. Kiang (et al.). Water resources research 54 (10), 7149-7176

    Streamflow time series are commonly derived from stage-discharge rating curves, but the uncertainty of the rating curve and resulting streamflow series are poorly understood. While different methods to quantify uncertainty in the stage-discharge relationship exist, there is limited understanding of how uncertainty estimates differ between methods due to different assumptions and methodological choices. We compared uncertainty estimates and stage-discharge rating curves from seven methods at three river locations of varying hydraulic complexity. Comparison of the estimated uncertainties revealed a wide range of estimates, particularly for high and low flows. At the simplest site on the Is&e River (France), full width 95% uncertainties for the different methods ranged from 3 to 17% for median flows. In contrast, uncertainties were much higher and ranged from 41 to 200% for high flows in an extrapolated section of the rating curve at the Mahurangi River (New Zealand) and 28 to 101% for low flows at the Taf River (United Kingdom), where the hydraulic control is unstable at low flows. Differences between methods result from differences in the sources of uncertainty considered, differences in the handling of the time-varying nature of rating curves, differences in the extent of hydraulic knowledge assumed, and differences in assumptions when extrapolating rating curves above or below the observed gaugings. Ultimately, the selection of an uncertainty method requires a match between user requirements and the assumptions made by the uncertainty method. Given the significant differences in uncertainty estimates between methods, we suggest that a clear statement of uncertainty assumptions be presented alongside streamflow uncertainty estimates. Plain Language Summary Knowledge of the uncertainty in streamflow discharge measured at gauging stations is important for water management applications and scientific analysis. This paper shows that uncertainty estimates vary widely (typically up to a factor of 4) when comparing seven recently introduced estimation methods. A clear understanding of the assumptions underpinning different uncertainty estimation methods and the sources of uncertainty included in their calculations is needed when selecting a method and using and presenting its uncertainty estimates.

  • 2017. Valentin Mansanarez (et al.). La houille blanche (5), 22-28

    An original hydraulics-based Bayesian method is introduced for developing stage-fall-discharge (SFD) rating curves used at twin-gauge stations and estimating their uncertainties. A channel control with variable energy slope due to variable backwater is considered in combination with a backwater-unaffected control, usually another channel control. Succession between backwater-affected and backwater-unaffected controls is solved based on the continuity of the stage-discharge relation. The difference between the reference levels at the two stations is estimated as another uncertain parameter of the SFD model. Results at one typical twin-gauge station affected by the backwater of a run-of-the-river dam are presented. The accuracy and uncertainty of predicted discharges appear to be acceptable even when the uncertainty of the transition between backwater-affected and backwater-unaffected controls is high.

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Senast uppdaterad: 3 april 2019

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