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Towards high resolution calibration-free modelling
with seamless large-domain parameter estimates
Ruben Imhoff, Willem van...
8 november 2018
Contents
1. Background and motivation
2. Model parameter estimations – ‘Towards calibration-free modelling...
Background and motivation
Distributed hydrological models, a
pleasure or a burden?
Transition to distributed models
comes ...
Background and motivation
So what can we do?
• Pedo-transfer functions (PTFs) -
Parameter estimates
• Convenient regionali...
Model parameter estimations
Step 1: High resolution data
• ISRIC SoilGrids 250m – global
soil database [Hengl et al., 2017...
Model parameter estimations
An example of the pedo-transfer functions
8 november 2018
Background
Parameter
estimatesApplic...
Model parameter estimations
• Soil data available at various
depths  wflow_sbm set up
with four soil layers
• All sensiti...
Application in the Rhine basin - Results
Discharge simulations
8 november 2018
Background
Parameter
estimates
Application
...
Application in the Rhine basin - Results
Evapotranspiration estimates
8 november 2018
Background
Parameter
estimates
Appli...
Application in the Rhine basin - Results
Estimates at different resolutions
8 november 2018
Background
Parameter
estimates...
Lessons learned from an intercomparison study in the
United States
Intercomparison study with VIC model – collaboration wi...
Lessons learned from an intercomparison study in the
United States
General overview results
Reached KGE for discharge simu...
Lessons learned from an intercomparison study in the
United States
Improvements in soil
evaporation module
• Soil evaporat...
Lessons learned from an intercomparison study in the
United States
Importance of root water uptake reductions during dry p...
Wrap-up and Outlook
Code improvements and lessons learned
• Two-step soil evaporation procedure (available in latest versi...
Wrap-up and Outlook
Outlook
• Easy model setup
• Calibration an option to further tune model for operational
use  But not...
Questions?
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DSD-INT 2018 Distributed hydrologic modelling with wflow_sbm: towards high resolution calibration-free modelling with seamless large-domain parameter estimates - Imhoff

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Presentation by Ruben Imhoff (WUR) at the wflow User Day 2018, during Delft Software Days - Edition 2018. Friday 09 November 2018, Delft.

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DSD-INT 2018 Distributed hydrologic modelling with wflow_sbm: towards high resolution calibration-free modelling with seamless large-domain parameter estimates - Imhoff

  1. 1. Towards high resolution calibration-free modelling with seamless large-domain parameter estimates Ruben Imhoff, Willem van Verseveld, Bart van Osnabrugge, Albrecht Weerts Delft Software Days - November 9th, 2018 Distributed hydrological modelling with wflow_sbm
  2. 2. 8 november 2018 Contents 1. Background and motivation 2. Model parameter estimations – ‘Towards calibration-free modelling with seamless large domain parameter estimates’ 3. Application in the Rhine basin 4. Lessons learned from a intercomparison study in the United States a. Reduction of root water uptake b. Improvements in soil evaporation 5. Wrap-up and outlook
  3. 3. Background and motivation Distributed hydrological models, a pleasure or a burden? Transition to distributed models comes at a price: • Over-parameterized models • Patchy parameter maps • Limits climate and land use change studies • Calibration a burden for operational and policy use 8 november 2018 BackgroundParameter estimates Application Rhine ApplicationUSOutlook
  4. 4. Background and motivation So what can we do? • Pedo-transfer functions (PTFs) - Parameter estimates • Convenient regionalization techniques, e.g. Multiscale Parameter Regionalization (MPR) [Samaniego et al., 2010]. Applied for: • German model mHM [e.g. Samaniego et al., 2010; Kumar et al., 2013; Samaniego et al., 2017] • VIC [Mizukami et al., 2017] • Next step: same upscaling procedures, but no calibration involved 8 november 2018 BackgroundParameter estimates Application Rhine ApplicationUSOutlook Samaniego et al., 2010
  5. 5. Model parameter estimations Step 1: High resolution data • ISRIC SoilGrids 250m – global soil database [Hengl et al., 2017] • Forcing, e.g. genRE interpolation (1200 m, hourly) for Rhine basin [van Osnabrugge et al., 2017, 2018] Step 2: Parameter estimates at original data resolution Step 3: Convenient upscaling techniques to model resolution Step 4: Run your model 1.2 km resolution for the Rhine Now, 1 km resolution for the US 8 november 2018 Background Parameter estimatesApplication Rhine ApplicationUSOutlook Global parameters for PTFs(γ) Geophysical properties (μ) Tranfer-functions β = f(γ,μ) Upscaling (arithmetic mean, harmonic mean, geometric mean, etc.) Model simulation Calibration
  6. 6. Model parameter estimations An example of the pedo-transfer functions 8 november 2018 Background Parameter estimatesApplication Rhine ApplicationUSOutlook 1.2 km 2.4 km 3.6 km 4.8 km
  7. 7. Model parameter estimations • Soil data available at various depths  wflow_sbm set up with four soil layers • All sensitive parameters estimated (based on sensitivity analysis) • Strength of wflow_sbm • Model does not have to be calibrated! • Snow parameters still uniform and following HBV 8 november 2018 Background Parameter estimatesApplication Rhine ApplicationUSOutlook
  8. 8. Application in the Rhine basin - Results Discharge simulations 8 november 2018 Background Parameter estimates Application RhineApplicationUSOutlook
  9. 9. Application in the Rhine basin - Results Evapotranspiration estimates 8 november 2018 Background Parameter estimates Application RhineApplicationUSOutlook
  10. 10. Application in the Rhine basin - Results Estimates at different resolutions 8 november 2018 Background Parameter estimates Application RhineApplicationUSOutlook
  11. 11. Lessons learned from an intercomparison study in the United States Intercomparison study with VIC model – collaboration with National Center for Atmospheric Research 8 november 2018 Background Parameter estimates Application Rhine ApplicationUS Outlook 34 basins in the CONUS VICreg semi- distributed VICind semi- distributed Wflow_s bm distributed
  12. 12. Lessons learned from an intercomparison study in the United States General overview results Reached KGE for discharge simulations wflow_sbm with parameter estimates outperforms VICreg with calibrated transfer-functions. Individual basin calibration (VICind) still gives best performance 8 november 2018 Background Parameter estimates Application Rhine ApplicationUS Outlook
  13. 13. Lessons learned from an intercomparison study in the United States Improvements in soil evaporation module • Soil evaporation could only take place from unsaturated zone in upper layer • Problem for warm and humid catchments • New implementation – Two-step soil evaporation: 1. Unsaturated zone 2. Saturated zone • Importance of PET- estimations 8 november 2018 Background Parameter estimates Application Rhine ApplicationUS Outlook From To
  14. 14. Lessons learned from an intercomparison study in the United States Importance of root water uptake reductions during dry periods: The benefits of the Feddes transpiration reduction in wflow_sbm 8 november 2018 Background Parameter estimates Application Rhine ApplicationUS Outlook Feddes et al., 1978
  15. 15. Wrap-up and Outlook Code improvements and lessons learned • Two-step soil evaporation procedure (available in latest version) • Importance of transpiration reduction function (available in latest version) • Pay attention to forcing and in particular PET estimates Parameter estimates • Wflow_sbm can be run without further calibration • Promising results for the Rhine basin • Improvements to be made in sub-tropical and semi-arid regions (US case) • For operational use: possibly calibrate one or two parameters only (e.g. M and Ksat) 8 november 2018 Background Parameter estimates Application Rhine ApplicationUS Outlook
  16. 16. Wrap-up and Outlook Outlook • Easy model setup • Calibration an option to further tune model for operational use  But not always necessary! • Paper in preparation [Imhoff et al., WRR, 2018] • Global parameter maps on 1 km will come available soon >  See presentation by Albrecht Weerts on the CRUCIAL product for wflow_sbm global 8 november 2018 Background Parameter estimates Application Rhine ApplicationUS Outlook
  17. 17. Questions?

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