Assessing the impact of model spin-up on surface water-groundwater interactions using an integrated hydrologic model

Handle URI:
http://hdl.handle.net/10754/552178
Title:
Assessing the impact of model spin-up on surface water-groundwater interactions using an integrated hydrologic model
Authors:
Ajami, Hoori; McCabe, Matthew ( 0000-0002-1279-5272 ) ; Evans, Jason P.; Stisen, Simon
Abstract:
Integrated land surface-groundwater models are valuable tools in simulating the terrestrial hydrologic cycle as a continuous system and exploring the extent of land surface-subsurface interactions from catchment to regional scales. However, the fidelity of model simulations is impacted not only by the vegetation and subsurface parameterizations, but also by the antecedent condition of model state variables, such as the initial soil moisture, depth to groundwater, and ground temperature. In land surface modeling, a given model is often run repeatedly over a single year of forcing data until it reaches an equilibrium state: the point at which there is minimal artificial drift in the model state or prognostic variables (most often the soil moisture). For more complex coupled and integrated systems, where there is an increased computational cost of simulation and the number of variables sensitive to initialization is greater than in traditional uncoupled land surface modeling schemes, the challenge is to minimize the impact of initialization while using the smallest spin-up time possible. In this study, multicriteria analysis was performed to assess the spin-up behavior of the ParFlow.CLM integrated groundwater-surface water-land surface model over a 208 km2 subcatchment of the Ringkobing Fjord catchment in Denmark. Various measures of spin-up performance were computed for model state variables such as the soil moisture and groundwater storage, as well as for diagnostic variables such as the latent and sensible heat fluxes. The impacts of initial conditions on surface water-groundwater interactions were then explored. Our analysis illustrates that the determination of an equilibrium state depends strongly on the variable and performance measure used. Choosing an improper initialization of the model can generate simulations that lead to a misinterpretation of land surface-subsurface feedback processes and result in large biases in simulated discharge. Estimated spin-up time from a series of spin-up functions revealed that 20 (or 21) years of simulation were sufficient for the catchment to equilibrate according to at least one criterion at the 0.1% (0.01%) threshold level. Amongst a range of convergence metrics examined, percentage changes in monthly values of groundwater and unsaturated zone storages produced a slow system convergence to equilibrium, whereas criteria based on ground temperature allowed a more rapid spin-up. Slow convergence of unsaturated and saturated zone storages is a result of the dynamic adjustment of the water table in response to a physically arbitrary or inconsistent initialization of a spatially uniform water table. Achieving equilibrium in subsurface storage ensured equilibrium across a spectrum of other variables, hence providing a good measure of system-wide equilibrium. Overall, results highlight the importance of correctly identifying the key variable affecting model equilibrium and also the need to use a multicriteria approach to achieve a rapid and stable model spin-up.
KAUST Department:
Water Desalination and Reuse Research Center (WDRC)
Citation:
Assessing the impact of model spin-up on surface water-groundwater interactions using an integrated hydrologic model 2014, 50 (3):2636 Water Resources Research
Journal:
Water Resources Research
Issue Date:
Mar-2014
DOI:
10.1002/2013WR014258
Type:
Article
ISSN:
00431397
Additional Links:
http://doi.wiley.com/10.1002/2013WR014258
Appears in Collections:
Articles; Water Desalination and Reuse Research Center (WDRC)

Full metadata record

DC FieldValue Language
dc.contributor.authorAjami, Hoorien
dc.contributor.authorMcCabe, Matthewen
dc.contributor.authorEvans, Jason P.en
dc.contributor.authorStisen, Simonen
dc.date.accessioned2015-05-04T16:36:28Zen
dc.date.available2015-05-04T16:36:28Zen
dc.date.issued2014-03en
dc.identifier.citationAssessing the impact of model spin-up on surface water-groundwater interactions using an integrated hydrologic model 2014, 50 (3):2636 Water Resources Researchen
dc.identifier.issn00431397en
dc.identifier.doi10.1002/2013WR014258en
dc.identifier.urihttp://hdl.handle.net/10754/552178en
dc.description.abstractIntegrated land surface-groundwater models are valuable tools in simulating the terrestrial hydrologic cycle as a continuous system and exploring the extent of land surface-subsurface interactions from catchment to regional scales. However, the fidelity of model simulations is impacted not only by the vegetation and subsurface parameterizations, but also by the antecedent condition of model state variables, such as the initial soil moisture, depth to groundwater, and ground temperature. In land surface modeling, a given model is often run repeatedly over a single year of forcing data until it reaches an equilibrium state: the point at which there is minimal artificial drift in the model state or prognostic variables (most often the soil moisture). For more complex coupled and integrated systems, where there is an increased computational cost of simulation and the number of variables sensitive to initialization is greater than in traditional uncoupled land surface modeling schemes, the challenge is to minimize the impact of initialization while using the smallest spin-up time possible. In this study, multicriteria analysis was performed to assess the spin-up behavior of the ParFlow.CLM integrated groundwater-surface water-land surface model over a 208 km2 subcatchment of the Ringkobing Fjord catchment in Denmark. Various measures of spin-up performance were computed for model state variables such as the soil moisture and groundwater storage, as well as for diagnostic variables such as the latent and sensible heat fluxes. The impacts of initial conditions on surface water-groundwater interactions were then explored. Our analysis illustrates that the determination of an equilibrium state depends strongly on the variable and performance measure used. Choosing an improper initialization of the model can generate simulations that lead to a misinterpretation of land surface-subsurface feedback processes and result in large biases in simulated discharge. Estimated spin-up time from a series of spin-up functions revealed that 20 (or 21) years of simulation were sufficient for the catchment to equilibrate according to at least one criterion at the 0.1% (0.01%) threshold level. Amongst a range of convergence metrics examined, percentage changes in monthly values of groundwater and unsaturated zone storages produced a slow system convergence to equilibrium, whereas criteria based on ground temperature allowed a more rapid spin-up. Slow convergence of unsaturated and saturated zone storages is a result of the dynamic adjustment of the water table in response to a physically arbitrary or inconsistent initialization of a spatially uniform water table. Achieving equilibrium in subsurface storage ensured equilibrium across a spectrum of other variables, hence providing a good measure of system-wide equilibrium. Overall, results highlight the importance of correctly identifying the key variable affecting model equilibrium and also the need to use a multicriteria approach to achieve a rapid and stable model spin-up.en
dc.relation.urlhttp://doi.wiley.com/10.1002/2013WR014258en
dc.rightsArchived with thanks to Water Resources Researchen
dc.titleAssessing the impact of model spin-up on surface water-groundwater interactions using an integrated hydrologic modelen
dc.typeArticleen
dc.contributor.departmentWater Desalination and Reuse Research Center (WDRC)en
dc.identifier.journalWater Resources Researchen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionSchool of Civil and Environmental Engineering; University of New South Wales; Sydney New South Wales Australiaen
dc.contributor.institutionClimate Change Research Centre; University of New South Wales; Sydney New South Wales Australiaen
dc.contributor.institutionGeological Survey of Denmark and Greenland; Copenhagen Denmarken
dc.contributor.institutionConnected Waters Initiative Research Centre, University of New South Wales, Sydney, New South Wales, Australiaen
dc.contributor.institutionARC Centre of Excellence for Climate System Science, University of New South Wales, Sydney, New South Wales, Australiaen
kaust.authorMcCabe, Matthewen
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