Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 11, 1077-1092, 2018
https://doi.org/10.5194/gmd-11-1077-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.
Development and technical paper
23 Mar 2018
A hydrological emulator for global applications – HE v1.0.0
Yaling Liu1,2, Mohamad Hejazi1, Hongyi Li3, Xuesong Zhang1, and Guoyong Leng1 1Joint Global Change Research Institute, Pacific Northwest National Laboratory, 5825 University Research Court, College Park, MD 20740, USA
2Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA
3Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA
Abstract. While global hydrological models (GHMs) are very useful in exploring water resources and interactions between the Earth and human systems, their use often requires numerous model inputs, complex model calibration, and high computation costs. To overcome these challenges, we construct an efficient open-source and ready-to-use hydrological emulator (HE) that can mimic complex GHMs at a range of spatial scales (e.g., basin, region, globe). More specifically, we construct both a lumped and a distributed scheme of the HE based on the monthly abcd model to explore the tradeoff between computational cost and model fidelity. Model predictability and computational efficiency are evaluated in simulating global runoff from 1971 to 2010 with both the lumped and distributed schemes. The results are compared against the runoff product from the widely used Variable Infiltration Capacity (VIC) model. Our evaluation indicates that the lumped and distributed schemes present comparable results regarding annual total quantity, spatial pattern, and temporal variation of the major water fluxes (e.g., total runoff, evapotranspiration) across the global 235 basins (e.g., correlation coefficient r between the annual total runoff from either of these two schemes and the VIC is  > 0.96), except for several cold (e.g., Arctic, interior Tibet), dry (e.g., North Africa) and mountainous (e.g., Argentina) regions. Compared against the monthly total runoff product from the VIC (aggregated from daily runoff), the global mean Kling–Gupta efficiencies are 0.75 and 0.79 for the lumped and distributed schemes, respectively, with the distributed scheme better capturing spatial heterogeneity. Notably, the computation efficiency of the lumped scheme is 2 orders of magnitude higher than the distributed one and 7 orders more efficient than the VIC model. A case study of uncertainty analysis for the world's 16 basins with top annual streamflow is conducted using 100 000 model simulations, and it demonstrates the lumped scheme's extraordinary advantage in computational efficiency. Our results suggest that the revised lumped abcd model can serve as an efficient and reasonable HE for complex GHMs and is suitable for broad practical use, and the distributed scheme is also an efficient alternative if spatial heterogeneity is of more interest.
Citation: Liu, Y., Hejazi, M., Li, H., Zhang, X., and Leng, G.: A hydrological emulator for global applications – HE v1.0.0, Geosci. Model Dev., 11, 1077-1092, https://doi.org/10.5194/gmd-11-1077-2018, 2018.
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Short summary
This hydrologic emulator provides researchers with an easy way to investigate the variations in water budgets at any spatial scale of interest, with minimum requirements of effort, reasonable model predictability, and appealing computational efficiency. We expect it to have a profound influence on scientific endeavors in hydrological modeling and to excite the immediate interest of researchers working on climate impact assessments, uncertainty/sensitivity analysis, and integrated assessment.
This hydrologic emulator provides researchers with an easy way to investigate the variations in...
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