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How do hydrologic modeling decisions affect the portrayal of climate change impacts?
Author(s) -
Mendoza Pablo A.,
Clark Martyn P.,
Mizukami Naoki,
Gutmann Ethan D.,
Arnold Jeffrey R.,
Brekke Levi D.,
Rajagopalan Balaji
Publication year - 2015
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.10684
Subject(s) - climate change , environmental science , hydrological modelling , parametric statistics , calibration , water balance , range (aeronautics) , parameter space , drainage basin , forcing (mathematics) , climate model , parametric model , magnitude (astronomy) , hydrology (agriculture) , computer science , econometrics , climatology , statistics , mathematics , geology , geography , oceanography , materials science , geotechnical engineering , cartography , composite material , physics , astronomy
Abstract End users face a range of subjective decisions when evaluating climate change impacts on hydrology, but the importance of these decisions is rarely assessed. In this paper, we evaluate the implications of hydrologic modelling choices on projected changes in the annual water balance, monthly simulated processes, and signature measures (i.e. metrics that quantify characteristics of the hydrologic catchment response) under a future climate scenario. To this end, we compare hydrologic changes computed with four different model structures – whose parameters have been obtained using a common calibration strategy – with hydrologic changes computed with a single model structure and parameter sets from multiple options for different calibration decisions (objective function, local optima, and calibration forcing dataset). Results show that both model structure selection and the parameter estimation strategy affect the direction and magnitude of projected changes in the annual water balance, and that the relative effects of these decisions are basin dependent. The analysis of monthly changes illustrates that parameter estimation strategies can provide similar or larger uncertainties in simulations of some hydrologic processes when compared with uncertainties coming from model choice. We found that the relative effects of modelling decisions on projected changes in catchment behaviour depend on the signature measure analysed. Furthermore, parameter sets with similar performance, but located in different regions of the parameter space, provide very different projections for future catchment behaviour. More generally, the results obtained in this study prompt the need to incorporate parametric uncertainty in multi‐model frameworks to avoid an over‐confident portrayal of climate change impacts. Copyright © 2015 John Wiley & Sons, Ltd.