Mapping (dis)agreement in hydrologic projections

Journal article (2018)

Authors

L. A. Melsen Wageningen University & Research
Nans Addor University Corporation for Atmospheric Research, University of East Anglia
Naoki Mizukami University Corporation for Atmospheric Research
Andrew J. Newman University Corporation for Atmospheric Research
P. J. J. F. Torfs Wageningen University & Research
Martyn P. Clark University Corporation for Atmospheric Research
R. Uijlenhoet Wageningen University & Research
Adriaan J. Teuling Wageningen University & Research
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Published Date

2018

Language

English

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Abstract

Hydrologic projections are of vital socio-economic importance. However, they are also prone to uncertainty. In order to establish a meaningful range of storylines to support water managers in decision making, we need to reveal the relevant sources of uncertainty. Here, we systematically and extensively investigate uncertainty in hydrologic projections for 605 basins throughout the contiguous US. We show that in the majority of the basins, the sign of change in average annual runoff and discharge timing for the period 2070-2100 compared to 1985-2008 differs among combinations of climate models, hydrologic models, and parameters. Mapping the results revealed that different sources of uncertainty dominate in different regions. Hydrologic model induced uncertainty in the sign of change in mean runoff was related to snow processes and aridity, whereas uncertainty in both mean runoff and discharge timing induced by the climate models was related to disagreement among the models regarding the change in precipitation. Overall, disagreement on the sign of change was more widespread for the mean runoff than for the discharge timing. The results demonstrate the need to define a wide range of quantitative hydrologic storylines, including parameter, hydrologic model, and climate model forcing uncertainty, to support water resource planning.