Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 20, 3245-3261, 2016
http://www.hydrol-earth-syst-sci.net/20/3245/2016/
doi:10.5194/hess-20-3245-2016
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
10 Aug 2016
Sensitivity of future continental United States water deficit projections to general circulation models, the evapotranspiration estimation method, and the greenhouse gas emission scenario
Seungwoo Chang1, Wendy D. Graham1,2, Syewoon Hwang3, and Rafael Muñoz-Carpena4 1Department of Agricultural and Biological Engineering, University of Florida, 570 Weil Hall, P.O. Box 116601, Gainesville, FL 32611, USA
2Water Institute, University of Florida, 570 Weil Hall, P.O. Box 116601, Gainesville, FL 32611, USA
3Department of Agricultural Engineering, Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 660-701, South Korea
4Department of Agricultural and Biological Engineering, University of Florida, 287 Frazier Rogers Hall, P.O. Box 110570, Gainesville, FL 32611, USA
Abstract. Projecting water deficit under various possible future climate scenarios depends on the choice of general circulation model (GCM), reference evapotranspiration (ET0) estimation method, and Representative Concentration Pathway (RCP) trajectory. The relative contribution of each of these factors must be evaluated in order to choose an appropriate ensemble of future scenarios for water resources planning. In this study variance-based global sensitivity analysis and Monte Carlo filtering were used to evaluate the relative sensitivity of projected changes in precipitation (P), ET0, and water deficit (defined here as P–ET0) to choice of GCM, ET0 estimation method, and RCP trajectory over the continental United States (US) for two distinct future periods: 2030–2060 (future period 1) and 2070–2100 (future period 2). A total of 9 GCMs, 10 ET0 methods, and 3 RCP trajectories were used to quantify the range of future projections and estimate the relative sensitivity of future projections to each of these factors. In general, for all regions of the continental US, changes in future precipitation are most sensitive to the choice of GCM, while changes in future ET0 are most sensitive to the choice of ET0 estimation method. For changes in future water deficit, the choice of GCM is the most influential factor in the cool season (December–March), and the choice of ET0 estimation method is most important in the warm season (May–October) for all regions except the Southeast US, where GCMs and ET0 have approximately equal influence throughout most of the year. Although the choice of RCP trajectory is generally less important than the choice of GCM or ET0 method, the impact of RCP trajectory increases in future period 2 over future period 1 for all factors. Monte Carlo filtering results indicate that particular GCMs and ET0 methods drive the projection of wetter or drier future conditions much more than RCP trajectory; however, the set of GCMs and ET0 methods that produce wetter or drier projections varies substantially by region. Results of this study indicate that, in addition to using an ensemble of GCMs and several RCP trajectories, a range of regionally relevant ET0 estimation methods should be used to develop a robust range of future conditions for water resources planning under climate change.

Citation: Chang, S., Graham, W. D., Hwang, S., and Muñoz-Carpena, R.: Sensitivity of future continental United States water deficit projections to general circulation models, the evapotranspiration estimation method, and the greenhouse gas emission scenario, Hydrol. Earth Syst. Sci., 20, 3245-3261, doi:10.5194/hess-20-3245-2016, 2016.
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Short summary
Projecting water deficit depends on how researchers combine possible future climate scenarios such as general circulation models (GCMs), evapotranspiration estimation method (ET), and greenhouse gas emission scenarios. Using global sensitivity analysis, we found the relative contribution of each of these factors to projecting future water deficit and the choice of ET estimation method are as important as the choice of GCM, and greenhouse gas emission scenario is less influential than the others.
Projecting water deficit depends on how researchers combine possible future climate scenarios...
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