Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/hess-2017-90
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
06 Mar 2017
Review status
This discussion paper is under review for the journal Hydrology and Earth System Sciences (HESS).
Moment-based Metrics for Global Sensitivity Analysis of Hydrological Systems
Aronne Dell'Oca1, Monica Riva1,2, and Alberto Guadagnini1,2 1Dipartimento di Ingegneria Civile e Ambientale (DICA), Politecnico di Milano, Piazza L. Da Vinci, 32, 20133 Milano, Italy
2Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, Arizona, USA
Abstract. We propose new metrics to assist global sensitivity analysis, GSA, of hydrological and Earth systems. Our approach allows assessing the impact of uncertain parameters on main features of the probability density function, pdf, of a target model output, y. These include the expected value of y, the spread around the mean and the degree of symmetry and tailedness of the pdf of y. Since reliable assessment of higher order statistical moments can be computationally demanding, we couple our GSA approach with a surrogate model, approximating the full model response at a reduced computational cost. Here, we consider the generalized Polynomial Chaos Expansion (gPCE), other model reduction techniques being fully compatible with our theoretical framework. We demonstrate our approach through three test cases, including an analytical benchmark, a simplified scenario mimicking pumping in a coastal aquifer, and a laboratory-scale conservative transport experiment. Our results allow ascertaining which parameters can impact some moments of the model output pdf while being uninfluential to others. We also investigate the error associated with the evaluation of our sensitivity metrics by replacing the original system model through a gPCE. Our results indicate that the construction of a surrogate model with increasing level of accuracy might be required depending on the statistical moment considered in the GSA. Our approach is fully compatible with (and can assist the development of) analysis techniques employed in the context of reduction of model complexity, model calibration, design of experiment, uncertainty quantification and risk assessment.

Citation: Dell'Oca, A., Riva, M., and Guadagnini, A.: Moment-based Metrics for Global Sensitivity Analysis of Hydrological Systems, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2017-90, in review, 2017.
Aronne Dell'Oca et al.
Aronne Dell'Oca et al.
Aronne Dell'Oca et al.

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Short summary
We propose new metrics to assist global sensitivity analysis of Earth systems. Our approach allows assessing the impact of model parameters on the first four statistical moments of a target model output, allowing to ascertain which parameters can affect some moments of the model output pdf while being uninfluential to others. Our approach is fully compatible with analysis in the context of model complexity reduction, design of experiment, uncertainty quantification and risk assessment.
We propose new metrics to assist global sensitivity analysis of Earth systems. Our approach...
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