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Transferability of hydrological models and ensemble averaging methods between contrasting climatic periods

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posted on 25.11.2016 by Ciaran Broderick, Tom Matthews, Robert Wilby, Satish Bastola, Conor Murphy
Understanding hydrological model predictive capabilities under contrasting climate conditions enables more robust decision making. Using Differential Split Sample Testing (DSST), we analyze the performance of six hydrological models for 37 Irish catchments under climate conditions unlike those used for model training. Additionally, we consider four ensemble averaging techniques when examining interperiod transferability. DSST is conducted using 2/3 year noncontinuous blocks of (i) the wettest/driest years on record based on precipitation totals and (ii) years with a more/less pronounced seasonal precipitation regime. Model transferability between contrasting regimes was found to vary depending on the testing scenario, catchment, and evaluation criteria considered. As expected, the ensemble average outperformed most individual ensemble members. However, averaging techniques differed considerably in the number of times they surpassed the best individual model member. Bayesian Model Averaging (BMA) and the Granger-Ramanathan Averaging (GRA) method were found to outperform the simple arithmetic mean (SAM) and Akaike Information Criteria Averaging (AICA). Here GRA performed better than the best individual model in 51%–86% of cases (according to the Nash-Sutcliffe criterion). When assessing model predictive skill under climate change conditions we recommend (i) setting up DSST to select the best available analogues of expected annual mean and seasonal climate conditions; (ii) applying multiple performance criteria; (iii) testing transferability using a diverse set of catchments; and (iv) using a multimodel ensemble in conjunction with an appropriate averaging technique. Given the computational efficiency and performance of GRA relative to BMA, the former is recommended as the preferred ensemble averaging technique for climate assessment.

Funding

C.M. and C.B. acknowledge funding provided by the Irish Environmental Protection Agency under project 2014-CCRP-MS.16.

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

Water Resources Research

Volume

52

Issue

10

Pages

8343-8373

Citation

BRODERICK, C. ... et al, 2016. Transferability of hydrological models and ensemble averaging methods between contrasting climatic periods. Water Resources Research, 52 (10), pp. 8343-8373.

Publisher

© American Geophysical Union Publications

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date

05/10/2016

Publication date

2016-10-17

Copyright date

2016

Notes

An edited version of this paper was published by AGU. Copyright 2016 American Geophysical Union. To view the published open abstract, go to http://dx.doi.org/10.1002/2016WR018850

ISSN

0043-1397

eISSN

1944-7973

Language

en

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