Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations

Human impacts increasingly affect the global hydrological cycle and indeed dominate hydrological changes in some regions. Hydrologists have sought to identify the human-impact-induced hydrological variations via parameterizing anthropogenic water uses in global hydrological models (GHMs). The conseq...

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Main Authors:	Liu, Xingcai, Tang, Qiuhong, Cui, Huijuan, Mu, Mengfei, Gerten, Dieter, Gosling, Simon N., Masaki, Yoshimitsu, Satoh, Yusuke, Wada, Yoshihide
Format:	Article
Language:	English
Published:	IOP Publishing 2017
Online Access:	http://eprints.nottingham.ac.uk/42011/ http://eprints.nottingham.ac.uk/42011/ http://eprints.nottingham.ac.uk/42011/ http://eprints.nottingham.ac.uk/42011/1/Liu_2017_Environ._Res._Lett._12_025009.pdf

id	nottingham-42011
recordtype	eprints
spelling	nottingham-420112017-10-13T01:06:54Z http://eprints.nottingham.ac.uk/42011/ Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations Liu, Xingcai Tang, Qiuhong Cui, Huijuan Mu, Mengfei Gerten, Dieter Gosling, Simon N. Masaki, Yoshimitsu Satoh, Yusuke Wada, Yoshihide Human impacts increasingly affect the global hydrological cycle and indeed dominate hydrological changes in some regions. Hydrologists have sought to identify the human-impact-induced hydrological variations via parameterizing anthropogenic water uses in global hydrological models (GHMs). The consequently increased model complexity is likely to introduce additional uncertainty among GHMs. Here, using four GHMs, between-model uncertainties are quantified in terms of the ratio of signal to noise (SNR) for average river flow during 1971–2000 simulated in two experiments, with representation of human impacts (VARSOC) and without (NOSOC). It is the first quantitative investigation of between-model uncertainty resulted from the inclusion of human impact parameterizations. Results show that the between-model uncertainties in terms of SNRs in the VARSOC annual flow are larger (about 2% for global and varied magnitude for different basins) than those in the NOSOC, which are particularly significant in most areas of Asia and northern areas to the Mediterranean Sea. The SNR differences are mostly negative (-20% to 5%, indicating higher uncertainty) for basin-averaged annual flow. The VARSOC high flow shows slightly lower uncertainties than NOSOC simulations, with SNR differences mostly ranging from -20% to 20%. The uncertainty differences between the two experiments are significantly related to the fraction of irrigation areas of basins. The large additional uncertainties in VARSOC simulations introduced by the inclusion of parameterizations of human impacts raise the urgent need of GHMs development regarding a better understanding of human impacts. Differences in the parameterizations of irrigation, reservoir regulation and water withdrawals are discussed towards potential directions of improvements for future GHM development. We also discuss the advantages of statistical approaches to reduce the between-model uncertainties, and the importance of calibration of GHMs for not only better performances of historical simulations but also more robust and confidential future projections of hydrological changes under a changing environment. IOP Publishing 2017-02-08 Article PeerReviewed application/pdf en http://eprints.nottingham.ac.uk/42011/1/Liu_2017_Environ._Res._Lett._12_025009.pdf Liu, Xingcai and Tang, Qiuhong and Cui, Huijuan and Mu, Mengfei and Gerten, Dieter and Gosling, Simon N. and Masaki, Yoshimitsu and Satoh, Yusuke and Wada, Yoshihide (2017) Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations. Environmental Research Letters, 12 (2). 025009/1-025009/10. ISSN 1748-9326 http://iopscience.iop.org/article/10.1088/1748-9326/aa5a3a/ doi:10.1088/1748-9326/aa5a3a doi:10.1088/1748-9326/aa5a3a
repository_type	Digital Repository
institution_category	Local University
institution	University of Nottingham Malaysia Campus
building	Nottingham Research Data Repository
collection	Online Access
language	English
description	Human impacts increasingly affect the global hydrological cycle and indeed dominate hydrological changes in some regions. Hydrologists have sought to identify the human-impact-induced hydrological variations via parameterizing anthropogenic water uses in global hydrological models (GHMs). The consequently increased model complexity is likely to introduce additional uncertainty among GHMs. Here, using four GHMs, between-model uncertainties are quantified in terms of the ratio of signal to noise (SNR) for average river flow during 1971–2000 simulated in two experiments, with representation of human impacts (VARSOC) and without (NOSOC). It is the first quantitative investigation of between-model uncertainty resulted from the inclusion of human impact parameterizations. Results show that the between-model uncertainties in terms of SNRs in the VARSOC annual flow are larger (about 2% for global and varied magnitude for different basins) than those in the NOSOC, which are particularly significant in most areas of Asia and northern areas to the Mediterranean Sea. The SNR differences are mostly negative (-20% to 5%, indicating higher uncertainty) for basin-averaged annual flow. The VARSOC high flow shows slightly lower uncertainties than NOSOC simulations, with SNR differences mostly ranging from -20% to 20%. The uncertainty differences between the two experiments are significantly related to the fraction of irrigation areas of basins. The large additional uncertainties in VARSOC simulations introduced by the inclusion of parameterizations of human impacts raise the urgent need of GHMs development regarding a better understanding of human impacts. Differences in the parameterizations of irrigation, reservoir regulation and water withdrawals are discussed towards potential directions of improvements for future GHM development. We also discuss the advantages of statistical approaches to reduce the between-model uncertainties, and the importance of calibration of GHMs for not only better performances of historical simulations but also more robust and confidential future projections of hydrological changes under a changing environment.
format	Article
author	Liu, Xingcai Tang, Qiuhong Cui, Huijuan Mu, Mengfei Gerten, Dieter Gosling, Simon N. Masaki, Yoshimitsu Satoh, Yusuke Wada, Yoshihide
spellingShingle	Liu, Xingcai Tang, Qiuhong Cui, Huijuan Mu, Mengfei Gerten, Dieter Gosling, Simon N. Masaki, Yoshimitsu Satoh, Yusuke Wada, Yoshihide Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations
author_facet	Liu, Xingcai Tang, Qiuhong Cui, Huijuan Mu, Mengfei Gerten, Dieter Gosling, Simon N. Masaki, Yoshimitsu Satoh, Yusuke Wada, Yoshihide
author_sort	Liu, Xingcai
title	Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations
title_short	Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations
title_full	Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations
title_fullStr	Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations
title_full_unstemmed	Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations
title_sort	multimodel uncertainty changes in simulated river flows induced by human impact parameterizations
publisher	IOP Publishing
publishDate	2017
url	http://eprints.nottingham.ac.uk/42011/ http://eprints.nottingham.ac.uk/42011/ http://eprints.nottingham.ac.uk/42011/ http://eprints.nottingham.ac.uk/42011/1/Liu_2017_Environ._Res._Lett._12_025009.pdf
first_indexed	2018-09-06T13:17:05Z
last_indexed	2018-09-06T13:17:05Z
_version_	1610864211837059072

Multimodel uncertainty changes in simulated river flows induced by human impact parameterizations

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