Identification of time-varying parameters of a monthly Budyko function in US MOPEX catchments and its implications

Study region: Model Parameter Estimation Experiment (MOPEX) catchments across the continental United States. Study focus: The Budyko framework provides a simple yet useful method for estimating evapotranspiration (ET), traditionally used at the mean annual scale due to the assumption of constant cat...

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Main Authors: Weibo Liu, Pan Liu, Lei Cheng, Xiaojing Zhang, Liting Zhou
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Journal of Hydrology: Regional Studies
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Online Access:http://www.sciencedirect.com/science/article/pii/S2214581825001739
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author Weibo Liu
Pan Liu
Lei Cheng
Xiaojing Zhang
Liting Zhou
author_facet Weibo Liu
Pan Liu
Lei Cheng
Xiaojing Zhang
Liting Zhou
author_sort Weibo Liu
collection DOAJ
description Study region: Model Parameter Estimation Experiment (MOPEX) catchments across the continental United States. Study focus: The Budyko framework provides a simple yet useful method for estimating evapotranspiration (ET), traditionally used at the mean annual scale due to the assumption of constant catchment water storage. Under changing conditions, time-invariant model parameters may not fully capture variations in the underlying surface. Several studies have extended the Budyko framework to the monthly scale; however, few studies have identified monthly time-varying Budyko model parameters and explored the factors driving their variability. This study develops a method for identifying time-varying parameters κ and y0 of a two-parameter Budyko model using the Ensemble Kalman Filter. Additionally, Extreme Gradient Boosting is used to explore the factors influencing time-varying parameters. New hydrological insights for the study region: Monthly time-varying parameters are effectively identified through simultaneous assimilation of ET and runoff observations, achieving a Kling-Gupta Efficiency of 0.94 in ET simulation. (2) 11 and 2 catchments display change points and trends in parameter κ, respectively, while 64 and 48 catchments exhibit change points and trends in y0, respectively. (3) Parameter κ is mainly influenced by climatic factors in low-latitude, storage-related factors in high-latitude, and normalized difference vegetation index in central U.S. catchments, respectively. y0 is mainly influenced by total soil moisture, along with vegetation and agricultural land cover changes in the central region.
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publishDate 2025-06-01
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series Journal of Hydrology: Regional Studies
spelling doaj-art-1cf617ec943b4f949b1c4261bdac3f122025-08-20T03:47:32ZengElsevierJournal of Hydrology: Regional Studies2214-58182025-06-015910234810.1016/j.ejrh.2025.102348Identification of time-varying parameters of a monthly Budyko function in US MOPEX catchments and its implicationsWeibo Liu0Pan Liu1Lei Cheng2Xiaojing Zhang3Liting Zhou4State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Key Lab of Water System Science for Sponge City Construction, Wuhan University, Wuhan 430072, China; Research Institute for Water Security (RIWS), Wuhan University, Wuhan 430072, ChinaState Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Key Lab of Water System Science for Sponge City Construction, Wuhan University, Wuhan 430072, China; Research Institute for Water Security (RIWS), Wuhan University, Wuhan 430072, China; Corresponding author at: State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China.State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Key Lab of Water System Science for Sponge City Construction, Wuhan University, Wuhan 430072, China; Research Institute for Water Security (RIWS), Wuhan University, Wuhan 430072, ChinaState Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Key Lab of Water System Science for Sponge City Construction, Wuhan University, Wuhan 430072, China; Research Institute for Water Security (RIWS), Wuhan University, Wuhan 430072, ChinaChina Yangtze Power Co., Ltd., Yichang 443133, China; Hubei Key Laboratory of Intelligent Yangtze and Hydroelectric Science, Yichang 443133, ChinaStudy region: Model Parameter Estimation Experiment (MOPEX) catchments across the continental United States. Study focus: The Budyko framework provides a simple yet useful method for estimating evapotranspiration (ET), traditionally used at the mean annual scale due to the assumption of constant catchment water storage. Under changing conditions, time-invariant model parameters may not fully capture variations in the underlying surface. Several studies have extended the Budyko framework to the monthly scale; however, few studies have identified monthly time-varying Budyko model parameters and explored the factors driving their variability. This study develops a method for identifying time-varying parameters κ and y0 of a two-parameter Budyko model using the Ensemble Kalman Filter. Additionally, Extreme Gradient Boosting is used to explore the factors influencing time-varying parameters. New hydrological insights for the study region: Monthly time-varying parameters are effectively identified through simultaneous assimilation of ET and runoff observations, achieving a Kling-Gupta Efficiency of 0.94 in ET simulation. (2) 11 and 2 catchments display change points and trends in parameter κ, respectively, while 64 and 48 catchments exhibit change points and trends in y0, respectively. (3) Parameter κ is mainly influenced by climatic factors in low-latitude, storage-related factors in high-latitude, and normalized difference vegetation index in central U.S. catchments, respectively. y0 is mainly influenced by total soil moisture, along with vegetation and agricultural land cover changes in the central region.http://www.sciencedirect.com/science/article/pii/S2214581825001739Evapotranspiration estimationMonthly Budyko functionTime-varying parametersEnsemble Kalman filterMOPEX catchments
spellingShingle Weibo Liu
Pan Liu
Lei Cheng
Xiaojing Zhang
Liting Zhou
Identification of time-varying parameters of a monthly Budyko function in US MOPEX catchments and its implications
Journal of Hydrology: Regional Studies
Evapotranspiration estimation
Monthly Budyko function
Time-varying parameters
Ensemble Kalman filter
MOPEX catchments
title Identification of time-varying parameters of a monthly Budyko function in US MOPEX catchments and its implications
title_full Identification of time-varying parameters of a monthly Budyko function in US MOPEX catchments and its implications
title_fullStr Identification of time-varying parameters of a monthly Budyko function in US MOPEX catchments and its implications
title_full_unstemmed Identification of time-varying parameters of a monthly Budyko function in US MOPEX catchments and its implications
title_short Identification of time-varying parameters of a monthly Budyko function in US MOPEX catchments and its implications
title_sort identification of time varying parameters of a monthly budyko function in us mopex catchments and its implications
topic Evapotranspiration estimation
Monthly Budyko function
Time-varying parameters
Ensemble Kalman filter
MOPEX catchments
url http://www.sciencedirect.com/science/article/pii/S2214581825001739
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