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Identification of Time-varying Parameters of a Monthly Budyko Function and its Implications
  • +2
  • Weibo Liu,
  • Pan Liu,
  • Lei Cheng,
  • Xiaojing Zhang,
  • Liting Zhou
Weibo Liu
State Key Laboratory of Water Resources and Hydropower Engineering Science
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Pan Liu
State Key Laboratory of Water Resources and Hydropower Engineering Science
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Lei Cheng
State Key Laboratory of Water Resources and Hydropower Engineering Science
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Xiaojing Zhang
State Key Laboratory of Water Resources and Hydropower Engineering Science
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Liting Zhou
State Key Laboratory of Water Resources and Hydropower Engineering Science
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Abstract

The Budyko framework, which can describe a simple but useful partitioning of precipitation under supply and energy limits, is used widely to estimate evapotranspiration (ET). Previous studies have investigated time-variant Budyko functions on annual or interannual scales but seldom on the intra-annual scale. This study used a monthly two-parameter ( κ and y0) Budyko function and three schemes that considered single observations (ET or streamflow (Q)) and dual observations (ET and Q) to assimilate the time-varying parameters using the ensemble Kalman filter method. The study considered the contiguous USA (CONUS) using the Model Parameter Estimation Experiment dataset. The time-varying parameters were explained on the basis of time series analysis and correlation with meteorological data. Three conclusions were as follows. (1) The identified time-varying parameters ( κ and y0) of the Budyko function could effectively simulate ET. (2) The assimilation using only ET observations could identify a plausible set for parameter κ but was inadequate for y0 . (3) Most time-varying parameters exhibited a 12-month period, and the trend and change points detected for Midwest CONUS were related to anthropogenic influences such as extraction and use of groundwater. The findings show that changing environment can be detected by using the proposed time-varying parameters of the Budyko function.

Peer review status:UNDER REVIEW

05 Apr 2021Submitted to Hydrological Processes
07 Apr 2021Assigned to Editor
07 Apr 2021Submission Checks Completed
08 Apr 2021Reviewer(s) Assigned