Improved Streamflow Calibration of a Land Surface Model by the Choice of Objective Functions—A Case Study of the Nakdong River Watershed in the Korean Peninsula
Department of Civil Engineering, Yeungnam University, 280 Daehak-Ro, Gyeongsan 38541, Gyeongbuk, Korea
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Academic Editors: Haw Yen and Aleksey Sheshukov
Water 2021, 13(12), 1709; https://doi.org/10.3390/w13121709
Received: 20 May 2021 / Revised: 12 June 2021 / Accepted: 15 June 2021 / Published: 21 June 2021
(This article belongs to the Special Issue Watershed Hydrology and Water Quality: Emerging Environmental Issues and Novel Modeling Techniques)
Long-term streamflow simulations of the Land Surface Models (LSMs) are necessary for the comprehensive evaluation of hydrological responses to climate change. The high complexity and uncertainty in the LSM modelling require the model calibration to improve the simulation performance and stability. Objective functions are commonly used in the calibration process, and the choice of objective functions plays a crucial role in model performance identification. The Kling and Gupta Efficiency (KGE) has been widely used in the hydrological model calibration by the measure of the three components (variability, bias, and correlation) decomposed from the Nash and Sutcliffe Efficiency (NSE). However, there is a clear tendency of systematic errors in the peak flow and/or water balance of streamflow time series optimized by the KGE calibration when the correlation between simulations and observations is relatively low. For a more balanced optimal solution of the KGE, this study has proposed the adjusted KGE (aKGE) by substituting the normalized correlation score in the KGE. The proposed aKGE was assessed by long-term daily streamflow simulation results from the Common Land Model (CoLM) for the calibration (2000–2009) and validation (2010–2019) periods in the Nakdong River Watershed, Korea. The case study demonstrated that the aKGE calibration can improve the simulation performance of high flow and annual average flow with a slightly inferior correlation of flows compared with the KGE and NSE criteria.
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Keywords:
model calibration; objective function; Kling and Gupta efficiency; Nash and Sutcliffe efficiency; multiple criteria; land surface model; long-term streamflow
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MDPI and ACS Style
Lee, J.S.; Choi, H.I. Improved Streamflow Calibration of a Land Surface Model by the Choice of Objective Functions—A Case Study of the Nakdong River Watershed in the Korean Peninsula. Water 2021, 13, 1709. https://doi.org/10.3390/w13121709
AMA Style
Lee JS, Choi HI. Improved Streamflow Calibration of a Land Surface Model by the Choice of Objective Functions—A Case Study of the Nakdong River Watershed in the Korean Peninsula. Water. 2021; 13(12):1709. https://doi.org/10.3390/w13121709
Chicago/Turabian StyleLee, Jong S., and Hyun I. Choi 2021. "Improved Streamflow Calibration of a Land Surface Model by the Choice of Objective Functions—A Case Study of the Nakdong River Watershed in the Korean Peninsula" Water 13, no. 12: 1709. https://doi.org/10.3390/w13121709
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