Respond to comment 2_A 439-year simulated daily discharge dataset (1861-2299) for the upper Yangtze River

Abstract. The outputs of four global climate models (GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR and MIROC5), which were statistically downscaled and bias corrected, were used to drive four hydrological models (Hydrologiska Byråns, HBV; Soil and Water Assessment Tool, SWAT; Soil and Water Integrated Model, SWIM; and Variable Infiltration Capacity, VIC) to simulate the daily discharge at the Cuntan hydrological station in the upper Yangtze River from 1861 to 2299. As the performances of hydrological models in various climate conditions could be different, the models were first calibrated in the period from 1979 to 1990. Then, the models were validated in the comparatively wet period, 1967–1978, and in the comparatively dry period, 1991–2002. A multi-objective automatic calibration programme using a univariate search technique was applied to find the optimal parameter set for each of the four hydrological models. The Nash–Sutcliffe efficiency (NSE) of daily discharge and the weighted least-squares function (WLS) of extreme discharge events, represented by high flow (Q10) and low flow (Q90), were included in the objective functions of the parameterization process. In addition, the simulated evapotranspiration results were compared with the GLEAM evapotranspiration data for the upper Yangtze River basin. For evaluating the performances of the hydrological models, the NSE, modified Kling–Gupta efficiency (KGE), ratio of the root-mean-square error to the standard deviation of the measured data (RSR) and Pearson's correlation coefficient (r) were used. The four hydrological models reach satisfactory simulation results in both the calibration and validation periods. In this study, the daily discharge is simulated for the upper Yangtze River under the preindustrial control (piControl) scenario without anthropogenic climate change from 1861 to 2299 and for the historical period 1861–2005 and for 2006 to 2299 under the RCP2.6, RCP4.5, RCP6.0 and RCP8.5 scenarios. The long-term daily discharge dataset can be used in the international context and water management, e.g. in the framework of Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) by providing clues to what extent human-induced climate change could impact streamflow and streamflow trend in the future. The datasets are available at: https://doi.org/10.4121/uuid:8658b22a-8f98-4043-9f8f-d77684d58cbc (Gao et al., 2019).

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Respond to comment 1_A 439-year simulated daily discharge dataset (1861-2299) for the upper Yangtze River

10.5194/essd-2019-89-ac2 ◽

2019 ◽

Author(s):

Chao Gao

Keyword(s):

Yangtze River ◽

Upper Yangtze River ◽

Daily Discharge ◽

The Upper Yangtze River

Download Full-text

A 439-year daily discharge dataset (1861–2299) for the upper Yangtze River, China

10.5194/essd-2019-89 ◽

2019 ◽

Author(s):

Chao Gao ◽

Buda Su ◽

Valentina Krysanova ◽

Qianyu Zha ◽

Cai Chen ◽

...

Keyword(s):

Climate Change ◽

Yangtze River ◽

Weighted Least Squares ◽

Global Climate Models ◽

Low Flow ◽

Historical Period ◽

Hydrological Models ◽

Upper Yangtze River ◽

Daily Discharge ◽

The Upper Yangtze River

Abstract. The outputs of four Global Climate Models (GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR and MIROC5), which were statistically downscaled and bias corrected, were used to drive four hydrological models (HBV, SWAT, SWIM and VIC) to simulate the daily discharge at the Cuntan hydrological station in the upper Yangtze River from 1861 to 2299. As the performances of hydrological models in various climate conditions could be different, the models were first calibrated in the period from 1979 to 1990. Then, the models were validated in the wet period, 1967–1978, and in the dry period, 1991–2002. A multi-objective automatic calibration programme using a univariate search technique was applied to find the optimal parameter sets for each of the four hydrological models. The Nash-Sutcliffe efficiency (NSE) of daily discharge and the weighted least squares function (WLS) of extreme discharge events, represented by high flow (Q10) and low flow (Q90), were included in the objective functions of the parameterization process. In addition, the simulated evapotranspiration results were compared with evapotranspiration data from the GLEAM project for the upper Yangtze basin. For evaluating the performances of the hydrological models, the NSE, modified Kling-Gupta efficiency (KGE), ratio of the root mean square error to the standard deviation of the measured data (RSR) and Pearson's correlation coefficient (r) were used. The four hydrological models showed good performance in the calibration and validation periods. In this study, the daily runoff was simulated for the upper Yangtze River under the preindustrial control (piControl) scenario without anthropogenic climate change, from 1861–2299, for the historical period 1861–2005, and under the RCP2.6, RCP4.5, RCP6.0 and RCP8.5 scenarios in the period from 2006 to 2299. The long-term daily discharge datasets for the upper Yangtze River provide streamflow trends in the future and clues regarding to what extent human-induced climate change could impact streamflow. The datasets are available at the https://doi.org/10.4121/uuid:8658b22a-8f98-4043-9f8f-d77684d58cbc website.

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