Abstract
Abstract Due to the spatial heterogeneity, the hydrological model calibration results only at the total outlet of the basin may not represent the whole basin. To more accurately simulate the historical streamflow process within the Qujiang River Basin, we set up three calibration strategies (single-site, S1; multisite simultaneous, S2; and multisite sequential, S3) for four hydrological stations based on the SWAT (Soil and Water Assessment Tool) model driven by CMADS (China Meteorological Assimilation Driving Datasets for the SWAT model). In addition, the implications of these calibration issues are extended to future streamflow projections using multimodel ensemble data in CMIP6 (Coupled Model Intercomparison Project Phase 6). In the model calibration phase, the SWAT model achieved very satisfactory results in the study area. Compared with S1 and S2, S3 can effectively improve the accuracy of streamflow simulation of stations within the basin and reduce the simulation deviation. Especially at the daily scale, the average NSE values of the four stations with S3 increased by 0.26 and 0.07, and the overall deviation decreased by 0.25 and 6.43%, respectively. Parameter sensitivity analysis also shows that spatial heterogeneity can be more adequately considered when using S3 to calibrate the model. As for the results of future streamflow projection, when using the S3, the average annual streamflow of four stations in the three climate scenarios from 2021 to 2050 is about 44.21, 130.00, 321.55 and 713.24 m3/s, respectively. Correspondingly, the use of S1 and S2 would bring certain risks to future water resource management.
Highlights
As an important tool to analyze the hydrological process of a river basin, the hydrological models have shown very strong capabilities in solving many problems such as water resource planning, flood control and disaster reduction, and nonpoint source pollution in recent decades (Boufala et al 2019; Wang et al 2019; Mahmoodi et al 2020; Rudra et al 2020)
The second aspect is to extend the research of multisite calibration strategy to the future period and use the latest updated CMIP6 data, which can provide a certain reference for the contents of related fields
Based on the SWAT model driven by CMADS, in this study, we set up single-site calibration, multisite simultaneous calibration and multisite sequential calibration strategies using four hydrological stations in the Qujiang River Basin
Summary
As an important tool to analyze the hydrological process of a river basin, the hydrological models have shown very strong capabilities in solving many problems such as water resource planning, flood control and disaster reduction, and nonpoint source pollution in recent decades (Boufala et al 2019; Wang et al 2019; Mahmoodi et al 2020; Rudra et al 2020). The SWAT model can divide the basin into different units by the underlying surface attributes for simulation, considering that each sub-basin in a large basin has different hydrological characteristics, the heterogeneity for the spatial attributes of the basin should be. The implications of different calibration strategies on streamflow projections in the context of climate change have been rarely mentioned in multisite calibration studies of distributed hydrological models, especially using CMIP6 data. Based on the CMADS-driven SWAT model, the study attempts to explore two aspects: (1) performance discrepancy of single-site calibration and multisite calibration strategies in simulating the hydrological process of Qujiang River Basin and (2) the influence of different strategies on future streamflow prediction with multimodel ensemble data in CMIP6. The second aspect is to extend the research of multisite calibration strategy to the future period and use the latest updated CMIP6 data, which can provide a certain reference for the contents of related fields
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