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Model calibration using hydropedological insights to improve internal hydrological processes within SWAT+
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  • I.E. Smit,
  • G.M. Van Zijl,
  • E.S. Riddell,
  • Johan van Tol
I.E. Smit
University of the Free State

Corresponding Author:[email protected]

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G.M. Van Zijl
North-West University Unit for Environmental Sciences and Management
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E.S. Riddell
University of KwaZulu-Natal
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Johan van Tol
University of the Free State
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Abstract

Soils affect the distribution of hydrological processes by partitioning precipitation into different components of the water balance. Therefore, understanding soil-water dynamics at a catchment scale remains imperative to future water resource management. In this study the value of hydropedological insights to calibrate a processes based model. Soil morphology was used as soft data to assist in the calibration of the SWAT+ model at five different catchment sizes (48 km 2, 56 km 2, 174 km 2, 674 km 2 and 2421 km 2) in the Sabie River catchment, South Africa. The aim of this study was to calibrate the SWAT+ model to accurately simulate long-term monthly streamflow predictions as well as to reflect internal soil hydrological processes using a procedure focusing on hydropedology as a calibration tool in a multigauge system. Results indicated that calibration improved streamflow predictions where R 2 and Nash-Sutcliffe Efficiency (NSE) improved substantially, R 2 improved by 2 to 8% and NSE from negative correlations to values exceeding 0.5 at four of the five catchment scales compared to the uncalibrated model. Results confirm that soil mapping units can be calibrated individually within SWAT+ to improve the representation of hydrological processes. Particularly, the spatial linkage between hydropedology and hydrological processes, which is captured within the soil map of the catchment, can be adequately reflected within the model structure after calibration. This research should lead to an improved understanding of hydropedology as soft data to improve hydrological modelling accuracy.
06 Nov 2023Submitted to Hydrological Processes
07 Nov 2023Assigned to Editor
07 Nov 2023Submission Checks Completed
08 Nov 2023Reviewer(s) Assigned
08 Nov 2023Reviewer(s) Assigned