Examining the value of hydropedological information on hydrological modeling at different scales in the Sabie catchment, South Africa

Abstract

Detailed soil information is increasingly sought after for watershed‐scale hydrological modeling to better understand the soil–water interactions at a landscape level. In South Africa, 8% of the surface area is responsible for 50% of the mean annual runoff. Thus, understanding the soil–water dynamics in these catchments remains imperative to future water resource management. In this study, the value of hydropedological information is tested by comparing a detailed hydropedological map based on infield soil information to the best readily available soil information at five different catchment sizes (48, 56, 174, 674, and 2421 km2) using the soil and water assessment tool (SWAT)+ model in the Sabie catchment, South Africa. The aim was to determine the value of hydropedological information at different scales as well as illustrate the value of hydropedology as soft data to improve hydrological process representation. Improved hydropedological information significantly improved long‐term streamflow simulations at all catchment sizes, except for the largest catchment (2421 km2). It is assumed that the resulting improved streamflow simulations are a direct result of the improved hydrological process representation achieved by the hydropedological information. Here, we argue that hydropedological information should form an important soft data tool to better understand and simulate different hydrological processes.

Model calibration using hydropedological insights to improve the simulation of internal hydrological processes using SWAT+

“…The SWAT+ model had the exact same setup as used in Smit et al 7). These results are an improvement on the uncalibrated model, which achieved satisfactory R 2 at only three of the five catchments, namely, X3H003, X3H001, and X3H024 with values of 0.66, 0.67, and 0.71, respectively (Smit et al, 2023a).…”

“…Manipulating and calibrating major hydrological processes such as surface runoff, lateral flow and percolation remains imperative to accurately modelling water resources throughout a landscape. The uncalibrated SWAT+ model (Smit et al, 2023a) illustrated that the hydrological soil types within the catchment did not necessarily accurately reflect the dominant hydrological process associated with each soil mapping unit, such as Interflow soils not simulating sufficient lateral flow volumes and Recharge Shallow soils primarily contributing surface runoff volumes, with limited percolation contributions.…”

Vadose Zone Journal Special Section: Soil physics in agricultural production, water resources, and waste management

“…

It aimed to receive contributions about applications of soil physics and how they increase our understanding of agricultural production, water resources, and waste management.The conference took place in South Africa, and the focus on African scenarios was considered as reflected in some of the nine papers published in this special section. In fact, three of the publications (Hendrickx et al, 2023;Kibirige et al, 2023;Smit et al, 2023) describe modeling and measurement efforts in catchments in South Africa. The paper by Bouma (2023), a keynote speaker at the conference, also partly focuses on the African reality.Catchment hydrology and hydropedology are the specific focus of three of the papers published in this section.

…”

“…The conference took place in South Africa, and the focus on African scenarios was considered as reflected in some of the nine papers published in this special section. In fact, three of the publications (Hendrickx et al, 2023;Kibirige et al, 2023;Smit et al, 2023) describe modeling and measurement efforts in catchments in South Africa. The paper by Bouma (2023), a keynote speaker at the conference, also partly focuses on the African reality.…”

“…Smit et al. (2023) analyze how hydropedological information can be used to improve the understanding and modeling of hydrological processes at the catchment scale. Kibirige et al.…”