Hydropedological Classification of South African Hillslopes

Abstract

Soil has an interactive relationship with hydrology. It is a product of water related processes (physical and chemical) and a first order control of the destiny of rainwater. It is mapable with transfer functionality. These properties make it an appropriate entity for classification of hillslope hydrological responses. Hillslopes from all over South Africa were surveyed and hydropedologically interpreted. Soils were classified and based on the interpretation of the dominant hydrological pathway grouped into five hydrological soil types. The type and position of a hydrological soil types in a hillslope served as basis for the hillslope classification. Each of the hillslopes surveyed were assigned to one of six hillslopes classes. A flow diagram of the hydrology is presented. Arrows indicate the dominant flowpaths, and a hydrograph shows the anticipated impact on streamflow. The results made an impact on distributed modeling and land‐use decisions, including land‐use change to forestry and selection of on‐site sanitation limiting water pollution. The composition and distribution of hydrological hillslope classes can serve as a basis for classification of catchments.

Creating a conceptual hydrological soil response map for the Stevenson Hamilton Research Supersite, Kruger National Park, South Africa

“…The SMUs were grouped on the basis of hydrological response (Van Tol et al, 2013). This also meant that observations of the same soil form could be included into different CHSRUs, such as the Bonheim soil form which fits into both the Clayey Interflow and Clayey Recharge classes.…”

“…To create a hydrological soil map, a CHSR was assigned to each SMU according to Van Tol et al (2013). Thus the hydrological soil map is a spatial representation of the CHSR of the study area, based on the distribution of the SMUs.…”

“…Recharge soils are defined as soils where the dominant water flow path is one where the free water leaves the evapotranspiration zone, and recharges the lower vadoze zone. Interflow soils are soils where the dominant flow path is where free water flows laterally within the upper and intermediate vadoze zone, while responsive soils refer to soils where the dominant flow path is overland flow, due to either shallow soils with limited storage capacity or soils saturated with water for long periods (Van Tol et al, 2013).…”

Hydropedology and the Societal Challenge of Realizing the 2015 United Nations Sustainable Development Goals

“…Introducing hydropedology as a means to stimulate interaction between the two groups of scientists has therefore been valuable and also quite successful (Vogel et al, 2013;Lin et al, 2015). Overall, much emphasis is on innovative field measurements, while pedological input appears to be somewhat limited, with notable exceptions (e.g., van Tol et al, 2013).…”

Spatial soil information in South Africa: Situational analysis, limitations and challenges

“…Interpretation of soil properties can therefore serve as an indicator of the dominant hydrological processes 35,36 and assist in the structuring and configuration of hydrological models. 37 Hydrologists agree that soil properties and their spatial variation should be captured in hydrological models for accurate water quantity and quality predictions and estimation of the hydrologic sensitivity of the land to change 38,39 , but they generally lack the skill to gather and interpret soil information 40,41 . New generation soil information could alter this perception.…”