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.

The behavior of a water table (WT) is important in understanding groundwater dynamics. Results are presented of a disproportionate response of a WT in two distinct transient pressure wave mechanisms that occurred during rainfall events of the 2000–2001 summer season and in two different hillslope zones in the Weatherley research catchment of South Africa. The first mechanism was a groundwater ridging pressure wave, which frequently occurred at the low‐lying wetland zone and when the capillary fringe was close to the ground surface. Results from this zone indicated that groundwater ridging WT responses were caused by rainfall events that had a threshold total rainfall of 10 mm, and the magnitude of the responses had a linear relationship with the peak rainfall intensities. The mechanism, which exhibited the characteristics of the Lisse effect (pneumatically pressurized WT response), occurred at an elevated zone of the catchment, where bedrock is overlain by a shallow soil profile and perched groundwater. This second mechanism was particularly evident during a rainfall event that occurred in the early part of the season. During this event, a peak rainfall intensity of 228 mm/h generated a pressure wave from the ground surface toward the WT, where it disproportionately elevated the hydraulic head in the groundwater by 106 cm of H2O at the toeslope and without groundwater recharge via the infiltration profile. A laboratory experiment was performed and verified that the second mechanism was the Lisse effect and that, as in the groundwater ridging, the capillary fringe played a significant role.

There is an interactive relationship between soil and hydrology. Identifying and interpreting soil properties active in this relationship can enhance our understanding of the hydrological behaviour of soils and the hillslopes in which they occur. This study was conducted in the Weatherley research catchment, South Africa, where a hillslope in the upper part of the catchment was selected for detailed study. Soil properties and their spatial distribution in the hillslope were interpreted and related to their predicted hydrological response. From these interpretations a conceptual model of hillslope hydrological behaviour was developed. Vertical drainage was considered to be dominant in the upper areas of the hillslope as indicated by the presence of freely-drained apedal soils. These soils recharge the mid-and lower slope. Soils showing clear indications of interflow (A/B and soil/bedrock interface) dominate on the midslope. The valley bottom is covered by gleyed soils which is an indication of long periods of saturation. These saturated conditions favour overland flow due to saturation impairing infiltration. The conceptual model was then evaluated using hydrometric measurements in the form of tensiometers and streamflow hydrographs. Results confirm the reliability of the model and accentuate the contribution that soil science can make to the science of hydrology.

Water plays a primary role in soil genesis and soil strongly influences hydrological processes (flowpaths, residence times and storage). Morphological soil properties serve as indicators of hillslope hydrological behaviour and can facilitate hydrological predictions. Three catchments in the Bedford district (B3, B4 and B5) were surveyed for hydropedological purposes and the observed soil indicators and related geological, topographical and vegetation features were interpreted. In B4 & B5 shallow soils are the dominant factor governing overland flow promoting short residence times. Deeper soils and fractured bedrock in B3 facilitate bedrock flow and recharge of regional and phreatic water tables. The presence of lime and mottles in the subsoils of valley bottom soils confirm flow in the phreatic zone.

Atterberg limits and indices, for example liquid limit (LL), plastic limit (PL), linear shrinkage (LS) and plasticity index (PI), are important soil properties in engineering and land evaluation for predicting soil mechanical behaviour. This study was conducted to develop and evaluate pedotransfer functions (PTFs) to predict Atterberg limits using measured and morphological soil properties from a large data set in South Africa covering a vast range of soils, geologies and climates. Five PTFs were developed; the first four using measured properties from 2330 soil horizons including extractable Fe, Al, Mn, Na, K, Mg and Ca; organic carbon (OC); pH (H2O); cation exchange capacity (CEC); and sand, silt and clay fractions to predict LL, PL, LS and PI. Morphological descriptors such as colour, structure (grade, size and type), consistency, occurrence of slickensides and cutans and abundance of roots were included in the second PTF using data from 717 horizons to predict PI. For all PTFs, two‐thirds of the data were randomly selected and used for model development and the remainder for validation. Prediction accuracies of R2 between 0.49 and 0.77 comparable to other studies on large data sets but underperformed when compared to localized data sets. For engineering purposes, site‐specific PTFs for prediction of Atterberg limits should be developed.