Standardisation of Hydropedology Assessments in South Africa

Posted on 8 Feb 2021

Hydropedology is the study of the hydrological interactions of water with soil and the fractured rock zone (WRC, 2019) and makes it possible to identify water resources and flowpaths in a hillslope. By studying the physical characteristics of the different soil forms, such as porosity and conductivity, as well as the morphological properties of the soil one can determine the dominant hydrological processes within the profile and in turn the hillslope. These hydrological processes, such as storage mechanisms, water flow paths and the connectivity between different flow paths, can then be characterised and conceptualised. The ability of the practitioner to spatially conceptualise these hydrological processes is a great benefit of the science of hydropedology, as this allows for more informed planning and management of water resources within the applicable catchment areas. Hydropedology is not a new science, but has in recent times become of national importance as a mechanisms to better quantify the influence of development on the water resources of South Africa. To date, there has not been a standardised approach to conducting hydropedological studies for various authorisation processes in South Africa. However, as of the 26th January 2021 the Guidelines for Hydrological Assessments and Minimum Requirements (Van tol et al., 2021) were released by the national Department of Water and Sanitation (DWS) and its scientific partners.

 

The Guidelines for Hydropedological Assessments and Minimum Requirements (Van Tol et al., 2021) are divided into four (4) steps, as presented below, that are relevant to specific levels of assessment. Steps 1 and 2 are required for any impact assessment for which a hydropedological study is communicated to be a requirement by the Competent Authority (CA), whereas Steps 3 and 4 will typically be required for projects where large scale changes to land cover may occur (e.g. large infrastructural developments and open-pit mining). The addition of Steps 3 and 4 should be clarified with the CA during the preapplication process.  

 

  • Step 1: Identification of the Representative Hillslope/s
  • Step 2: Conceptualise the Hillslope Hydropedological Responses via inter alia:
    • Transect surveys;
    • Soil description and classification; and finally
    • Conceptualise the hillslope hydropedological response.
  • Step 3: Quantification of Hydraulic Properties and Flowrates
  • Step 4: Quantification of Hydropedological Fluxes

 

By classifying the hillslope, and thus the dominant hydrological processes within it, proposed development and/or conservation efforts on it or within the catchment area can be planned according to the potential impact/benefit it may have on the wetland/stream typically situated at the valley bottom.

 

The highly qualified specialist team at Environmental Assurance (ENVASS) recognize the importance and value of this exciting new field and its application. We have thus been involved in consultation with the DWS and various ‘founding fathers’ to refine our ability to undertake hydropedology studies for various sectors of the economy at a very high level. If ever the need arises, please do not hesitate to contact ENVASS for hydropedology studies, including: buffer zone determination, wetland/stream flow requirements, impact assessments, hillslope classification, land use planning and pollution migration assessments. You can contact us on 012 460 9768, or email us on info@envass.co.za. We look forward to hearing from you!