Viability analysis for investing in ecological infrastructure to secure water supply: A case study of South Africa

There is increasing understanding of the role that both ecological and built infrastructure can have in economic growth and development in terms of water supply. However, degradation of ecological infrastructure (EI) is resulting in the loss of valuable ecosystem services that benefit human well-being. Invasive alien plants (IAPs) are degrading catchment areas which negatively impacts delivery of hydrological ecosystem services. Clearing IAPs is considered a catchment conservation intervention that preserves these services. This study used South Africa as a case study to analyse the viability of investing in EI by way of IAP clearing compared to built infrastructure augmentation interventions to secure water supply in the long term. Unit reference values (URVs) were used to compare costeffectiveness between ecological and built interventions for 11 of South Africa's regional water supply systems (WSSs). Built infrastructure URVs were available from government reports, while URVs for EI were calculated by modelling spread of IAPs, calculating the cost to clear them between 2022 and 2050 and the potential amount of water saved in their absence. The results provide quantitative evidence of the cost-effectiveness of investing in EI against built infrastructure options to secure water supply. The potential water to be gained by clearing IAPs from catchment areas of existing bulk water infrastructure was approximately 40% of what would be gained by implementing all built infrastructure interventions by 2050. It is recommended that IAP clearing be pushed ahead of built infrastructure interventions to delay costs associated with further built infrastructure development. Governing institutions, economists and natural resource managers are therefore encouraged to coordinate efforts towards designing EI investment frameworks as a sustainable, resilient approach to securing water supply.

Grantor

Department of Biological Sciences

Year dc:date.issued

2023

Author dc:creator

• Webster, Kayla

Advisors dc:contributor.advisor

• Turpie, Jane
• Shackleton, Sheona
• Letley, Gwyneth

• Conservation Biology

Handle dc:identifier.uri

http://hdl.handle.net/11427/38202

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/38202