Abstract
Tshwane Metropolitan Municipality. The river forms a confluence with the Olifantspruit towards the north which flows further northward and into the Hennops River. The Kaalspruit has been plagued with water quality issues over the previous years with various concerns about the health risks posed by the level of pollution in the river to the surrounding communities. The aim of the study was to investigate the ecological status of the river through physico-chemical assessment of water and sediment in the river; biological and habitat assessment of macroinvertebrates; and finally, the development of recommendations for a management plan for rehabilitation. Field surveys were undertaken during the wet season (September 2018) and dry season (June 2019). In-situ water quality parameters were measured during field visits. Laboratory analyses were performed on nutrients, total phosphates, chlorophyll-a and faecal coliforms. The presence of metals and chemical compounds (OCPs, SVOCs, PCBs and Phenols) was also determined in both water and sediment through lab analyses. Macroinvertebrate assessment and habitat assessment was conducted through South African Scoring System version 5 (SASS) and Integrated Habitat Assessment System (IHAS) to determine the abundance and diversity of macroinvertebrate communities and the availability of habitat. The water quality results revealed generally poor conditions with minimal seasonal variations; showing low dissolved oxygen, and high faecal coliforms and nutrient concentrations. Metal concentrations showed variations with some metals present in intolerable amounts. Chemical compounds also showed higher concentrations for sediment, with OCPs such as DDT showing higher concentrations at sites close to agriculture fields. Finally, macroinvertebrate results showed poor diversity and abundance of macroinvertebrate taxa with low SASS scores and ASPT values; with all taxa identified being pollution tolerant. Habitat assessment results also generally showed poor availability in habitat quality and mostly supporting the poor diversity and abundance of macroinvertebrate communities. The general interpretation of the results is that the system is negatively impacted, and the ecological integrity is degraded. These results indicate that a strong management plan ought to be developed with stringent rehabilitative measures. As such, recommendations for a management plan which includes multi-departmental collaboration and community engagement, including water quality improvement measures are also provided in this study.
M.Sc. (Environmental Management)