The contribution of Integrated Development Projects to Zandspruit River water pollution, Gauteng Province, South Africa

Abstract

Cosmo City Integrated Development Project is a mixed-use, integrated housing and inclusionary housing development for families from different income groups. The project was conceived in response to the needs of the people located close to Zandspruit River system. This research was conducted in Cosmo City to understand the contribution of the integrated development activities to pollution of Zandspruit River system upstream and downstream. The study characterized and measured the major pollutant sources found in Zandspruit River system water, analysed the potential impact of pollutants associated with the Cosmo City development and recommended strategies to minimize the pollution levels. Water and sediments samples were collected from Zandspruit River system across five study sites. The kick sampling method was used for the sediment and rocks while a handheld sweeping net was used for zig-zag approach. Macroinvertebrate samples were collected in ziplock bags and stored in polypropylene 500 mL plastic bottles. The results showed a total number of six macroinvertebrates taxa out of possible fourteen during the study periods. These included Dytiscidae, Gerridae, Hydrometridae, Aeshnidae, Chlorolestidae and Lymnaeidae. The results also showed that the volume of macroinvertebrate taxa such as Gerridae, Chlorolestidae and Lymnaeidae were high across the Zandspruit River system, implying that the river system was polluted by human made activities. Research further indicated that the volume of macroinvertebrate taxa such as Dytiscidae, Hydrometridae and Aeshnidae were lower across the river system, indicating the low level of pollution and the possible cause of this variation was from water pollution. Water pH values for April and June ranged between 5.8 to 8, respectively, across all the sites as indicated by pH, alkalinity, temperature and conductivity across Zandspruit River system perhaps due to less human made activities. The study findings indicated that sediment chemical like S, Ca, EC, Mg were high while OC, B, Cu, Zn, Fe, Mn were relatively lower during April as well as June. Water chemical properties like Na, alkalinity, Ca, Mg and Cl were relatively higher for both months, whereas variables such as Mn, Fe, S and K were relatively lower across streams during the same period. The possible conclusion was that different activities such as residential, fishing, farming and industrial along the Zandspruit River system have significant pollution implication. The study further concluded that residential activities have high potential pollution contribution to Zandspruit River system. The major recommendation for minimising water pollution can be sustainable strategies to minimize the level of water pollution in development activities on adjacent rivers.