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An investigation into the health status of the wetlands delineating the lower Umngeni River floodplain, KwaZulu-Natal, South Africa.

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An amalgamation of a number of factors, inter alia, increased anthropogenic activity, reclaiming wetlands for other uses, poor planning of projected developments, and exponential population growth, have spurred a decline in the health status of wetland environments and interconnected river systems. This is particularly true of wetlands located within developed areas and is also characteristic of the floodplain wetlands of the Lower uMngeni River located in the eThekwini Municipality, KwaZulu-Natal, South Africa. The Lower uMngeni sub-catchment is heavily utilized and characterised by a multitude of human activities and land uses including urban and residential development, subsistence agriculture, recreational activity and, light and heavy industrial operations. Given this intensive development and the recognized value of wetlands, this study sought to determine the health status of the Lower uMngeni River and adjacent wetland systems by assessing contamination levels of the wetland soil, the wetland interstitial water and river water. Water and sediment samples were collected along transects established at strategically selected locations, each of which are situated at the intersection of different land uses or within close proximity of the major human activities within the locality. Such an approach allowed for inferences to be made regarding the potential anthropogenic sources of pollution. This was achieved by performing laboratory assessments, calculating geochemical indices and conducting statistical analyses for a range of physico-chemical parameters. The investigation also took into account the effect of seasonality on detected indicator concentrations in water samples, and determined compliance of measured concentrations with the prescribed DWAF limits. The findings indicate that wetland sediment displays signs of anthropogenic contamination, especially within the uppermost soil lamina, indicating the recency of pollution events. The dominance of fine-grained sediment in the wetlands indicated increased vulnerability to heavy metal and nutrient pollution. A strong positive relationship exists between wetland interstitial water and river water at most sample sites, indicative of the easy transfer of contaminants between these environments. Furthermore, elemental concentrations detected in interstitial water and/or river water varied according to seasonal rainfall patterns and were directly influenced by adjacent land uses. The majority of these concentrations were also non-compliant with the stipulated DWAF limits; necessitating that management, rehabilitation and monitoring measures be identified and implemented, where and if relevant, as a matter of urgency.


M. Sc. University of KwaZulu-Natal, Durban 2014.


Wetlands--KwaZulu-Natal., Wetland management--KwaZulu-Natal., Wetland restoration--KwaZulu-Natal., Watersheds--KwaZulu-Natal., Mgeni River Watershed (South Africa), Theses--Environmental science.