A study of the natural and anthropogenic impacts on the sediment and water quality of the middle and lower Mvoti River System, KwaZulu-Natal, South Africa.
Loading...
Date
2010
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
This dissertation focussed on the Mvoti River system in KwaZulu-Natal, an important
resource for the numerous towns and villages along its course. Catchment activities are
varied with agriculture being the predominant activity, and industrial activities common in the
lower catchment. The Mvoti River is intensively utilized, especially in its lower reaches, to the
extent that it is referred to as a ‘working river’. Modifications of the chemical and physical
characteristics of the system, and consequently the biological characteristics, have led to
degradation of the system such that the functioning of the lower river has deteriorated in
comparison to that of its pre-disturbance condition. There are three main aspects of the Mvoti
system around which this dissertation is based, namely, water quality, geochemistry, and
conservation of the system.
The results of the water quality survey of the estuary revealed that the system is presently
experiencing water which is of an inferior quality. Compared against the South African water
quality standards, a majority of the parameters exceed acceptable limits and are likely to
present negative impacts on aquatic health and potentially human health. Comparison of
current results, and water quality data for the system dating back to 1964, revealed that this
degradation is not new to the system, and the Mvoti Estuary has in fact been experiencing
continued deterioration over the years.
The second part of this study investigated heavy metal presence in the sediments of the
lower system and elemental presence and distribution in the surface sediments of the middle
and lower River respectively. Results indicated that even though selected heavy metals are
present, they are of concentrations lower than those of two other South African and two other
international systems they were compared with.
Enrichment and contamination assessments reveal that contaminants are in all probability
present as a result of anthropogenic sources. However, distribution patterns which show
highest levels just after effluent disposal sites suggest that the contamination is presumably
human-induced and, the predominance of larger grained sediments that do not have high
adsorption capacities, suggest that contaminants are readily remobilized into the water
column.
The final part of this research investigates other environmental problems, and causes, both
natural and anthropogenic, experienced by the estuary system. These stresses include poor
water quality, reduced water quantity, sedimentation, alien vegetation invasions and loss of
biodiversity. Strategies to address these issues are proposed, with the intention of improving
the condition of the estuary. This is an attempt at ecological restoration, to restore the
estuary to a condition as close to as possible, to its pre-disturbance condition. These
strategies include controlling abstraction and discharge, eradicating alien vegetation,
controlling sandmining, and improving the overall quality of the system. Also proposed is an
estuary management plan (EMP) for the Mvoti system, as there is currently no plan of such a
nature in place. The EMP will aid restoration attempts, increase public awareness, and via
post-project monitoring and evaluation ensure the success and sustainability of any future
projects. Significantly, the adoption of an EMP will be a major step towards the rehabilitation,
conservation and protection of this already degraded system.
Description
Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.
Keywords
Water quality--KwaZulu-Natal., Marine sediments--Quality., Environmental impact analysis., Theses--Environmental management.