Time filter

Source Type

Johannesburg, South Africa

Malherbe W.,North West University South Africa | Mahlangu S.,University of Johannesburg | Ferreira M.,University of Johannesburg | Ferreira M.,Jeffares and Green Pty Ltd | Wepener V.,North West University South Africa
African Journal of Aquatic Science | Year: 2015

The Harts River and its associated floodplain, Northern Cape province, South Africa, are closely associated with the Vaalharts Irrigation Scheme. This floodplain has been poorly studied in the past, with no published aquatic information available. A fish and macroinvertebrate diversity study was undertaken in April 2009 to compare the faunal diversity of the floodplain to that of the Harts River. Numerous taxa found on the floodplain were not present at the river sites. The smaller fish species that prefer lotic habitats were especially abundant in the floodplain compared to the Harts River. Overall, biodiversity of the region in terms of macroinvertebrates increased if the floodplain was taken into account, and therefore the protection of the floodplain through flow regulation and monitoring is essential. © 2015 NISC (Pty) Ltd.

Foster L.,University of Johannesburg | Malherbe W.,North West University South Africa | Ferreira M.,University of Johannesburg | Ferreira M.,Jeffares and Green Pty Ltd | van Vuren J.H.J.,University of Johannesburg
African Journal of Aquatic Science | Year: 2015

Aquatic macroinvertebrates are rarely used in wetland assessments due to their variation. However, in terms of biodiversity, these invertebrates form an important component of wetland fauna. Spatial and temporal variation of macroinvertebrate assemblages in endorheic depressions (locally referred to as pans) in Mpumalanga and North West provinces were compared in wet and dry seasons in 2012 and 2013. A total of 29 taxa were identified from both provinces, with similarities in the structure of communities, with the exception of one or two species, in perennial endorheic depressions in both provinces. Macroinvertebrates sampled in Mpumalanga endorheic depressions were similar to those reported in previous studies completed in the area, and most macroinvertebrates sampled in Mpumalanga and North West were known to be commonly found in temporary habitats. Long-term studies are required to understand better the ecological functioning of the pans in the North West province. © 2015 NISC (Pty) Ltd.

Henri A.J.,University of Johannesburg | Wepener V.,North West University South Africa | Ferreira M.,University of Johannesburg | Ferreira M.,Jeffares and Green Pty Ltd | And 3 more authors.
Hydrobiologia | Year: 2014

Endorheic wetlands are abundant in South Africa, and are more commonly referred to as pans. The pan environment experiences daily and seasonal fluctuations in physico-chemical conditions, caused by variable hydroperiods. Branchiopod crustaceans are a unique group of fauna which are able to survive this variability through the production of dormant egg banks. The endorheic nature of these wetlands makes them more vulnerable to anthropogenic activities. A decrease in the hatching success of branchiopods could be detrimental to the biodiversity and ecosystem functioning of these wetlands. Pans were selected from regions where increasing mining activities are a potential risk. The sediment collected from selected pans was inundated with two saline solutions of 1,000 and 1,500 mg/l, respectively, which served as controls. A third solution of decanted acid mine drainage (AMD) was used to determine hatching success with exposure to AMD. Findings showed that AMD had a negative effect on the hatching success from egg banks. Recovery experiments were performed to assess whether egg banks could recover from AMD exposure upon first inundation. Recovery rates were low and support the concern that affected wetlands will suffer a loss of biodiversity. © 2014 Springer International Publishing Switzerland.

Smithers J.C.,University of KwaZulu - Natal | Smithers J.C.,Jeffares and Green Pty Ltd | Streatfield J.,Jeffares and Green Pty Ltd | Gray R.P.,Jeffares and Green Pty Ltd | Oakes E.G.M.,Jeffares and Green Pty Ltd
Water SA | Year: 2015

Estimates of design floods are required for the design of hydraulic structures and to quantify the risk of failure of the structures. Many international studies have shown that design floods estimated using a regionalised method result in more reliable estimates of design floods than values computed from a single site or from other methods. A number of regional flood frequency analysis (RFFA) methods have been developed, which cover all or parts of South Africa. These include methods developed by Van Bladeren (1993), Mkhandi et al. (2000), Görgens (2007) and Haile (2011). The performance of these methods has been assessed at selected flow-gauging sites in the province of KwaZulu-Natal (KZN), South Africa. It is recommended that the limitations of available flow records to estimate extreme flow events need to be urgently addressed. From the results for KZN the JPV method, with a regionalised GEV distribution with the veld zone regionalisation, generally gave the best performance when compared to design floods estimated from the annual maximum series extracted from the observed data. It is recommended that the performance of the various RFFA methods needs to be assessed at a national scale and that a more detailed regionalisation be used in the development of an updated RFFA method for South Africa. © 2015, South African Water Research Commission. All rights reserved.

Discover hidden collaborations