Academy of Science of South Africa (ASSAf): Open Journal Systems
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Utilization of hydrodynamic modelling to quantify water losses from the Sundays River between Darlington Dam and Korhaans Drift Weir
No full textThis study quantified transfer losses over the 2021/2022 water year for irrigation releases from Darlington Dam into the Sundays River, which are diverted at the Korhaans Drift Weir. A one-dimensional (1D) hydrodynamic model was set up and calibrated to simulate the transfer losses which were assumed to consist primarily of evaporation and evapotranspiration (ET). Flow measurements were undertaken with an acoustic doppler current profiler (ADCP) to verify the calibrations of the Parshall flumes at Darlington Dam and at Korhaans Drift Weir. The ADCP results showed that the Department of Water and Sanitation’s (DWS’s) existing discharge tables underestimated lower flows by 13% and higher flows by 16%. The hydrodynamic model results also estimated transfer losses between Darlington Dam and Korhaans Drift to range between 2.0% and 5.3%. It was determined that the transfer losses were seasonal and were lower than those determined by similar studies for other South African rivers
THE PLIGHT OF SOUTH AFRICAN WHISTLE-BLOWERS: SEARCHING FOR EFFECTIVE PROTECTION
No full textDaily reports in the media about the extent of corruption in South Africa and the plight of whistle-blowers who dare to report it demonstrates the inadequacy of protective measures in South Africa. The murder of whistle-blower Babita Deokaran saw other whistle-blowers go into hiding, fearing for their own safety, and calls for urgent measures to be implemented to ensure the physical safety of whistle-blowers. The United Nations Convention Against Corruption (UNCAC) contains measures that could be implemented to protect the physical safety of whistle-blowers. Currently, the only legislation specifically protecting whistle-blowers in South Africa is the Protected Disclosures Act (PDA), which only protects against detriment in the workplace. A number of other statutes provide a measure of protection, but they are fragmented and by no means adequate. A legal comparison with the United Kingdom (UK), Ireland and the United States of America (US) may provide guidelines for reform in South Africa. The UK is currently debating the Protection for Whistleblowing Bill (Bill 27) in the House of Lords to improve protection for whistle-blowers. This Bill proposes to sever the required link to employment so that any person reporting wrongdoing will be protected if certain requirements are met. Bill 27 also establishes the Office of the Whistleblower, which has wide-ranging powers to protect whistle-blowers. The Irish Protected Disclosures (Amendment) Act 2022 was amended to broaden the definition of “worker” to include persons not previously protected and to establish an Office of the Commissioner similar to the Office of the Whistleblower in Bill 27, although with limited power. Neither the UK nor Ireland requires whistle-blowers to report in good faith; the focus is on the message instead of the messenger. Financial rewards for whistle-blowers in the US have proved to be highly successful and could be implemented in South Africa. It is recommended that physical protection of whistleblowers be prioritised, that a Whistle-Blowers’ Office with wide-ranging powers be established, that protection be extended to persons outside the employment relationship, that whistle-blowers be rewarded for reporting on wrongdoing in prescribed circumstances, that the burden of proof be reversed and that the good faith requirement for protection be dropped
Including Children's Views in Divorce Mediation: A Comparative Analysis and Recommendations or Kenya
No full textIt is important that the views of children be considered during the process of their parents' divorce. Parental divorce mediation informed by the needs of children is more likely to produce better outcomes. The ways in which divorce mediators in South Africa, Australia and Kenya consider views of the children of marriages in the process of dissolution are compared. The extent to which these three countries have domesticated and implemented relevant international law and policies is compared. Recommendations are provided for Kenya, where empirical research was undertaken to establish the practices and attitudes of Kenyan divorce mediators. The outcome of this empirical research indicates that – prior to mediating between their parents – most of Kenya's divorce mediators fail to elicit the views and wishes of the children who will be affected by the divorce. Proposals are put forward on how this may be rectified. In formulating these proposals, practices in South Africa and Australia are examined for the purposes of comparative analysis. The recommendations for Kenya include the formulation of appropriate laws and policies; the establishment of cost-effective mechanisms for hearing the voices of children prior to their parents' divorce mediation; and the education of the general public on the importance of considering the views and wishes of children when their parents are divorcing
Alternative streamflow-based approach to estimate catchment response time in medium to large catchments: case study in Primary Drainage Region X, South Africa
No full textEvent-based estimates of the design flood in ungauged catchments are normally based on a single catchment response time parameter expressed as either the time of concentration (TC), lag time (TL) and/or time to peak (TP). In small, gauged catchments, a simplified convolution process between a single observed hyetograph and hydrograph is generally used to estimate these time parameters. In medium to large heterogeneous, gauged catchments, such a simplification is neither practical nor applicable, given that the variable antecedent soil moisture status resulting from previous rainfall events and spatially non-uniform rainfall hyetographs can result in multi-peaked hydrographs. In ungauged catchments, time parameters are estimated using either empirical or hydraulic methods. In South Africa (SA), unfortunately, the majority of the empirical methods recommended for general use were developed and verified in catchments ≤ 0.45 km² without using any local data. This paper presents the further development and verification of the streamflow-based approach developed by Gericke (2016) to estimate observed TP values and to derive a regional empirical TP equation in Primary Drainage Region X, SA. A semi-automated hydrograph analysis tool was developed to extract and analyse complete hydrographs for time parameter estimation using primary streamflow data from 51 flow-gauging sites. The observed TP values were estimated using three methods: (i) duration of total net rise of a multi-peaked hydrograph, (ii) triangular-shaped direct runoff hydrograph approximations, and (iii) linear catchment response functions. The combined use of these methods incorporated the high variability of event-based time parameters, and Method (iii), in conjunction with an ensemble-event approach sampled from the time parameter distributions, should replace the event-based approaches to enable the improved calibration of empirical time parameter equations. The conceptual approach used to derive the regional empirical TP equation should also be adopted when regional equations need to be derived at a national scale in SA
Water use and potential hydrological implications of fast-growing Eucalyptus grandis x Eucalyptus urophylla hybrid in northern Zululand, South Africa
No full textWe measured the tree transpiration of 9-year-old, Eucalyptus grandis x Eucalyptus urophylla clonal hybrid (GU) trees in the commercial forestry area of northern KwaZulu-Natal, South Africa. Transpiration was measured using the heat ratio method over two consecutive hydrological years (2019/20 and 2020/21) and up-scaled to a stand level. Leaf area index (LAI), quadratic mean diameter, and soil water content (SWC) were measured over the same period using an LAI 2200 plant canopy analyser, manual dendrometers and CS616 sensors, respectively. The depth to groundwater was estimated to be approx. 28 m, using a borehole next to our study site. Results showed that transpiration followed a seasonal pattern, with daily mean of 2.3 mm‧tree−1‧day−1 (range: 0.18 to 4.55 mm‧tree−1‧day−1) and 3.3 mm‧tree−1‧day−1 (range: 0.06 to 6.6 mm‧tree−1‧day−1) for 2019/20 and 2020/21, respectively. Annual GU transpiration was higher than that found by international studies under similar conditions, but was within the same transpiration range as Eucalyptus genotypes in the KwaMbonambi area. Plantation water productivity, calculated as a ratio of stand volume to transpiration, was higher than for other published studies, which was attributed to a very high productive potential of the study site. Multiple regression using the random forests predictive model indicated that solar radiation, SWC and air temperature highly influence transpiration. There is a high possibility that our GU tree rooting system extracted water in the unsaturated zone during the dry season. Due to the use of short-term results in this study, the impact of GU on water resources could not be quantified; however, previous long-term paired catchment studies in South Africa concluded that Eucalyptus has a negative impact on water resources. Further research is suggested with long-term measurements of transpiration and total evaporation and an isotope study to confirm the use of water by GU trees in the unsaturated zone
Non-Educator Stakeholders and Public-School Principals' Views on the Proposed Amendments to the South African Schools Act 84 of 1996
No full textOn 13 October 2017, the Department of Basic Education (DBE) published Government Gazette No 41178 pertaining to the Basic Education Laws Amendment Bill (hereinafter BELA). The draft bill proposes to amend certain sections of the South African Schools Act 84 of 1996. The DBE gave education stakeholders a window period to make inputs on the proposed Bill. Over 5000 submissions were received.
On 27 and 28 January 2020, Ms Angie Motshekga (Minister of Basic Education) invited the educator unions and governing body federations to further consultations on the Bill. The Bill was again circulated to the public in 2021 in Government Gazette number 45601 after further amendments.
In this article, the authors discuss school principals’ (as education stakeholders) opinions on the proposed amendments with a specific focus on school admission and language policies.
The research on which this article is based was located within the framework of government and management terms like the decentralisation and recentralisation of the powers of principals and school governing bodies (SGBs) and the recent phenomenon of political realism.
The research took the form of a qualitative case study using triangulation (semi-structured interviews, literature review and document analysis) to gather data.
The data produced mixed results. Some education stakeholders were very critical of the proposed amendments to the South African Schools Act while other groups welcomed the proposed changes. Some principals felt that the government was employing political realism in rescinding (recentralising) some of the powers that had been devolved to them in 1996 after the dawn of democracy in South Africa. They believed that the recentralisation would impede their autonomy when they carry out their professional and governance duties (the duties the school governing body delegated to the principal) in partnership with their SGBs. They believed it represented a regression to apartheid education. Other principals welcomed a more centralised governance approach where school leadership was dysfunctional and where SGBs provided no meaningful assistance to school principals
On the Flow Characteristics (FC) method for estimating sustainable borehole yield
No full textFlow Characteristics (FC) is one of the few methods developed for predicting long-term sustainable borehole yield of single wells in typical fractured rock aquifers. The FC method uses drawdown derivatives and subjective information on no-flow boundaries to estimate a sustainable borehole yield that should not cause the water level to drop below the main water strike (fracture) during long-term operations. Since its development, the FC method has been widely applied in many research and consulting projects. Two decades after its development, a review of its technical capabilities and limitations is necessary to enhance understanding among groundwater practitioners while building a platform for further improvements. The main strength of the method is its simplicity of use, its ability to protect the main water strike/fracture, and its lower susceptibility to the influence of aquifer heterogeneities because it does not require the input of aquifer storativity and transmissivity. The FC method also caters to the negative influence of impermeable boundaries, thereby enabling planning for different low-yield-causing scenarios. However, the major limitation is in using the subjective closed no-flow boundary without factoring aquifer storativity and the distance of the closed no-flow boundary from the pumping well. Under the influence of the closed no-flow boundary, the water must come from aquifer storage, hence the storativity and the size of the bounded aquifer are very critical parameters. It is therefore incorrect to factor in the influence of the closed no-flow boundary without considering its exact location. This limitation is reflected in the absence of criteria to determine the distance of the closed no-flow boundary from the pumping well for validating the FC results using numerical models. The FC method still needs validation using field operational data; other recommendations for future research are highlighted in the discussion
The effect of permanent protective netting on insect pest prevalence in citrus orchards in South Africa
No full textThe use of protective netting is becoming an increasingly popular practice in the citrus industry in South Africa. However, data on its effects on biotic factors, particularly insect pests, are limited. This study focused on the effect nets have on key citrus pests in the Eastern Cape province. Orchards under nets and open orchards, of similar cultivars, ages and management practices, were monitored at several sites over two seasons for pest infestation and damage. Weekly monitoring was conducted for Thaumatotibia leucotreta infestation. Other pests were monitored either monthly or once a season. During the first season, T. leucotreta infestation was higher in orchards under nets, probably because, unlike the open orchards, the nets provided protection for the existing high levels of T. leucotreta. No T. leucotreta infestation was recorded in both orchard types in 2019. This was due to generally lower than usual pest abundance and dramatically improved area-wide management of T. leucotreta. Pheromone traps were used to monitor T. leucotreta males, including sterile moths used in a sterile insect technique programme. Although higher catches of wild T. leucotreta moths were recorded in orchards under nets, so too were there higher numbers of sterile moths and a higher ratio of sterile to wild moths, indicating the potential for better pest suppression for orchards under nets. Various other key pests were monitored during this time, with variable results for each species. Pests that were elevated under nets include Planococcus citri and Aonidiella aurantii. Pests that seemed to be lower under nets were Ceratitis capitata and Scirtothrips aurantii. Nets had no effect on Empoasca distinguenda, Penthimiola bella and Eriophyes sheldoni. These differences in pest levels in netted and open orchards trigger an important debate on whether nets are beneficial for or detrimental to the successful implementation of an integrated pest management programme