A knowledge gap analysis on multi-scale predictive ability for agriculturally derived sediments under South African conditions

2007 ◽  
Vol 55 (3) ◽  
pp. 107-114 ◽  
Author(s):  
A.J. van Zyl
Keyword(s):  
South Africa ◽  
South African ◽  
Gap Analysis ◽  
Predictive Ability ◽  
Gully Erosion ◽  
Knowledge Gap ◽  
Catchment Scale ◽  
Erosion Processes ◽  
Modelling Framework ◽  
Erosion Modelling

Agriculture has been implicated as a major source of sediments in South Africa. The aim of the knowledge gap analysis was to understand the production and delivery components of agriculturally derived sediments under South African conditions and to assess the predictive ability to address the fate of these sediments from field to catchment scales. An overview is given of important erosion processes and erosion modelling applied in South Africa at the field and catchment scale. A limitation of the sediment models is that gully erosion is not simulated; therefore, the models should be complemented with gully erosion predictions if gullies are an important sediment source. Field-scale models inadequately predict sediment production localised at hydrologically sensitive areas as a result of saturation excess flow and/or throughflow. The discussion on erosion modelling reveals that more complex models have had limited application in South Africa because they require large and detailed data sets, and may have parameters that are difficult to measure or to estimate. A modelling framework is discussed which allows linking of sediment models requiring readily available data, gully erosion models/maps and the use of other techniques to assess the fate of agriculturally derived sediments from field to catchment scale.

Quantitative assessment of gully erosion dynamics using a GIS implementation of Sidorchuks' DYNGUL model in Southern KwaZulu-Natal, South Africa

2020 ◽  
Author(s):  
adel omran ◽  
Dietrich Schroeder ◽  
Christian Sommer ◽  
Volker Hochschild ◽  
Aleksey Sidorchuk ◽  
...  
Keyword(s):  
South Africa ◽  
Soil Erosion ◽  
Urban Areas ◽  
Side Wall ◽  
Mass Conservation ◽  
Gully Erosion ◽  
Physical Parameters ◽  
Erosion Model ◽  
Erosion Processes ◽  
Kwazulu Natal

<p>Soil erosion is considered as one of the main threats affecting both rural and urban areas in many different parts all over the world. Therefore, increasing attention has been attributed to soil erosion in the last decades. This can also be documented by an increasing number of studies targeting soil erosion assessment using qualitative and quantitative models. However, gully erosion phenomena have been widely neglected in erosion modelling due to the nature and complexity of the related processes and hence, it is also more difficult to simulate, predict and to visualize its effects. Sidorchuk (1999) established a Fortran based dynamic erosion model called DYNGUL to describe the first quick stage of gully development, coinciding with the main changes in gully morphology; like changes in volume, area and elevation of the longitudinal profile. The DYNGUL model is based on the solution of the equations of mass conservation and gully bed deformation. The model of straight slope stability was used to predict gully side wall inclination and of the finite morphology of the gully. The objective of this contribution is to establish a GIS tool for a quantitative gully erosion assessment and to predict gully evolution over time. The tool will help: i) to cope with or mitigate gully erosion processes and ii) to plan measures to stabilize the landscape affected by gully erosion. Therefore, we developed a Python-based tool that can be applied in a GIS environment. The model was tested its performance and the sensitivity of physical parameters with data from a gully in the Drakensberg Mountains, KwaZulu-Natal, South Africa. The results of the gully erosion model showed that their sensitivity to lithological and hydrological factors is rather high.</p>

Gully erosion: processes and models

1991 ◽  
Vol 15 (4) ◽  
pp. 392-406 ◽  
Author(s):  
Gerardo Bocco
Keyword(s):  
Gully Erosion ◽  
Future Research ◽  
Clear Understanding ◽  
Erosion Processes ◽  
Erosion Modelling

Confusing and sometimes contradictory results and reports have led to a sizeable body of literature on, but unfortunately not to a clear understanding of, gully erosion processes. In the following review, relevant concepts on gully erosion are summarized. Their implications for gully erosion modelling are presented along with some recommendations for future research.

scholarly journals Physically-based model for gully simulation: application to the Brazilian Semiarid Region

2019 ◽  
Author(s):  
Pedro Henrique Lima Alencar ◽  
José Carlos de Araújo ◽  
Adunias dos Santos Teixeira
Keyword(s):  
Gully Erosion ◽  
Semiarid Region ◽  
Physically Based Model ◽  
Erosion Processes ◽  
Cross Section Area ◽  
Section Area ◽  
Brazilian Semiarid ◽  
Physically Based ◽  
Erosion Modelling ◽  
Land Degradation And Desertification

Abstract. Gullies are one of the most relevant erosion processes, connected to land degradation and desertification, in special in arid and semiarid regions. Despite its role, gully erosion is neglected by many models and researches. This study presents a physically-based model for small permanent gullies, typical in the Brazilian Semiarid Region. The model consists of coupling two previous models, those by Foster and Lane (1983) and Sidorchuk (1999). As both models require input data of peak discharge and duration, different rain intensities were tested. The rain intensity that suited gully erosion modelling best was the 30-minute intensity. The Foster and Lane model supplied a better response for smaller areas, where bed-channel erosion is more pronounced. The Sidorchuk model presented a better performance in larger sections, where wall erosion becomes more prominent. The experimental area is located in the semiarid State of Ceará, Brazil, in which the land use is characterised by agriculture and livestock. We measured and modelled three gullies ageing almost six decades. The threshold between the prevailing domains of each process (channel bed or wall erosion) is based on the cross-section area; and it is intrinsically connected to wall erosion: for the case study, the threshold area was approximately 2 m2. The final model, hereby called FL-SM (Foster & Lane and Sidorchuk Model) performed very well, with Nash–Sutcliffe coefficient of 0.846.

scholarly journals Cointegration and stock market interdependence: Evidence from South Africa, India and the USA

2015 ◽  
Vol 18 (4) ◽  
pp. 475-485 ◽  
Author(s):  
Mohanasundaram Thangamuthu ◽  
Karthikeyan Parthasarathy
Keyword(s):  
South Africa ◽  
Stock Market ◽  
South African ◽  
Stock Markets ◽  
Predictive Ability ◽  
Series Data ◽  
The South ◽  
Long Run ◽  
The Usa ◽  
Short Run

The purpose of this study is to explore the nature of the association and the possible existence of a shortrun and long-run relationship between the stock-market indices of South Africa, India and the USA. The idea behind this combination is to know how the stock markets of these three prominent countries are related to each other. The study employs monthly data from the stock indices, namely JALSH (South Africa), NIFTY (India) and NASDAQ (USA) composite from April 2004 to March 2014. After testing for the normality of the data distribution and the stationarity of the time series data, this paper discovered a strong correlation between the stock market indices of South Africa, India and the USA. The correlation among the stock markets is high, particularly between South Africa and India. In addition, the paper attempts to discover the presence of any predictive ability among these markets by applying the Granger causality test. The result indicates that the NASDAQ index has no predictive ability as far as the JALSH and NIFTY indices are concerned. However, the JALSH index has a predictive ability on the NIFTY index. After testing the Granger cause relationship, the existence of a long-run and short-run relationship is tested. The long-run relationships among the stock market indices are analysed, following the Johansen and Juselius multivariate cointegration approach. The result suggests the absence of a long-run relationship among the three stock market indices. Short-run relationship is investigated with the Vector Autoregression (VAR) model, and the outcome obtained shows that both the USA and the South African stock markets are predicted only by their own past lags. However, the Indian stock market is seen to be a function of its own past lags and the past lags of the South African stock index. 

scholarly journals Illicit cigarette trade in South Africa: 2002–2017

2019 ◽  
Vol 29 (Suppl 4) ◽  
pp. s234-s242 ◽  
Author(s):  
Nicole Vellios ◽  
Corné van Walbeek ◽  
Hana Ross
Keyword(s):  
South Africa ◽  
South African ◽  
Gap Analysis ◽  
National Income ◽  
Effective Control ◽  
Control Mechanisms ◽  
Income Dynamics ◽  
Effective Measure ◽  
Illicit Trade ◽  
Nationally Representative

BackgroundIncreasing cigarette excise taxes is widely recognised as the most effective measure to reduce the demand for cigarettes. The presence of illicit trade undermines the effectiveness of tax increases as both a public health and a fiscal measure, because it introduces cheaper alternatives to legal, full-priced cigarettes.ObjectiveTo assess trends in the size of the illicit cigarette market in South Africa from 2002 to 2017 using gap analysis.MethodsTax-paid cigarette sales are compared with consumption estimates from two nationally representative surveys: the All Media and Products Survey and the National Income Dynamics Study. We explore the size of the illicit cigarette market and its changes over the period 2002–2017.ResultsSince 2009, illicit trade has increased sharply. We estimate that illicit trade is between 30% and 35% of the total market in 2017. The acceleration in the growth of the illicit market since 2015 corresponds with a turbulent time at the South African Revenue Service, when many of the enforcement functions were greatly reduced.ConclusionsThe current levels of illicit trade are extremely high and need to be addressed urgently by implementing effective control mechanisms such as a track and trace system to monitor the production, taxation, and sale of cigarettes.

scholarly journals The relationship between strategic process dimensions and organisational output performance: A South African investigation in relation to global best practices

2005 ◽  
Vol 36 (4) ◽  
pp. 69-79 ◽  
Author(s):  
H. Oosthuizen
Keyword(s):  
South Africa ◽  
Best Practices ◽  
Strategic Management ◽  
South African ◽  
Predictive Ability ◽  
Sub Saharan Africa ◽  
Average Output ◽  
Output Performance ◽  
Strategic Process ◽  
Innovative Behaviour

Strategic management is concerned with the foundations of sustainable superior output performance. In this regard two divergent, but complementary research traditions exist; one is rooted in micro-economics and is commonly referred to as the ‘hard’ aspects of strategy, whilst the other focuses on social-people aspects, commonly known as the ‘soft’ aspects of strategy. In emerging countries in Africa, Sub-Saharan Africa and South Africa the soft aspects have been emphasised in research with very little attention afforded to the hard process-behaviour of strategy.This paper contributes to an understanding and assessment of strategic process behaviour in South Africa. It firstly establishes a global best practices framework which provides for different contextual environments. This framework then serves as a benchmark for the empirical findings of a survey amongst South African manufacturing organisations.The research concludes that South African organisations achieving above-average output performance are those that closely reflect the profile of the global best practices framework. One core dimension of the strategic process, namely Implementation, was statistically found to be significantly related to above-average output performance. Aspects relating to innovative behaviour also displayed a statistical predictive ability towards above-average output performance.Finally, it is considered that the survey findings suggest an increasingly global context for South Africa and consequently the successful transfer (positive spillover) of strategic management knowledge from the developed to the developing world.Various research gap-areas were identified and need to be explored.

scholarly journals Usefulness of the English version of the Stress Overload Scale in a sample of employed South Africans

2021 ◽  
Vol 3 ◽  
Author(s):  
Charles H. Van Wijk
Keyword(s):  
Mental Health ◽  
South Africa ◽  
South African ◽  
Community Setting ◽  
Predictive Ability ◽  
Well Being ◽  
Local Health ◽  
English Version ◽  
South Africans ◽  
Validity Indices

Amidst reports of high levels of stress in South Africa, it remained difficult to quantify psychological stress in the absence of locally validated measures. This study explored the English version of the Stress Overload Scale (SOS) in a South African sample. The first aim was to replicate the basic psychometric analysis of the original English version used in American samples, as well as the Setswana version used in a South African rural community setting. The second aim was to investigate criterion validity to determine its appropriateness for use in South Africa. A total of 2136 employed South Africans with at least 9 years of schooling participated in this study. Participants completed a range of mental health and well-being measures, both clinical and dispositional. Responses were analysed to examine both scale characteristics and validity indices related to the SOS. Little sociodemographic influence (age, gender and first language) was found, with analyses supporting validity across most indices. Furthermore, good predictive ability for mental (ill-) health was observed. This study, for the most part, replicated previous validation findings of the SOS. Validity was further confirmed by correlating the scale with measures of clinical mental health and dispositional well-being. Given the positive support to its validity, when used amongst employed South Africans with at least 9 years of education, the scale holds promise for application in local health-related research, for triage in primary healthcare contexts and for measuring outcomes of mental health interventions in therapeutic settings.

Reframing Xenophobia in South Africa as Colour-Blind: The Limits of the Afro Phobia Thesis

2020 ◽  
Vol 17 (3) ◽  
pp. 433-444
Author(s):  
Amanuel Isak Tewolde
Keyword(s):  
South Africa ◽  
South African ◽  
Analytical Framework ◽  
Conflict Theory ◽  
Black African ◽  
South Africans ◽  
Theoretical Perspectives ◽  
Online Newspaper ◽  
Close Proximity ◽  
Realistic Conflict Theory

Many scholars and South African politicians characterize the widespread anti-foreigner sentiment and violence in South Africa as dislike against migrants and refugees of African origin which they named ‘Afro-phobia’. Drawing on online newspaper reports and academic sources, this paper rejects the Afro-phobia thesis and argues that other non-African migrants such as Asians (Pakistanis, Indians, Bangladeshis and Chinese) are also on the receiving end of xenophobia in post-apartheid South Africa. I contend that any ‘outsider’ (White, Asian or Black African) who lives and trades in South African townships and informal settlements is scapegoated and attacked. I term this phenomenon ‘colour-blind xenophobia’. By proposing this analytical framework and integrating two theoretical perspectives — proximity-based ‘Realistic Conflict Theory (RCT)’ and Neocosmos’ exclusivist citizenship model — I contend that xenophobia in South Africa targets those who are in close proximity to disadvantaged Black South Africans and who are deemed outsiders (e.g., Asian, African even White residents and traders) and reject arguments that describe xenophobia in South Africa as targeting Black African refugees and migrants.

Region of Birth and Child Mortality among Black Migrants to South Africa: Is there a foreign-born advantage?

2016 ◽  
Vol 13 (3) ◽  
pp. 359-376 ◽  
Author(s):  
Tiffany L Green ◽  
Amos C Peters
Keyword(s):  
South Africa ◽  
South African ◽  
Child Mortality ◽  
Southern Africa ◽  
Strong Relationship ◽  
Developed Countries ◽  
Black Immigrants ◽  
Foreign Born ◽  
Region Of Origin ◽  
Child Deaths

Much of the existing evidence for the healthy immigrant advantage comes from developed countries. We investigate whether an immigrant health advantage exists in South Africa, an important emerging economy.  Using the 2001 South African Census, this study examines differences in child mortality between native-born South African and immigrant blacks.  We find that accounting for region of origin is critical: immigrants from southern Africa are more likely to experience higher lifetime child mortality compared to the native-born population.  Further, immigrants from outside of southern Africa are less likely than both groups to experience child deaths.  Finally, in contrast to patterns observed in developed countries, we detect a strong relationship between schooling and child mortality among black immigrants.

Some Reflections on Reparation in Post-Apartheid South Africa, using a Couple Therapy Intervention as a Microcosm of South African Society

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Andrea Hill ◽  
Sylvia Poss
Keyword(s):  
South Africa ◽  
South African ◽  
Couple Therapy ◽  
South African Society ◽  
Depressive Position ◽  
Central Hypothesis ◽  
Transference And Countertransference ◽  
Constructive Engagement ◽  
The Impact ◽  
Therapy Intervention

The paper addresses the question of reparation in post-apartheid South Africa. The central hypothesis of the paper is that in South Africa current traumas or losses, such as the 2008 xenophobic attacks, may activate a ‘shared unconscious phantasy’ of irreparable damage inflicted by apartheid on the collective psyche of the South African nation which could block constructive engagement and healing. A brief couple therapy intervention by a white therapist with a black couple is used as a ‘microcosm’ to explore this question. The impact of an extreme current loss, when earlier losses have been sustained, is explored. Additionally, the impact of racial difference on the transference and countertransference between the therapist and the couple is explored to illustrate factors complicating the productive grieving and working through of the depressive position towards reparation.

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