UNAM Open Access Journal University of Namibia
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A distributed water balance model to estimate direct groundwater recharge: A case study from the nhoma and khaudum catchments, Namibia
Get PDFThe most important water resource in drylands such as Namibia is groundwater and itsrecharge including temporal and spatial variations need to be assessed reliably for sustainable water management. In this paper, a grid-based conceptual water balance model witha simplification at the catchment scale level is used to assess groundwater recharge. Thereliability of the model predictions are verified by the independent chloride mass balancemethod. The distributed, process-oriented, physically based water balance model MOD-BIL used in this study considers the major water balance components and calculates aspatially differentiated water balance by simulating water fluxes and storages at temporaland spatial resolutions based on meteorological, topographic, soil physical, land coverand geological input parameters. In this study it is set up for the upper Khaudum andNhoma catchments in the Kalahari of north-eastern Namibia and northwestern Botswanaat a spatial resolution of 500 x 500 m, calculated daily for a period of 22 years. A meanannual area groundwater recharge of 11.5 mm a⁻¹ is calculated for the catchments, butspatial variations between 0 and 17.5 mm a⁻¹occur depending on the variability of vegetation, soil and geomorphology. Groundwater recharge only occurred on a few daysduring the simulation period
Phytochemical analysis and in vitro anti-plasmodial activity of selected ethnomedicinal plants used to treat malaria associated symptoms in northern Namibia
Get PDFThe search for biologically active compounds from plants is of importance for discovery of novel medicine against infectious diseases such as malaria. The aims of this study were to identify ethno-medicinal plants that are used to treat malaria-associated symptoms in traditional settings in northern Namibia; to detect and quantify the presence of major anti-plasmodial phytochemicals to evaluate the anti-plasmodial activity against Plasmodium falciparum 3D7A strain of the extracts of lead plants. Ten plants were identified through a survey conducted by the Multidisciplinary Research Centre at the University of Namibia. Nineteen methanolic extracts from 10 selected ethnomedicinal plants were prepared and analyzed using Thin Layer Chromatography (TLC) to detect classes of anti-plasmodial phytochemical compounds. Furthermore, total phenolic and alkaloids were also quantified. Furthermore, in vitro anti-plasmodial activity of crude methanol and aqueous extracts at 5, 10 and 50 mg/ml was evaluated against P. falciparum 3D7A strain at 1% parasitaemia and 2% hematocrit after 48 hours. The study revealed the presence of at least one of the major anti-plasmodial classes of compounds such as terpenoids, alkaloids, anthraquinones, flavonoids and coumarins in all the plant extracts analyzed. Out of 10 plant species, Mundulea sericea’s shoots indicated the presence of all five major anti-plasmodial phytochemical. The plants species studied show a high estimate of total alkaloids (0.37- 21.21 mg/1g of extracts) and phenolics (99. 58 - 444.07 GA/E mg/ml). Methanol extracts of M. sericea, D. mespiliformis and Cyphostemma spp showed the best anti-plasmodial activity with range of IC50 values from 3.179 to 3.523 mg/ml. The presence of anti-plasmodial phytochemical classes of compounds and high in vitro anti-plasmodial activity of selected plants extracts support the further investigation of these plants, as potential sources of novel anti-plasmodial compounds for malaria drug discovery
A distributed water balance model to estimate direct groundwater recharge: A case study from the nhoma and khaudum catchments, Namibia
Get PDFThe most important water resource in drylands such as Namibia is groundwater and itsrecharge including temporal and spatial variations need to be assessed reliably for sustainable water management. In this paper, a grid-based conceptual water balance model witha simplification at the catchment scale level is used to assess groundwater recharge. Thereliability of the model predictions are verified by the independent chloride mass balancemethod. The distributed, process-oriented, physically based water balance model MOD-BIL used in this study considers the major water balance components and calculates aspatially differentiated water balance by simulating water fluxes and storages at temporaland spatial resolutions based on meteorological, topographic, soil physical, land coverand geological input parameters. In this study it is set up for the upper Khaudum andNhoma catchments in the Kalahari of north-eastern Namibia and northwestern Botswanaat a spatial resolution of 500 x 500 m, calculated daily for a period of 22 years. A meanannual area groundwater recharge of 11.5 mm a⁻¹ is calculated for the catchments, butspatial variations between 0 and 17.5 mm a⁻¹occur depending on the variability of vegetation, soil and geomorphology. Groundwater recharge only occurred on a few daysduring the simulation period
On the smoothness and the totally strong properties for nearness frames
Get PDFIn this paper we briefly explore the properties of smooth and totally strong nearness frames. It turns out that there is a relationship between them, in particular, totally strong nearness frames are smooth. We also show that the category of smooth nearness frames is coproductive, and that, as is the case with that of the totally strong ones, it is closed under completions
Educational Emulation of a Soft Handoff Teaching Model (EESH-TM)
Get PDFThe use of fixed Base and Mobile Stations offer a set of challenges dealing with the movement of a Mobile Station away from one Base Station toward a second Base Station. In this situation, the signal strength decreases as the distance of the mobile position increases (following an inverse-square law) from the first station; while an increase in signal strength is experienced as the distance decreases from the second one. Gradually the signal from the former is lost. This is a difficult problem in wireless technology, not only to picture but also to solve. This problem which is prominent in mobile and wireless applications is called ”Soft Handoff”, the solution of which applies the concept of ”make-before-break”, which postulates the smooth and gradual transition of signals from the previous Base Station to the next one without causing a sharp break or interruption of the signal. Such a hypothetically smooth and soft hand over signal mechanism is very difficult for students to understand especially those who have had little or no experience with telecommunication equipment, with the analysis of wireless circuits or with hands-on experience with the technology. This became evident when the topic was initially covered in a Telecommunications course at University of Namibia. It was within this context that the Educational Emulation of Soft Handoff Teaching Model (EESH-TM) was designed and developed to model the mechanism of Soft Handoff. The EESH-TM is comprised of: two Base Stations, two Cells, a Mobile Station, and two interacting signals. This teaching model clearly demonstrated, step-by-step, various scenarios with a mobile unit moving between two Base Stations clearly illustrating how Soft Handoff works. Hence, the utilization of this teaching tool presented inexperienced students with an opportunity to observe and understand how signal hand off works in a wireless network. The success of the model was demonstrated by higher examination scores and greater student interest in the topic
Seasonal changes in avian assemblages in kaokoland (mopane) savanna in the ogongo game reserve, north-central Namibia
Get PDFStudies were conducted at UNAM Game Reserve (c. 1000 ha) in the BIOTA Observatory ’Ogongo’, which is located c. 50 km NW of Oshakati, north-central Namibia (17 700S, 15 310E). The natural vegetation of this area is the Koakoland (Mopane) Savanna. In 2011-2012, the line transect method has been employed to assess the species composition, dominance structure, and relative abundance of all bird species, and their seasonal changes in the late rainy season (March), middle of dry season (July), and beginning of rainy season (November). In total, 66 resident (46 in late rainy season, only 35 in the middle of dry season and 39 at the beginning of rainy season) and 19 non-resident species were recorded. Only two resident species have been classified as dominants in all three seasons: Plocepasser mahali and Uraeginthus angolensis; five species were dominants in two, and four species in one season. The avian assemblage undergoes significant seasonal changes, mostly related to the water regime in oshanas. Although the number and proportion of dominant species changed only slightly from season to season (6-7 species; 58.8-62.4% of contribution), highly significant seasonal differences in abundance were recorded for 18 resident species. Clear seasonal changes were also found in the proportions of main feeding guilds, i.e. granivores and insectivores. In comparison with other habitats in Namibia, Ogongo Game Reserve has a rich and diverse avifauna. For many bird species the reserve constitutes a safe breeding habitat, and a rich feeding area. It is fully justified to retain its status as nature sanctuary in Cuvelai Drainage ecosystem
Community perceptions of climate change and vanability impacts in Oshana and Ohangwena Regions
No full textThe links between climate change, social and economic development, health, and environmental sustainability have become a dominant and urgent global concern. Understanding community perceptions leads to successful adaptation to climate change. This paper analyses community perceptions of climate change in selected Namibian regions. The study applied the qualitative research approach using the focus group discussion method. The data collection was conducted within a Socio-economic and Gender Analysis framework. The study has revealed that the communities are aware that the climate is changing due to changes observed in the past three to four decades. However, the study concluded that the communities do not have an adaptive capacity to respond to catastrophic natural disaster events such as the recurrent floods of 2009, ww & 2011. The study recommends a programme on community awareness regarding climate variability and change and its implications. The government in collaboration with communities and other relevant stakeholders should set up a long-term adaptation strategy for Namibia
An investigation into the information needs for poverty eradication at Greenwell Matongo in Katutura, Windhoek, in the context of the Millenium Development Goals (MDGs)
No full textThe Millennium Development Goals (MDGs) and the eradication of poverty ore two concerns that are highly supported by African governments, bilateral agencies and the United Nations. However within Africa, not much research has been done on what role libraries and information services can play towards meeting the goals of the MDG programme and the eradication of poverty. The aim of this paper is to present preliminary findings from a study in Greenwell Matongo, Katutura, Windhoek, on information needs for poverty eradication in the context of MDGs. Focus group discussions were conducted with three groups consisting of young females, young males, and adults respectively. The participants described the high levels of poverty in their community, and the low levels of hygiene and sanitation. There was recognition that education for children is important to overcome poverty. Gender relations are marked by alcohol related violence and rapes. The rate of HIV/A!DS and TB infection were thought to be high but kept secret because of fear of stigma. There were serious environmental problems in the community because of the use of inflammable fuel sources such as p araffin and candles in the corrugated iron shacks. The community information centre in the settlement is used intensively by young people for educational purposes, but only marginally, by adults for photocopying and literacy purposes. Recommendations are made on how to address the identified information needs of the community and capacity building in the context of MDG and poverty eradication
To live in the hearts of those we left behind is not to die
Get PDFThis paper discusses the issues that are conveyed by settlement lay-out and the meaning of space at the first mission station in South Africa, Genadendal. A historical archaeology appwach was used to collect data and analyse the remains building structures, materials and settlement lay·out that have survived at Genadenda/ in an attempt to make a case for c1 "Genadendal identity" and explain the cause for its continuity. The paper argues that the study of architectural structures and settlement /ay·out from an archaeological perspective can be viewed as an exercise in studying metapho1·s since the functional aspect of architecture is a result of" conscious reactions to physical needs" at a given time as Gribble (1998) writes. Such reactions are inevitably and subtly encoded in buildings and use of space. In addition, the paper demonstratc·s that the inhabitants of Genadendai mission str.ilion developed and exhibited a "Genadendal identify" through employing unique architectural technique' and conforming to a set of rules thot the missionories prescribed
The integration of an effective disaster risk reduction system in Namibia based on vulnerabilities of stakeholders in the Zambezi region
Get PDFNamibia has structures in place for disaster risk reduction. However, the need to mainstream the disaster risk reduction policy at all levels has been emphasised in the literature. The aim of this article is to present opportunities for the integration of effective disaster risk reduction in Namibia based on vulnerabilities of stakeholders in the Zambezi region. The data was collected by quantitative and visual research methods. The quantitative data was evaluated by means of the statistical package for social sciences and the visual data by semiotic analysis. In the opinion of members of civil society, the community and local government agencies, flooding is on the increase and losses in assets have been experienced. The Namibian disaster reduction system consequently faces a challenge. This study recommends an approach that is holistic, society that can act together in reducing disaster risks and facilitate community coalition