Department of Civil and Mining Engineering

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Assessment of floodwater harvesting infrastructures in the Namibian Cuvelai-Etosha basin
(University of Namibia, 2020) Niipare, Emeritha
The Cuvelai-Etosha Basin lies in north-central Namibia and due to the prevailing climatic situation, the basin is dominated by strong seasonal and annual variations of either very dry conditions with drought or heavy flooding in certain years. A growing population in the Cuvelai-Etosha Basin has resulted in increased demand for water for daily use and agricultural activities. Floodwater Harvesting Infrastructures are considered to be a more effective way to solve those problems. Hence the current status of the initiatives taken to harvest floodwater for use in the dry seasons needs to be determined by means of remote sensing, secondary data and field validation. The main objective of the study was to assess the condition and performance of Floodwater Harvesting Infrastructures in the Cuvelai-Etosha Basin. The Ministry of Agriculture, Water and Forestry constructed 34 earth dams in this Basin from 2008 to 2011. Out of these newly constructed earth dams, 18 were randomly selected for the study. The research design was based on using both qualitative and quantitative data on a completely randomised basis. Sentinel data was used to identify the water bodies by means of remote sensing. Information was gathered by means of structured interviews from the locals or people acquainted with the sites. The results from the interviews taken among 96% of the participants showed that the highest usage of earth dams is livestock watering while few people use them for irrigation purposes. Due to sedimentation in the earth dams, depth has reduced and surficial area has increased; hence the dams can no longer retain the quality and quantity of water they were designed for. In conclusion, the method developed from GIS successfully identified 94% of the existing earth dams.
Assessment of hydraulic performance of the Eastern National Water Carrier, Namibia: Flumes three to four
(University of Namibia, 2019) Mutelo, Mukendoyi A.
In response to drought impacts, water augmentation by developing more boreholes in the Grootfontein-Otavi karst area and increase the use of the Eastern National Water Carrier (ENWC) was prioritised. Hence, plans to increase water transportation should be based a sound understanding of the hydraulic behaviour of the ENWC. Thus, this study sought to utilise the HECRAS model for the primary objective of assessing the hydraulic performance of the section between flumes 3 and 4 i.e. evaluating the hydraulic behaviour of the ENWC and determining its maximum water transportation capacity using HEC-RAS as well as perform a rough estimate of leakage and evaporation losses. The results show that the mean Manning's roughness coefficients n = 0.099, 0.124, 0.028 and 0.038 were respectively found in Canal! and 2, and Siphon land 2. An assessment of observed and the predicted water depth exhibited a very good agreement, that yielded an R2 = 0.997. The estimated maximum capacity of the canal system between flumes 3 and 4 was found to be discharge Q = 0.3 m3/s while the flows accommodated in different sections of the canal ranged from Q = 0.3 to 1 m3 /s. A variation of the roughness coefficients did not seem to noticeably alter the estimated maximum capacity or influence the water levels of the normal flow regimes. With respect to leakage losses, the majority of canal sections i.e. Canal 1, Siphon 1 and Siphon 2, bad leakage losses of the order of20% or more of mean discharge in those respective sections. Therefore, it can be deducted that the hydraulic state of the aqueduct is undesirable when compared to the roughness condition n = 0. 015 of concrete-lined aqueducts. Hence robust strategies for operation and maintenance of the aqueduct are required.
Assessment of the impact of Namibian rural road characteristics on crash incidence
(2020) Ambunda, Robert; Johannes, Petrina
Road user perceptions and roadway design elements play a vital role in determining the crash risk level on the roads. The study investigated factors that play a prominent role in causing road traffic crashes on rural roads on the Namibian road network. The study found that animals and pedestrians were the highest cause of road traffic crashes on the study sections. The high volume of vehicles traversing the roads section combined with the lack of appropriate barriers to separate traffic from the high presence of animals and pedestrians along the study section contributed to the hazardous safety situation on the road. The study identified that drivers losing control of vehicles on the study sections was one of the highest cause of traffic crashes. Speeding combined with negative design of various road elements directly impacts driver perceptions of the road environment and misleads road users, thereby leading to human errors that influence the frequency and severity of road crashes on the study section. The study identified under-reporting and misinformation on road crashes as some of the factors impeding the development of a vivid picture on the actual scale of the road safety problem on Namibian rural roads. The analysis of the road crashes will assist and enable road safety stakeholders in identifying, developing and implementing appropriate safety measures to sustainably address the road safety issue on Namibian roads. In addition to the road safety assessment, a road design audit carried out on the study section found that the shoulder grade and lane widths did not comply with the Technical Recommendations for Highways 17 on the Geometric Design of Rural Roads in Namibia. The study therefore developed multivariate road crash models using Negative Binomial Regression to investigate the extent of the link between road crash rates of various severity and the road design elements. The models identified several interactive relationships between lane widths, shoulders widths, 85th operating speed and horizontal curve radii on the section that significantly influenced crash rates on the roads.
Assessment of the impact of urban development on flood peaks in the Acacia surburb, Arebbusch sub-catchment Windhoek, Namibia
(University of Namibia, 2019) Coetzee, Dirk Jones
Climate change is affecting global weather patterns, more so by exacerbating the sporadic nature of Namibia’s rainfall patterns. This has negative consequences on urbanization as increased rainfall in certain rainy seasons coupled with increased urban development could lead to dangerous flooding in low-lying areas, as was the case with Acacia residential, Windhoek, in 2004. Increased urban development has the potential to increase runoff and flood peaks by 20% to 50% of those under natural conditions. This study investigated the urban development in the greater Arebbusch catchment, and its impact on the Acacia suburb. Employed methods and techniques comprised remote sensing, GIS, SANRAL Drainage manual and hydraulic modelling software (HEC-RAS). Landsat and Sentinel images were used to produce and determine land cover changes in the study area between 1989 and 2018, respectively. Furthermore, computer models of the Acacia River section, the steady and unsteady flow simulations and flood inundation area were carried out in the Acacia residential area and compared with the existing, regulatory 1:50-year flood line that the City of Windhoek uses as reference for urban development. Results indicate that the flood peaks in the study area increased by 13% over the past 30 years. This suggests that urban development influenced flood peaks in the study area, whilst the 1:50-year flood line remains static. It is therefore recommended that more assessment be done on the hydraulic flow of all constructions in close proximity to the 1:50-year flood line, whilst taking into greater consideration the accumulative effects of urban development on urban flood peaks.
Cryptosporidium screening of selected water resources of the Cuvelai-Etosha basin and Kunene basins and implications for water management
(University of Namibia, 2019) Muhenje, Swanu
In the Cuvelai-Etosha and Kunene Basins, a remarkable percentage of the population depends on a variety of unprotected water resources for both domestic and livestock purposes, which includes Earth dams, wells, boreholes and streams. Waterborne transmission of Cryptosporidium could be prevalent in water basins were water resources have no protection against direct-microbial contamination. However, little is known about the influence of management of water resources on Cryptosporidium prevalence. The main objective of this study was to assess the prevalence of Cryptosporidium in selected water resources of the Cuvelai-Etosha and Kunene basins and assess the implications of findings on water management. On-site parameters of conductivity, dissolved oxygen, temperature and pH were measured from a total of 47 water samples from 47 sampling sites were screened for Cryptosporidium at the end of the rainy season by quantitative polymerase chain reaction (qPCR). The results showed a prevalence of 4.3 %, all from unprotected water resources which suggest that management (protection) of water resources from direct access to animals and direct-runoff is essential to lower the risk of waterborne infection of cryptosporidiosis. We recommend source protection of water resources in the basins to lower the risk of Cryptosporidium contamination. Further longitudinal studies screening for Cryptosporidium should be conducted to assess prevalence.
Factors affecting the adoption of sustainable water conservation practices in smallholder farming systems: A case study of smallholder farmers in Omusati region, Namibia
(University of Namibia, 2020) Amukuhu, Bernadette N.
Namibia is the driest country in Sub-Saharan Africa and water shortage remains a serious challenge in agricultural productivity. Smallholder farmers in rural areas are often advised to adopt sustainable water conservation practices aimed to counter these challenges. However, the adoption of such practices among smallholder farmers is far below the expectations. Hence, this study was conducted to examine the current sustainable water conservation practices used by smallholders and what influential factors affect adoption of the introduced water conservation practices. A random sample of 30 smallholder farmers from six constituencies in Omusati Region was used. Field observation and a two-part questionnaire were used to collect data used in examining the level of water conservation adoption and to profile smallholder farmers. Descriptive and analytical statistics were used to analyse the collected data. The study showed that some sustainable water conservation practices such as ripping, planting basins, compost and drip irrigation were being adopted. ANOVA test results indicated that education status and farming experience of household heads have a significant impact on adoption rate of the introduced sustainable water conservation practices. Conversely, family size per household, farm size or cultivated land and the age of household heads have no significant effects on the adoption of sustainable water conservation practices. The challenges affecting smallholder’s adoption of sustainable water conservation practices include lack of farm implements, lack of water conservation awareness, climate characteristics, lack of funds, shortage of farm labour, lack of water conservation knowledge, limited farmland for cultivation and lack of extension services and institutional supports. Based on the study findings its thus recommended that the Ministry of Agriculture, Water and Forestry and other concerned bodies should consider the identified influential factors and challenges to improve the situation and enhance the adoption of introduced water conservation practices.
Performance evaluation and redesign of waste stabilization ponds for the treatment of wastewater in Ongwediva
(University of Namibia, 2018) Rukoro, Oriri
The existing Ongwediva Waste Stabilization Ponds have had several problems in their operations over the past years. Thus, the treatment performance of the waste stabilization ponds was assessed in terms of the reduction efficiency of some physical, chemical and biological pollutants of importance. Data were collected daily from May to June 2017 and analyzed for both raw and treated wastewater. Results of these investigation showed that the average effluent concentrations of BOD, DO, TSS FC, nitrate, nitrite, ammonia, pH, EC and turbidity taken at the secondary facultative pond were 22.07mg/l, 1.91 mg/l, 21.73 mg/l, 2×105 counts/100 ml, 2.33 mg/l, 0.39 mg/l, 0.74 mg/l, 7.64, 16.67 NTU and 98.52 mS/m respectively. The results also indicated that the average effluent concentrations of BOD, nitrate, nitrite, ammonia, TSS and pH complied with the Namibian treated wastewater standards for disposal. However, FC, EC, TDS and turbidity exceeded their maximum permissible limits. The lowest overall efficiencies were for EC, TDS and FC of 5.05%, 5.12% and 20% respectively. Hence the addition of two maturation ponds of size 5408m2 as a final stage of OWSPs. The design of facultative ponds can also be modified by adding additional entrances of wastewater to the ponds to make complete mix in the ponds.
The use of life cycle cost analysis in determining the cost effectiveness of railway lines' design and maintenance options for railway lines through windblown sandy desert in Namibia: Case study of the Aus - Luderitz railway line
(University of Namibia, 2019) Hamalwa, Jonas
Railway transport in Namibia is one of the most important mode of transport with great importance to the economy of the country. Currently, road networks are the most important because of the low population density of the nation. However, railway lines have been reported to be the most economical, efficient, environmentally friendly, and the safe solution for long distance transportation of heavy goods [1]. The Namibian Railway Network lines linking to the coastal towns and ports, i.e. Swakopmund-Walvis Bay and Aus-Lüderitz Railway Line, are passing through the Namib Desert. Deposit of wind-blown sand onto the railway lines poses a great challenge to the maintenance and operations of this lines. The challenge for decision-makers is which solution is cost-effective to implement in the Namibia context to solve the problem. It has been reported widely [2, 3, 5, 7] that the best way to evaluate the cost effectiveness of different solution is by using the Life Cycle Cost Analysis (LCCA) approach. The main objective of this study is to use LCCA, as an engineering economic tool, to determine the cost-effectiveness of the options to the challenging wind-blown sand on the railway lines passing through the desert. Specific objectives are: 1) Identify the best infrastructure design options and technical maintenance solutions for mitigating the sand problem onto the tracks. 2) Use the LCCA to evaluate the cost-effectiveness of the different solutions in order to recommend the best strategy. The study has exploded the knowledge of the LCCA of railway infrastructure in Namibia for both the analysts and decision-makers. This study has presented a good insight of the LCCA as one of the best systematic approach to use to guarantee the best performance of the railway system. Ultimately the LCCA was successfully employed in the study to determine the cost-effectiveness of the solution(s) to combat the challenge of sand ingress onto the railway line. In the LCCA process, different alternatives were identified, discussed and analysed; which includes both railway infrastructure design solutions and technical mitigation measures. The LCCA results presented the Humped Slab Track to be the cost-effective solution compared to all other alternatives. However, it was further discussed that this option is only ideal for the sections where dynamic dunes are not crossing. This has proven that in as much as LCCA is a good engineering economic tool, it needs to be coupled with viability criterion/criteria in order to determine the cost-effectiveness of the design and maintenance solutions to combat the challenging problem of wind-blown sand on the railway line passing through desert areas. The study further proved that Tubular Track system was cost-effective compared to the Conventional Track system. The study provides a good insight of analysis to prove that Tubular Track system covered in the Tunnel System is the most viable and cost-effective solution to the sand problem along the dune belt. A number of recommendations for future improvement(s) and further researches were also proposed.
Water resources governance in the upper Swakop basin of Namibia
(University of Namibia, 2018) Pazvakawambwa, Godfrey T.
This dissertation examined and presented adaptive water governance analysis and tools for the Upper Swakop Basin (USB) in Namibia where integrated river basin management is still in its infancy. The water governance concerns in the basin include pollution monitoring and control challenges that are further threatening the security and adequacy of the developed drinking water sources. By applying and triangulating different methods (models, statistical analysis, quantitative and qualitative measures etc.), this study uniquely analysed the water governance issues in the Upper Swakop Basin. The objectives of the study were to assess the water quality at potential pollution sources and at major receiving waters in the Upper Swakop Basin based on secondary data obtained from key stakeholders; to evaluate the adequacy and availability of drinking water sources in the USB; to assess the ethical, social and acceptability perceptions of water reuse for potable purposes based on primary data obtained from a purposive stakeholder survey; to qualitatively assess water governance structures and participation as well as to evaluate overall water governance processes and outcomes in the USB. Water quality parameters were assessed using descriptive statistics, extreme value analysis, spatial analysis and some of the parameters were compared to those given in the water quality regulations and standards of Namibia using ANOVA. The adequacy and availability of water was assessed using the simple water balance method, the Box-Jenkins ARIMA time series forecasting models, and the WEAP model. The ethical, social and health acceptability views and perceptions on water reuse for potable purposes were assessed using frequency tables, charts, and graphs. Stakeholder participation was analysed using scenario workshops, mediated modelling and social multi-criteria evaluation methods and was based on the ADVISOR framework. The researcher developed the 7”I”s water governance tool which was used to map stakeholders and to assess the overall water governance performance of the USB. The study found that water pollution parameters values were extremely high for agro-industries. Moreover it was found that the developed water resources supplying the USB are inadequate especially in Windhoek where additional drinking water sources outside the USB are required to augment its demand of 26.7 Mm3 per annum in 2015 to a projected amount of 52.93 Mm3 per annum in 2050. Acceptability levels of water reuse for potable purposes were found to be moderate. Stakeholder participation in water governance needs to be more inclusive. The existing legal and institutional framework for water governance was found to be inadequate due to lack of implementing technical capacity (in terms of personnel, technical skills, database management and information sharing). One of the unique contribution of the study to new knowledge is the development of the 7”I”s evaluation tool for overall water governance performance which can also be used in other similar basins. The pollution extreme parameter values assessment is proposed as a quick and initial evaluation of any problematic river catchment and to take remedial measures on would be polluters. Proper water pollution control and compliance strategies should be stepped up for agro-based industrial landuses. Landuse based water governance policy interventions may be required to prevent water pollution on the Swakoppoort Dam. The study proposed a new concept of utilizing the smaller already polluted Goreangab Dam, which receives polluted water from Windhoek and is situated upstream of Swakoppoort Dam, as a pollution detention and check dam as well as a clean-up dam for the downstream dam. A study on the feasibility of this new concept should be carried out. If the concept proves to be successful, it could be used to solve the problem of polluted dams downstream of “city river catchments” elsewhere. The time series of the rainfall in Windhoek area was stationary. This could mean climate change might have had little effect on Windhoek rainfall for the past 121 years. Therefore the study recommended more adaptive water resource planning, multi-source optimization and water governance initiatives of exploring the available secondary sources for the sustainable development of the USB. Water security in the USB can be enhanced by optimizing the Windhoek Rechargeable Aquifer Storage capacity. Institutions that supply bulk water to Windhoek can be unified into a single water governance institution to optimize and integrate these multiple sources. Based on adaptive water governance resource planning and multi-source optimization, the study further proposed a basin management strategy to ensure suitable water quality and quantity and to build adequate technical capacity.

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