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Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The choice of the sample preparation technique used in combination with a chromatographic technique in environmental analysis strongly influences the performance of the method as a whole. The main aim of this work was to evaluate methods like: micro liquid-liquid extraction (цLLE)and solid phase micro extraction (SPME) in combination with gas chromatography-electron capture detector (GCECD) and a recently developed technique named stir bar sorptive extraction (SBSE) combined with thermal desorption system-programmable temperature vaporizationgas chromatography-mass spectrometer (TDS-PTV-GC-MS) for the analysis of organochloro-pesticides (OCPs) in natural water and to make a comparison between them. The most suitable method was then selected for the analysis of water samples collected from Eritrea. An additional goal was to develop a sensitive method for the analysis ofOCPs in soil and sediment samples. цLLE-GC-ECD and SPME-GC-ECD methods were evaluated for the analysis of OCPs in water. The former allowed achieving a sensitivity of less than 100 ppt and the latter was able to detect down to the 1 ppt level. Both methods were found to be repeatable with %RSD of3% to 19% and 5% to 12% as well as linear with a range of 1:103 and 1:5x103 respectivey. SBSE-TDS-GC-MS was also investigated for the analysis of OCPs in water samples. With this technique a good sensitivity down to 1 ppt was also obtained. The less sensitive nature of the MS compared to ECD was hereby compensated for by the large amount of polydimethylsiloxane (PDMS) phase on the stir bar. The method was repeatable and linear with a range of 1:5000, which is similar to the one obtained for the SPME-GC-ECD method. All three methods were also tested with real contaminated water samples and a comparison of the three techniques in terms of sensitivity, linearity, repeatability, availability and cost effectiveness was done. As a method of choice in terms of the above criteria, SPMEGC- ECD was applied to the water samples collected from Eritrea. The presence of some oePs such as a-BBC (benzenehexachloride), heptachlor, heptachlor epoxide, endosulfan I, p,p'-DDE (dichlorodiphenylchloroethylene), endosulfan II, p,p'-DDD (dichlorodiphenyldichloroethane), endosu!fan sulfate and p,p'-DDT (dichlorodiphenyltrichloroethane) in some of the Eritrean water samples was demonstrated The SPME-GC-ECD technique for the analysis OCPs in soil and sediment samples was investigated. It was shown to be able to detect down to 1 pg/g (lppt) with good linearity and repeatability. The method was also evaluated for authentic soil samples. Due to a lack of time the method could not be applied for the analysis of the soil and sediment samples collected from Eritrea. / AFRIKAANSE OPSOMMING: Die keuse van 'n gepaste monster-voorbereidingsmetode wat gebruik word tesame met 'n chromatografiese skeidingtegniek in omgewings-analise het 'n beduidende effek op die algehele metode. Die doel van hierdie werk was om metodes soos mikrovloeistof- vloeistof ekstraksie (цLLE) en soliede fase mikro ekstraksie (SPME) in kombinasie met gaschromatografie met elektronvangs deteksie (GC-ECD) te ontwikkel vir die analise van organochloor-pestisiede (OCPs) in natuurlike water. Vervolgens is hierdie metodes vergelyk met die onlangs-ontwikkelde roerstaaf sorptiewe ekstraksie tegniek (SBSE) in kombinasie met termiese desorbsie-GCmassaspektrometriese deteksie (TDS-GC-MSD). Die mees geskikte metode is vervolgens gebruik vir die analise van Eritreaanse watermonsters. Daarbenewens was die doelook om 'n sensitiewe metode te ontwikkel vir die analise van OCPs in gronden sedimentmonsters. Beide цLLE en SPME-GC-ECD metodes is gekarakteriseer deur goeie herhaalbaarheid en lineariteit. Die sensitiwiteit van bogenoemde metodes was minder as 100 dele per triljoen (ppt) en 1 ppt, respektiewelik. Ook met SBSE-TDS-GC-MSD kon 'n deteksielimiet van 1 ppt bereik word. In hierdie geval is vir die verlies van sensitiwiteit van die MSD in vergelyking met die ECD, gekompenseer deur die groter hoeveelheid PDMS op die roerstaaf in vergelyking met 'n SPME apparaat. Die herhaalbaarheid en lineariteit van die metode is vergelykbaar met dié van die SPMEGC- ECD metode. Al drie metodes is vergelyk vir die analise van gekontamineerde watermonsters in terme van sensitiwiteit, liniêre bereik, herhaalbaarheid, toeganklikheid en kosteeffektiwiteit. SPME-GC-ECD is vervolgens gekies as metode van voorkeur vir die analise van Eritreaanse watermonsters. Die teenwoordigheid van sekere OCPs soos a-BHC, heptachloor, heptachloorepoksied, endosulfan I, p,p'-DDE, endosulfan II, p,p' -DDD, endosulfan sulfaat en p,p' -DDT in die monsters is gedemonstreer. Die toepasbaarheid van die SPME-GC-ECD metode vir die analise van OCPs in grond-en sedimentmonsters is ook geëvalueer, en dit was moontlik om so min as 1 pg/g waar te neem. Weens tydbeperkings was dit nie moontlik om Eritreaanse grondmonsters met die ontwikkelde metode te analiseer nie.

Thesis (MPA)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The traditional skills required in government-wide local knowledge, sound political judgment and concern for the welfare of people-are still essential in the global information society. But, to be more effective, these skills now have to be supported by the new decision-making techniques of operations research and decision support systems. The capacity of the human mind to handle complex issues is limited. This situation of complexity and incapacity makes the application of operations research techniques and electronic DSS essential for good governance outcomes. Operations research is a multidisciplinary discipline that requires a team approach to decision making. It is based on systems analysis approach because of its preoccupation with interconnections among parts rather than within the parts themselves. This systems approach allows the optimization of an organization's overall goals, not just those of isolated departments. Optimization is one of the functions of operations research techniques. Linear programming models are most effective at the operational level of decision making with a single objective where scarce or limited resources must be allocated or used in an optimal manner. At the policy level where there are many uncertainties and conflicting objectives, multiobjective programming is more suitable. On the other hand, dynamic programming is flexible and is particularly applied whenever a sequence of decisions must be made and the goal is to find the combination of decisions that optimizes the overall effectiveness of the entire set of decisions. However, when a problem is too complex to be treated by numerical optimization techniques, simulation is used. That is when the problem either cannot be formulated for optimization, because the formulation is too large, there are too many interactions among the variables, or the problem is stochastic (probabilistic) in nature. Despite the analytical power of operations research, many real-world problems are not amenable to direct analytical solution by known mathematical techniques. Hence, in the absence of exact methods to solutions, we usually resort to heuristics, i.e. finding a good but not necessarily the best solution. Other problems encountered by public sector agencies include service stations (waiting lines), inventory levels, forecasting, and project scheduling, which all need decision support systems. To reduce the adverse impact of waiting to acceptable levels one has to minimize costs associated with providing service and those associated with waiting time. For smooth operations, inventory of goods must be kept to an acceptable level to minimize setup or ordering, inventory holding, and shortage (public complaints, and loss of good will and sales) costs. Forecasting is crucial as most managerial decisions are based on projected information and policy analysis is almost always about future outcomes. Many government policies and programs are implemented through projects. Project managers must know how long a specific project will take to finish, what the critical tasks are, and what the probability of completing the project within a given time span is. Successful applications of operations research and decision support systems in the public sector have been recorded including in the areas of the military, transportation, crime and justice, police units, energy, natural resources, facility location, and land use planning. However, operations research applications are not without impediments. Technical and institutional barriers are some of the problems encountered in the effort to apply operations research in the public sector. Similarly, reasons for the slow growth of decision support systems include lack of user demand, lack of system designer motivation, lack of system designer expertise, reluctance to change, and increased risk of failure In the Eritrean public sector, the low level of awareness of operations research and decision support systems is reflected in the inadequacy of addressing multicriteria decision processes, the lack and lor inappropriate selection of decision support systems, improper project management techniques, suboptimal facility locations and service stations, the low level of multidisciplinary approach, and the absence of national standards for pollution control. In general, constraints such as the lack of capacity, awareness, know-how, and software, are rampant. The study concludes that policy-making processes should incorporate opportunities to exercise choices and explore rational options. These rational options are the results of appropriate interface of human, operations research and decision support systems. / AFRIKAANSE OPSOMMING: Die tradisionele vaardighede wat van 'n regering verwag word - wye kennis van plaaslike omstandighede, goeie politieke oordeel en besorgdheid oor die welvaart van mense - was nog altyd belangrik in die moderne wêreld. Hierdie vaardighede moet egter ondersteun word deur die nuwe besluitnemingstegnieke van operasionele navorsing en besluitnemings ondersteuningstelsels om effektief te wees. Die vermoë van die menslike brein om komplekse kwessies te hanteer, is beperk. Hierdie situasie van kompleksheid aan die een kant en onvermoë aan die ander kant maak die aanwending van operasionele navorsingstegnieke en elektroniese besluitneming nodig vir goeie regeringsuitkomste. Operasionele navorsing is 'n multidisiplinêre disipline wat 'n spanbenadering tot besluitneming benodig. Dit is baseer op die sisteemanalise benadering omdat dit gaan oor interkonneksies tussen onderdele en nie soseer oor die onderdele self nie. Hierdie sisteembenadering maak die optimisering van die sisteem se oorhoofse doelwitte moontlik, nie net die doelwitte van geïsoleerde departemente nie Optimisasie is een van die funksies van operasionele navorsing. Liniêre programmeringsmodelle is meer effektief op die operasionele vlak van besluitneming met 'n enkel doelwit waar skaars of beperkte bronne toegewys of gebruik moet word op 'n optimale wyse. Op die beleidsvlak waar baie onsekerhede en botsende doelwitte voorkom, is multi-doelwit programmering meer geskik. Aan die ander kant is dinamiese programmering meer toepaslik en buigsaam, veral as dit toegepas word waar 'n reeks besluite geneem moet word en die doel is om 'n kombinasie van besluite te vind wat die oorhoofse effektiwiteit van die hele stel besluite optimiseer. Sekere probleme is egter te kompleks om met numeriese optimisering op te los, omdat die probleem nie geprogrammeer kan word vir optimisering nie, omdat die formulasie te groot is, daar te veel interaksies tussen die veranderlikes is, of die probleem stogasties van aard is. Dan kan simulasies oorweeg word om oplossings te probeer vind. Ten spyte van die analitiese krag van operasionele navorsing, kan baie werklike probleme nie direk deur analitiese wiskundige tegnieke opgelos word nie - altans nie deur bekende wiskundige tegnieke nie. As 'n presiese oplossing nie moontlik is nie, kan kan 'n heuristiese oplossing ondersoek word, d.w.s. 'n goeie, maar nie noodwendig die beste oplossing nie. Ander probleme wat deur die openbare sektor ondervind word, sluit in diensstasies, inventarisvlakke, voorspellings, en projekskedulering. Hulle benodig almal besluitnemingsstelsels vir effektiewe oplossings. Om die wagtydperk te verminder tot 'n aanvaarbare vlak moet die koste verbonde aan die verskaffing van die diens en die koste verbonde aan wagtydperke minirniseer word. Om 'n operasie glad te laat verloop moet die inventaris van goedere op 'n aanvaarbare vlak gehou word om die koste van bestellings, die byhou van voorrade en tekorte (klagtes van die publiek, die verlies aan vertroue en verkope) te minirniseer. Voorspelling is van die uiterste belang vir hierdie doel, omdat bestuursbesluite baseer is op geskatte syfers en beleidsontleding betrekking het op toekomstige uitkomste. Baie regeringsbeleide en -programme word deur projekte geïmplementeer. Projekbestuurders moet weet hoe lank dit sal neem om 'n projek te voltooi, wat die belangrike take is en hoe waarskynlik dit is dat die projek betyds voltooi sal word. Operasionele navorsing en besluitnemingsondersteuning stelsels is al suksesvol aangewend in die volgende openbare sektore: militêre funksies, vervoer, misdaad en justisie, die polisie, energie, natuurlike hulpbronne, en die beplanning van grondgebruik. Tegniese en ander hindernisse word egter soms ondervind by die gebruik van operasionele navorsingstegnieke in die openbare sektor. Redes hoekom die gebruik van sulke stelsels so stadig toeneem, sluit in die gebrek aan aanvraag van verbruikers, die gebrek aan stelselontwerp motivering, die gebrek aan stelselontwerp vaardighede, onwilligheid om te verander en die groter risiko van mislukking. In die openbare sektor van Eritrea word die lae vlak van bewustheid van operasionele navorsing en besluitnemingsondersteuning stelsels gereflekteer in 'n onvermoë om dit te gebruik, die gebrek aan of verkeerde keuse van sulke hulpmiddels, verkeerde bestuurstegnieke, suboptimale plasing van dienspunte, die afwesigheid van multi-disiplinêre benaderings, en die afwesigheid van nasionale standaarde vir die beheer van besoedeling. Beperkings soos 'n gebrek aan kapasiteit, bewustheid, kennis en sagteware kom algemeen voor. In hierdie studie word daar tot die gevolgtrekking gekom dat beleidmakende prosesse die geleentheid behoort in te sluit om keuses te maak en om verskillende opsies te toets. Hierdie rasionele opsies is die gevolg van die regte interaksie tussen die mens, operasionele navorsing en besluitnemingsondersteuning stelsels.

An integrated approach with remote sensing, GeographicInformation Systems (GIS) and more traditional fieldworktechniques was adopted to assess the groundwater potential inthe central highlands of Eritrea. Digitally enhanced colorcomposites and panchromatic images of Landsat TM and Spot wereinterpreted to produce thematic maps such as lithology andlineaments. The potential of the Advanced Spaceborne ThermalEmission and Reflection Radiometer (ASTER) data forlithological and lineament mapping was evaluated. Topographicparameters such as surface curvature, slope and drainagesystems were derived from digital elevation models and used tomap landforms. Digital elevation models (DEM) derived fromcontours and acquired in the Shuttle Radar Topographic Mission(SRTM) were compared in relation to location, drainage networksand lineament extraction. Fracture patterns and spacing weremeasured in the field in different rock types and compared withlineaments. Selected springs and wells were visited to studytheir topographic and hydrogeological setting. Well logs,pumping tests, water table depth in dry and wet season as wellas location of wells were collected. All thematic layersincluding hydrogeological data were integrated and analysed ina geographic information system. A groundwater potential mapwas generated and compared with yield data. Groundwaterrecharge was estimated based on water level fluctuations inlarge dug wells and chloride mass-balance method. Principal component analysis for rock type mapping providedbetter results with ASTER than with Landsat TM data. DEM datapermitted to create detailed landform maps useful torgroundwater potential assessment. DEM derived from SRTM dataare better for detection of drainage systems and linearfeatures than those derived from contours. Most of the fracturesystems corresponding to lineaments are either extensionalrelated to normal faults and dykes, or shear fractures relatedto strike-slip faults. N-S, NW-SE, WNW-ESE, NE-SW and ENE-WSWare dominant fracture orientations with often very densespacing. High yielding wells and springs are often related tolarge lineaments and corresponding structural features such asdykes. Typically wells and springs in basaltic areas havehigher yields mainly due to primary joints. Young alluvialsediments with high permeability and deeply weathered rocklayers are important for water supply especially in hydraulicconnection with fracture systems in crystalline bedrock.Groundwater potential zones demarcated through the model are inagreement with bore well yield data. The spatial distributionof groundwater potential zones shows regional patterns relatedto lithologies, lineaments, drainage systems and landforms.Recharge rates of 10 - 50 mm were estimated in this region. Theresults demonstrate that the integration of remote sensing,GIS, traditional fieldwork and models provide a powerful toolin the assessment and management of water resources anddevelopment of groundwater exploration plans. <b>Key words:</b>Remote sensing, Geographic InformationSystems, groundwater, geomorphology, Digital elevation model,lithology, hard rock, lineament, structures, hydrogeology,Eritrea

Presented in this thesis are some basic concepts and applications of seismic hazard analysis and the elements that influence the amplitude and geometric attenuation of earthquake ground motion. This thesis centers on the identification of the styles of failure, focal mechanisms, and the state of regional stress in the study area. Seismic hazard is a complex problem often involving considerable uncertainties. Therefore it is reasonable to consider different seismic hazard analysis approaches in order to as robustly as possible define zones of different levels of hazard. With the aim of characterizing and quantifying hazard in the east African region of Eritrea and its surroundings, a study is included in the thesis presenting hazard maps constructed using two non-parametric probabilistic seismic hazard analysis (PSHA) approaches. Peak ground acceleration (PGA) values for 10% probability of exceedence in 50 years are computed at given grid points for the whole selected area and results from both methods are compared. Other aspects addressed in the thesis include the determination of source parameters of selected earthquakes that occur in the Afar region. The styles of faulting, the mechanisms involved during the rupture process and the states of stress along the major tectonic features are also highlighted. Source parameters for selected events in the region were re-evaluated and improved solutions obtained. An aftershock sequence in the Hengill volcanic area in SW Iceland, following the major event that occurred on June 4, 1998, was used to investigate improved methodologies for moment tensor using a relative approach. The sensitive and spatially dense seismic network in this area reveals large sets of clustered events allowing the power of the new methodology to be demonstrated and providing greater insight into the tectonic implications of the activity in the area.

<p>An integrated approach with remote sensing, GeographicInformation Systems (GIS) and more traditional fieldworktechniques was adopted to assess the groundwater potential inthe central highlands of Eritrea. Digitally enhanced colorcomposites and panchromatic images of Landsat TM and Spot wereinterpreted to produce thematic maps such as lithology andlineaments. The potential of the Advanced Spaceborne ThermalEmission and Reflection Radiometer (ASTER) data forlithological and lineament mapping was evaluated. Topographicparameters such as surface curvature, slope and drainagesystems were derived from digital elevation models and used tomap landforms. Digital elevation models (DEM) derived fromcontours and acquired in the Shuttle Radar Topographic Mission(SRTM) were compared in relation to location, drainage networksand lineament extraction. Fracture patterns and spacing weremeasured in the field in different rock types and compared withlineaments. Selected springs and wells were visited to studytheir topographic and hydrogeological setting. Well logs,pumping tests, water table depth in dry and wet season as wellas location of wells were collected. All thematic layersincluding hydrogeological data were integrated and analysed ina geographic information system. A groundwater potential mapwas generated and compared with yield data. Groundwaterrecharge was estimated based on water level fluctuations inlarge dug wells and chloride mass-balance method.</p><p>Principal component analysis for rock type mapping providedbetter results with ASTER than with Landsat TM data. DEM datapermitted to create detailed landform maps useful torgroundwater potential assessment. DEM derived from SRTM dataare better for detection of drainage systems and linearfeatures than those derived from contours. Most of the fracturesystems corresponding to lineaments are either extensionalrelated to normal faults and dykes, or shear fractures relatedto strike-slip faults. N-S, NW-SE, WNW-ESE, NE-SW and ENE-WSWare dominant fracture orientations with often very densespacing. High yielding wells and springs are often related tolarge lineaments and corresponding structural features such asdykes. Typically wells and springs in basaltic areas havehigher yields mainly due to primary joints. Young alluvialsediments with high permeability and deeply weathered rocklayers are important for water supply especially in hydraulicconnection with fracture systems in crystalline bedrock.Groundwater potential zones demarcated through the model are inagreement with bore well yield data. The spatial distributionof groundwater potential zones shows regional patterns relatedto lithologies, lineaments, drainage systems and landforms.Recharge rates of 10 - 50 mm were estimated in this region. Theresults demonstrate that the integration of remote sensing,GIS, traditional fieldwork and models provide a powerful toolin the assessment and management of water resources anddevelopment of groundwater exploration plans.</p><p><b>Key words:</b>Remote sensing, Geographic InformationSystems, groundwater, geomorphology, Digital elevation model,lithology, hard rock, lineament, structures, hydrogeology,Eritrea</p>

No abstract available. / Thesis (M.PH.)-University of KwaZulu-Natal, 2004.

The main focus of this study is on the causes of the problems in English language proficiency of Grade Nine high-school learners in Asmara, Eritrea, with reference to their oral skills, particularly for academic purposes. This study examines the way Grade Nine English teachers in Eritrea do or do not promote the development of Grade Nine learners' oral proficiency. The researcher's focus is on how the teachers structure their teaching approach to English and the way students learn the language in the classroom. The researcher looked at the practices of English language teachers by conducting observations in English classes in two high schools in Eritrea for about a month. The researcher obtained rich data via different methods of data collection with respect to the learners' oral development. The criteria that the researcher adopted for observation were those of the Communicative Orientation of Language Teaching Observation Scheme (COLT) (Allan, Frohlich, and Spada: 1983). In addition to the classroom observation, the researcher also conducted interviews with the teachers. Questionnaires were distributed to learners, after which focus-group discussions with selected students were conducted. The findings of this study are summarized as follows. Firstly, English teachers have teaching techniques which are ineffective in achieving the intended objective. They use the structural approach to language teaching, which is out-dated. Secondly, grammar is the main focus of lessons. Most of the students commented that more oral (speaking) classes should be included in the learning of language to achieve oral/aural proficiency. Teachers must therefore foster a supportive classroom environment and stress the importance of oral classes in language learning. / Thesis (M.A.) - University of KwaZulu-Natal, Pietermaritzburg, 2004.