As part of the new navigation lock for Bonneville Dam a new water source for the Bonneville Fish Hatchery must be supplied. The hatchery is located on the Oregon side of the Columbia River downstream of the dam. It requires large quantities of water free from chemical and biological contamination. In addition, the water has to be in a narrow temperature range. Currently the fish hatchery receives its water from a well field that is located on the alluvial terrace downstream of Bonneville Dam. The well field lies in the proposed approach channel for the new lock and has to be abandoned during construction of the lock. For the continued water supply of the hatchery, a new well field will be developed north of the approach channel. Early in the planning phase for the new lock, concerns were raised about the potential impact of the relocation of the well field and the excavation of the new approach channel on the hatchery. To assess these concerns and to assure a continuous water supply during and after construction, a hydrogeologic investigation was initiated. Within the framework of the investigation this study focuses on the analysis of pumping test data and the development of a three-dimensional ground water flow model for the site. In the first phase of the study, data from eight pumping tests were analyzed. Hydrogeologic properties of the sedimentary units that make up the downstream terrace were determined. The focus was the pre-slide alluvium (PSA) aquifer, the water source for the existing and the future well field. In addition, the nature and location of hydrogeologic boundaries for the ground water system were determined. The results, in conjunction with information from subsurface exploration and laboratory tests, were used to develop a conceptual understanding of the ground water system at the site. The PSA aquifer receives its recharge primarily from leakage through the overlying confining layers over a large area. A direct connection between the Columbia River and the PSA aquifer could not be detected. They appear to be separated by a continuous aquitard layer or by a layer of fine-grained sediments on the river bottom. Based on these findings, in the second phase of the study, the ground water modeling program HST3D (Kipp, 1987) was used to develop a three-dimensional ground water model for the site. The model was calibrated with data from one of the pumping tests. The calibration was then verified with a second set of conditions including pumping from shallow and deep wells. Water levels in the deep PSA aquifer and the shallow unconfined aquifer were successfully matched. A satisfactory match of observed conditions was possible with only slight modifications of the hydrogeologic parameters determined by pumping test analysis and based on the conceptual model developed in the first phase of the study. It appears that a continuous aquitard layer separating the Columbia River and the PSA aquifer, with the aquifer receiving recharge through vertical leakage over a large area, is a valid representation of the aquifer system.

A population survey was conducted on Galago moholi along the road system at Loskop Dam Nature Reserve, Mpumalanga province, South Africa. The data were analyzed using the maximum perpendicular distance, mean perpendicular distance, and maximum reliable perpendicular distance methods. Vegetation sample plots were constructed at the location of each individual sighted in order to analyze the species’ habitat use. The results indicate that the species density of G. moholi is significantly lower at Loskop Dam Nature Reserve than previously reported at other sites within South Africa. G. moholi was found to prefer areas with high concentrations of Dichrostachys sp., Combretum sp., or Acacia sp. One individual was observed consuming vegetative matter, which may indicate that the population within the reserve is utilizing available resources in a different way than populations in other parts of southern Africa. / Department of Anthropology

As part of a vegetation survey program for the newly acquired farms incorporated into the Loskop Dam Nature Reserve, the vegetation of the Hondekraal Section was investigated. The study provides an ecological basis for establishing an efficient wildlife management plan for the Reserve. From a TWINSPAN classification, refined by Braun-Blanquet procedures, 12 plant communities, which can be grouped into eight major plant communities, were identified. A classification and description of the major plant communities are presented as well as a management plan. Descriptions of the plant communities include characteristic species as well as prominent and less conspicuous species of the tree, shrub, herb and grass strata. This study proves that the extended land incorporated into the Reserve contributes to the biological diversity of the Reserve. / Environmental Sciences / M. Tech. (Nature Conservation)

M.Sc. / There are 39 known species of Lamproglena to date. A review of all species including the species name, the author, as well as an accompanying sketch and information regarding the distribution, pathology and host preference is given. Lamproglena clariae is a copepod gill parasite found on Clarias gariepinus. It has been observed that they cause extensive gill tissue proliferation, which may interfere with respiration. It is uncertain on which tissue type Lamproglena feeds, as red blood is never apparent in the gut of Lamproglena monodi, whereas in the cases of both L. clariae and L. barbicola they undoubtedly feed on blood, proven by the frequently blood-filled gut. Even thought the mouthparts are not fully understood as yet, it is deduced that feeding involves only the maxillae and maxillipedes. Many poecilostomes lacks mandibles. Also, in the lernaeids the mandible is appendage is the smallest and from the 39 known Lamproglena species, the mandibles are described in only eight species. This study examines the digestive tract and the structure of the mouthparts using both light and scanning electron microscopy and tracts the nerves to establish if L. clariae does possess mandibles. Specimens were collected from Clarias gariepinus in the Vaal Dam after the fish were euthanised and the gills removed. The samples were fixed in an aceto formaldehyde alcohol solution and preserved in 70% ethanol prior to dehydration and embedding in resin. Serial section were made at 5 pm and stained with a trichrome stain. A schematic as well as graphic reconstruction of the digestive system is presented. The digestive system consist of three predominant parts, the fore, mid and hindguts. The foregut has a cuticularised epithelium. The oesophagus has a muscle layer iv which stretched and contracts in order to aid feeding and it extends into the midgut via a funnel-like structure. There are four designated zones within the midgut. The hindgut is a simple, cuticle lined tube. Cell structures are discussed. The bilobed protocerebrum in L. clariae is present. The deutocerebrum innervates the antennules. The tritocerebrum consist of two lobed parts and innervates the antennules. The ventral nerve cord is situated posterior to the cephalon. It protrudes dorsally, from where the posterior commissures innervates. The anterior commissures innervates closer to the tritocerebrum. The nerves leading to the mandibles are innervated from the anterior commissure. The more posteriorly located commissure innervates the nerve to the seta located between the antennae and the maxillae. Both the nerves to the maxillae and the endopodite to the maxillae are innervated from this commissure. Mandibles were left out of previous species descriptions of L. clariae. Other Lamproglena species descriptions, showing the mandibles, revealed slender looking mandibles located in close proximity to the mouth opening. This is contrary to the stout mandibles of L. clariae. Future research topics are highlighted and discussed

The construction of the Katse dam was completed in 1996. The dam started filling in 1995 and reached full capacity in early 1998. It forms part of Phase 1A of the Lesotho Highlands Water Project (LHWP). The main aim of the project is to provide revenue to Lesotho, by transferring water from the catchment of the Senqu (Orange) River in Lesotho to South Africa’s major industrial and population centres. During the implementation of the project, an estimated 130 people were displaced. However, the most serious impact has been the loss of the traditional way of life in the form of arable and grazing land as a consequence of inundation. One of the obligations of the project is to ensure that the standard of living of those affected by the project is not impaired. The Lesotho Highlands Development Authority identified a number of rural development projects, which included fisheries development. This study is an integral part of fisheries development in Lesotho. The aim of this study was to gain an understanding of the biology and the demographics of the fish species in the lake. This information would serve as the basis for the development of a management plan for the sustainable utilisation of the fisheries resources. To achieve this aim, the following specific objectives were addressed: 1. Investigation of the biology of the three principal species. 2. Description of the key population parameters (growth, mortality & recruitment). 3. Investigation of the distribution and relative abundance of the three species. The three principal species in the Katse dam are rainbow trout, Oncorhynchus mykiss, and the two cyprinids, Barbus aeneus and Labeo capensis. Sectioned otoliths were used to age O. mykiss while both otoliths and scales were used to age B. aeneus and L. capensis. Marginal zone analysis revealed that slow growth was experienced in winter for the three species. The maximum-recorded age for both B. aeneus and L. capensis was 12 years while O. mykiss reached 4 years. There was no significant difference in growth rates of the different sexes and growth was best described by the 3 parameter Von-Bertalanfy growth model as Lt = 603[1-e⁻°·¹⁵⁽t ⁺ °·°³⁾] for B. aeneus, Lt = 526[1-e⁻°·²¹⁽t ⁺ °·⁹⁾] for O. mykiss and Lt = 521[1-e⁻°·¹⁷⁽t ⁺ °·²¹⁾] for L.capensis. Male and female O. mykiss attained 50% sexual maturity (Lm₅₀) at 235 and 275mm FL, respectively. There was no difference in Lm₅₀ for male and female B. aeneus and L. capensis. B. aeneus reached sexual maturity at 285mm FL while L. capensis reached sexual maturity at 244mm. Both cyprinid species spawned in summer (November to January) while O. mykiss spawned in winter (May to August). The mean total mortality rate (Z) estimated from catch curves and Butterworth et al (1989) equation was 0.72 yr⁻¹ for B. aeneus, 0.62 yr⁻¹ for L. capensis and 1.32 yr⁻¹ for O. mykiss. The estimate of natural mortality was 0.41 yr⁻¹ for both B. aeneus and L. capensis and 0.81yr⁻¹ for O. mykiss.

An autecological study of the heterosporous fern Azolla filiculoides Lamarck and its endosymbiotic blue-green alga Anabaena azollae Strasburger, based on a combination of field and laboratory studies, is presented. The taxonomy, morphology and anatomy of the fern-alga association were studied as well as nutritional and physiological aspects of the symbiosis. These studies have defined the habitat and nutritional requirements of the fern and have provided new insights into its reproductive biology, nitrogen metabolism and the nature of the association between the fern and alga. In the catchment area of the Hendrik Verwoerd Dam the availability of suitably sheltered habitat limits the distribution of A. filiculoides while the availability of nutrients, in particular calcium, phosphorus and iron, limits the growth of the fern. The multilayered mats formed by A. filiculoides are essential for spore production, cause dramatic changes in the hydrochemistry of the underlying waters and confer a great competitive advantage on the plant. Methods for the isolation of the fern and algal components of the symbiosis have been developed but recombination of the individual organisms to reform the symbiosis was unsuccessful. The development of the fern is closely linked to that of the alga and the association is maintained throughout the life cycle of the fern. Because of its specific habitat and nutritional requirements, A. filiculoides is unlikely to colonize the open waters of the Hendrik Verwoerd Dam.

The concept of cross-border tourism planning and cooperation is investigated in reference to the Lake !Gariep Initiative. The field of cross-border economic planning and integration is an area of increasing interest in regional development studies. The Lake Gariep Initiative is an initiative to promote cross-border planning and development around nature conservation, water resource management, economic development, poverty alleviation and tourism in the three municipalities that surround the Gariep Dam. The Gariep Dam, which is largest dam in South Africa, is surrounded by three provinces. The region is also economically and politically marginalised as it has a small, dispersed population and a marginal contribution to the broader regional economy. Under these circumstances the coordination of resources between municipalities to develop and promote the region has been identified as a key success factor for the region. The Lake Gariep Initiative although strongly supported locally has over ten years failed to be institutionalised. This study examines the Lake Gariep Initiative in terms of the origins of the concept and the key challenges that have been faced in establishing a cross-border, development entity. Findings are based on an assessment of documents on the formation of the LGI, interviews with stakeholders involved in the process and an assessment of critical success factors in reference to national and international case studies. This study provides a review of the key challenges, benefits and critical success factors for cross-border tourism development in relation to the Lake !Gariep Initiative.

M.Sc. (Zoology) / Please refer to full text to view abstract

Master of Science / Department of Computing and Information Sciences / Mitchell L. Neilsen / The United States Department of Agriculture (USDA) is currently researching the effectiveness of various earth dam designs and their ability to prevent erosion. This report utilizes experimental results from the USDA experimental hydraulic engineering research unit to develop computational fluid dynamics models using OpenFOAM. Several variations of smooth and stepped dam models are created and analyzed with OpenFOAM on multiple cores using Message Passing Interface. In this report, seven dam designs are analyzed to extract flow velocities and pressures and animations. This data and OpenFOAM models are helpful for determining potential erosion conditions.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: A flood event in the town of Mariental, in 2006, raised a sudden awareness regarding the state of dam safety in Namibia. Although damage was caused at the town, the flood was not extreme; it was approximately a one in fifty year event. The concern, however, was the increase in risk imposed on the town due to the temporary malfunctioning of the back-up power system: should the secondary back-up system also have failed, the embankment could have overtopped with subsequent failure; a catastrophe. The Rational Quantitative Optimal (RQO) approach, presented in this dissertation, provides a robust risk evaluation model which produces a definitive result for the reduction of risk from the overtopping of earth-fill dams. The model is based on principles of risk, but an assessment of a portfolio of dams provides discrete optimal results, not expressed in terms of probability. All the steps that the methodology comprises have been developed exhaustively and propose to address concerns raised by dam owners and decision makers regarding risk-based dam safety: a transparent framework for decision making related to public safety, which will also appeal to the technically minded portfolio manager looking for a purely quantitative procedure to assist in the decision making process. The RQO process is applied mechanistically, not requiring judgement from the decision maker. It thus addresses the concern raised by dam owners regarding the probability of risk assessment being judgmental. Risk in this dissertation is associated with embankment dams and concomitant external erosion, which globally is the single largest cause of failure of these dams. This specific failure mechanism, in particular, is a threat in Namibia, since other mechanisms, such as internal erosion, poses very little risk to the type of embankment dams typically found in Namibia. Therefore, for practical purposes, the extreme flood hydrology in Namibia is revisited and applied to real dams in the RQO model. Extreme flood hydrology in Namibia has, for the past thirty years, largely been based on the South African Department of Water Affairs Technical Report 137 (TR 137) of 1988; This report proposes an empirically established upper limit of flood peaks, called the Regional Maximum Flood (RMF), which is associated with an annual recurrence interval of 10 000 years, as shown in this study from probabilistic analysis which included palaeoflood data. The updated flood model incorporates thirty years of additional systematic data, as well as palaeoflood data that has resulted from a new approach. The new data have provided an increase in the K‒value boundaries for some of the regional flood zones. A revised graphical distribution of the K‒value zones for Namibia is presented and is proposed as a replacement for the current model. / AFRIKAANSE OPSOMMING: ‘n Vloed in die dorp Mariental, in 2006, het belangstelling in damveiligheid in Namibia aangewakker. Alhoewel skade aangerig is aan die dorp, was dit nie ‘n besonderse groot vloed nie; dit was ‘n vloed met ongeveer ‘n vyftig jaar herhalingsperiode. Kommer met betrekking tot die voorval spruit uit die toename in risiko weens die bystand kragaanleg wat gefaal het toe dit nodig was. Indien die tweede bystand stelsel ook nie gewerk het nie, kon die dam se wal oorstroom het, wat tot katastrofiese faling van die dam kon gelei het. Die Rasionele Kwantitatiewe Optimale benadering (RQO) vir damveiligheid, wat verlaging in risiko teen oorstroming van grondvul damme teweegbring word hier voorgestel. Die model is gebaseer op beginsels van risiko analise, maar die resultaat vir ‘n portefeulje van damme word uitgedruk nie in waarskynlikheidsterme nie, maar in terme van ‘n diskrete optimale antwoord. Die metode is in diepte ontwikkel en spreek onsekerhede aan waarvoor dam-eienaars en besluitnemers te staan gekom het; ‘n deursigtige besluitnemings proses wat die veiligheid van die publiek eerste stel, en wat ook aanklank sal vind by ‘n tegnies georiënteerde bestuurder wat ‘n kwantitatiewe oplossing soek vir besluitneming by ‘n portefeulje van damme. Die RQO proses is meganisties in sy toepassing; dit verg geen oordeel van die besluitnemer nie. Sodoende spreek dit ‘n bekommernis aan wat menige dam-eienaars het oor die onpartydigheid of onbevooroordeeldheid in risiko besluitneming. Risiko word in hierdie studie geassosiëer met grondvul damme en eksterne erosie. Eksterne erosie is op internasionale vlak die grootste enkele oorsaak van faling van grondvuldamme. Hierdie falingsmeganisme is ook die grootste risiko van faling wat in Namibia voorkom, aangesien interne erosie nie by rotsvul damme, wat tipies in Namibia gebou word, ‘n groot risiko inhou nie. Dus, vir die praktiese toepassing van die RQO metode, word die ekstreme vloedhidrologie van Namibië ook onder oënskou geneem. Die afgelope dertig jaar is vloedhidrologie in Namibie hoofsaaklik gebaseer op die streeksmaksimum vloed metode wat deur Kovács (1988), van die destydse Suid Afrikaanse Departement van Waterwese, opgestel is vir lande in suidelike Afrika. Dit is beskryf in die tegniese verslag, die TR 137 van 1988, van die Departement van Waterwese, Suid Afrika. TR 137 stel ‘n streeksverbonde empiries-gebaseerde boonste limiet vir vloede voor, die sogenaamde Streeks Maksimum Vloed (SMV). Hierdie studie het gevind dat die SMV vloede tipies ‘n 10 000 jaar herhalingsperiode het deur ‘n waarskynlikheidsontleding te doen van die vloeirekords en palaeovloeddata. Die opgedateerde SMV vloedmodel vir Namibie sluit in dertig jaar se addisionele aaneenlopend-gemete data, asook nuwe palaeovloed data. Die nuwe data vergroot die areas van sommige van die die K-sones, wat die streeksvloed sones voorstel. ‘n Hersiene kaart met die nuwe K-sone grense daarop aangedui word deur hierdie navorsing aangebied en word voorgestel as ‘n vervanging van die Kovács-SMV-kaart van Namibië van 1988.