A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. May 30, 2016. / In statistics, a model is as good as the data fed to it. Data about hydrological events continues to grow rapidly over the years, with different variables being recorded on a continuous scale. These variables can be interpreted and used in a different manner among disciplines. Thus, choosing the right variables and interactions among variables is an important statistical step in building a good and accurate model. This dissertation involved the development of a statistical model which can be used to predict weekly water level within the Okavango river in northern Namibia. The parameters of the statistical mixed model were estimated based on two methods for longitudinal data, the Generalised Estimating Equations (GEE) which is a well known method of parameter estimation in longitudinal data analysis when the observed variables are correlated, and the Restricted Maximum Likelihood Estimation (REML) which is a likelihood based approach method, unlike the GEE. Using cross-validation and a simulation study, the GEE method of estimation was found to be less accurate and inconsistent in terms of prediction of parameter estimation of water level while the well known REML was found to predict the water level with a good degree of accuracy, consistency and with lower variance. Parameters from a simulation study have also shown less bias in REML method and predicted the cross-validation test-set with less bias. / GR 2016

The Okavango Delta, an internationally recognized wetland, is undergoing natural and anthropogenic change at a variety of spatio-temporal scales. The objective of this research was to utilize remotely sensed imagery to assess the spatio-temporal distribution of flooding and fire and their subsequent influences on vegetation as represented by vegetation index trajectories in the Okavango Delta. The characterization of the spatiotemporal dynamics of vegetation spectral response via a time-series of remotely sensed data not only informs ecosystem and disturbance theory but also presents new methodological applications for multi-temporal change analysis. Disentangling these components from a signal is critical for better assessing the interrelationships among climatic oscillations, disturbance regimes, and human management on ecosystem response. This research tested six hypotheses regarding flooding and fire, and found that the largest number of fires occurred either within 5 km of the border to the Wildlife Management Areas or within the active (flooded a minimum of every two years) floodplains. These hypotheses indicate that burning is highest where people have accessinto the management areas and where the natural resources are plentiful. Periodicities from vegetation signal time-series did not confirm published climate-driven periodicities of 3, 8, and 18-years but did reveal seasonal (6 month) and quasi-decadal periodicities. Vegetation trajectories were more predictable with increasing flood frequency and duration, but were less predictable with increased fire frequency. The fact that increased burning resulted in less predictable behavior indicates the potential of quantifying the anthropogenic influence on the landscape using remotely sensed imagery. Flooding and fire were not statistically correlated to the residual dynamics, refuting the conceptualization of flooding and fire as disturbance and supporting the interpretation of flooding and fire as disturbance regimes. This research thus contributes methodologically and theoretically to the ecology literature by operationalizing tests for disturbance versus disturbance regimes via spatio-temporal characterization. Further, this work extends change detection techniques typically implemented with coarser spatial resolution but more frequently acquired imagery by using harmonic regression and wavelet analysis with Landsat data. Lastly, this work provides a temporally rich assessment of recent vegetation, flooding, and fire trends for improving management efforts of the Okavango Delta.

thesis submitted to the School of Animal, Plant and Environmental Sciences, Faculty of Science, University of the Witwatersrand, Johannesburg in fulfillment of the requirements for the degree of Masters in Science. Johannesburg 2016. / The Okavango Delta in northern Botswana contains the largest, unfenced lion population in southern Africa, and is one of the most important population strongholds for the species on the continent. Despite its conservation importance, however, little information has been published on the drivers of lion ecology in this unique wetland ecosystem. In the Okavango Delta, the annual flood pulse causes dramatic seasonal contractions of available dry land, and consequently variable distribution and abundance of prey. Lions must therefore adapt to a dynamic environment not only on an annual basis, but also on a longer time-scale as inundation patterns cycle from periods of low to high floods. The main aim of the study was to determine which social and ecological factors were most important in determining lion population demographics and social organisation in the unique wetland environment of the Okavango Delta. Data were intensively collected on demographic rates and social organisation of five resident lion prides in the south-western Okavango Delta from 1997 to 2004, during which inundation patterns shifted from low to high floods. We investigated the effects of two ecological factors, namely prey availability and flood extent, and one social factor, namely intra-specific competition, on lion social organisation and population demographics. Lions occurred at high densities, and the population was regulated socially and not by resource limitation. Our results indicated that competition with neighbours exerted the most extensive influence on the lion population and significantly affected the survival of young cubs and reproductive rates. Competition reduced pride size, but contrary to our expectations, also negatively influenced sub-group size, indicating that territorial disputes do not drive sub-group patterns in the Okavango Delta. Prey availability did not appear to be an important limiting factor for the population, and group sizes were inversely related to prey availability, most likely due to habitat saturation resulting in higher levels of recruitment. Prey availability only influenced survival of young cubs, which are most vulnerable to nutritional stress. Higher levels of flooding led to smaller pride and sub-group sizes, indicating that higher flood levels for extended periods may lead to a decline in lion densities due to increased competition for available dry land. While flooding exerted no direct effect on demographic rates, we posit that habitat conversion during high flood cycles causes a decline in prey, resulting in a time-lagged effect on the lion population. Our results show that during low flood cycles when herbivore abundance is high, lions occur at high densities and are largely self-regulated. However, as flood levels increase, prey availability declines and lions are placed under increasing pressure for space and resources, which could ultimately lead to population decline. From a conservation perspective, the south-western Okavango Delta population is thus most vulnerable during periods of high floods, when lion densities naturally decline, and lions may be pushed towards the veterinary fence where human-lion conflict is high. Future studies should focus on how anthropogenic threats around the Okavango Delta threaten the viability of the lion population in this conservation area, and seek to secure important corridors to neighbouring populations. Keywords: lion, Panthera leo, social organisation, pride size, population demographics, survival reproduction, Okavango Delta, flooding, competition, prey abundance / LG2017

No description available.

Amphibians are of great ecological importance and a loss of species will have widespread and dire consequences. Recent population declines and extinctions have resulted in amphibians being labelled the most threatened vertebrate class on a global scale. The unique Okavango ecosystem is well known and documented, yet the amphibians of this region are poorly known. This project aimed at assessing diversity in the Okavango Delta by testing isolation as a possible driver for community composition; determining the effect of hydrology on breeding behaviour; and assessing the status and prevalence of the pathogen Batrachochytrium dendrobatidis (Bd) responsible for the widespread epidemic chytridiomycosis implicated in amphibian decline. Using various monitoring techniques, observations of species occurrence were made at three locations representing different degrees of isolation over a 20 month period. Breeding indicators were observed and frogs were screened for amphibian chytrid fungus. A total of 29 species were recorded, and results indicated that there were no significant differences in community composition between the sampled localities. Species presence, however, was significantly correlated with habitat type. Thus, the availability of suitable habitat appears to be driving amphibian diversity patterns, rather than geographic isolation; and increased habitat diversity near the Delta periphery explains increased amphibian diversity in these areas. Results from breeding indicators suggested that reproduction in continuous breeders was correlated with the annual flood as well as rainfall, whilst that of explosive breeders was correlated with rainfall alone. It is thus proposed that opportunistic breeding behaviour for some amphibian species is driven by the hydrology of the ecosystem; and this may be explained by increased biological production associated with the flood pulse. Outcomes highlight the unique nature of the Okavango Delta system, and emphasises the need for its preservation. A total of 249 swab samples were collected and screened for amphibian chytrid fungus. The geographical distribution of collection samples were evenly spread throughout the localities, and were obtained from at least 25 amphibian species. Analyses proved negative for Bd for the 79.92% swabs analysed thus far and it is concluded that Bd seems absent in the study region, a result which has massive conservation implications for the region. Despite the fact that the Okavango Delta has benefitted from conservation and tourism efforts in the past, the system and its biodiversity remains threatened and effective conservation management strategies must be devised and implemented to ensure its preservation. / Thesis (M.Sc. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Amphibians are of great ecological importance and a loss of species will have widespread and dire consequences. Recent population declines and extinctions have resulted in amphibians being labelled the most threatened vertebrate class on a global scale. The unique Okavango ecosystem is well known and documented, yet the amphibians of this region are poorly known. This project aimed at assessing diversity in the Okavango Delta by testing isolation as a possible driver for community composition; determining the effect of hydrology on breeding behaviour; and assessing the status and prevalence of the pathogen Batrachochytrium dendrobatidis (Bd) responsible for the widespread epidemic chytridiomycosis implicated in amphibian decline. Using various monitoring techniques, observations of species occurrence were made at three locations representing different degrees of isolation over a 20 month period. Breeding indicators were observed and frogs were screened for amphibian chytrid fungus. A total of 29 species were recorded, and results indicated that there were no significant differences in community composition between the sampled localities. Species presence, however, was significantly correlated with habitat type. Thus, the availability of suitable habitat appears to be driving amphibian diversity patterns, rather than geographic isolation; and increased habitat diversity near the Delta periphery explains increased amphibian diversity in these areas. Results from breeding indicators suggested that reproduction in continuous breeders was correlated with the annual flood as well as rainfall, whilst that of explosive breeders was correlated with rainfall alone. It is thus proposed that opportunistic breeding behaviour for some amphibian species is driven by the hydrology of the ecosystem; and this may be explained by increased biological production associated with the flood pulse. Outcomes highlight the unique nature of the Okavango Delta system, and emphasises the need for its preservation. A total of 249 swab samples were collected and screened for amphibian chytrid fungus. The geographical distribution of collection samples were evenly spread throughout the localities, and were obtained from at least 25 amphibian species. Analyses proved negative for Bd for the 79.92% swabs analysed thus far and it is concluded that Bd seems absent in the study region, a result which has massive conservation implications for the region. Despite the fact that the Okavango Delta has benefitted from conservation and tourism efforts in the past, the system and its biodiversity remains threatened and effective conservation management strategies must be devised and implemented to ensure its preservation. / Thesis (M.Sc. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

This thesis presents a first ever extensive analysis of pesticides in water and sediments from the Okavango Delta, Botswana, employing green sample preparation techniques that require small volumes of organic solvents hence generating negligible volumes of organic solvent waste. Pesticides were extracted and pre-concentrated from water by solid phase extraction (SPE) and headspace solid phase microextraction (HS-SPME) while supercritical fluid extraction (SFE) and pressurized fluid extraction (PFE) were employed for sediments. Subsequent analysis was carried out on a gas chromatograph with electron capture detection and analytes were unequivocally confirmed by high resolution mass spectrometric detection. Hexachlorobenzene (HCB), trans-chlordane, 4,4′-DDD and 4,4′-DDE were detected after optimized HS-SPME in several water samples from the lower Delta at concentrations ranging from 2.4 to 61.4 μg L-1 that are much higher than the 0.1 μg L-1 maximum limit of individual organochlorine pesticides in drinking water set by the European Community Directive. The same samples were cleaned with ISOLUTE C18 SPE sorbent with an optimal acetone/n-hexane (1:1 v/v) mixture for the elution of analytes. No pesticides were detected after SPE clean-up and pre-concentration. HCB, aldrin and 4, 4‟-DDT were identified in sediments after SFE at concentration ranges of 1.1 - 30.3, 0.5 – 15.2 and 1.4 – 55.4 μg/g, respectively. There was an increase of pesticides concentrations in the direction of water flow from the Panhandle (point of entry) to the lower delta. DDE, fatty acids and phthalates were detected after PFE with optimized extraction solvent and temperature. The presence of DDT metabolites in the water and sediments from the Okavango Delta confirm historical exposure to the pesticide. However their cumulative concentration increase in the water-flow direction calls for further investigation of point sources for the long-term preservation of the Delta. The green sample preparation techniques and low toxicity solvents employed in this thesis are thus recommended for routine environmental monitoring exercises.

Philosophiae Doctor - PhD / The Okavango Delta is recognized as one of the famous inland wetlands and its sustainable use is important for socio-economic development of Botswana. The Okavango delta comprises permanent swamps, seasonal swamps, and drylands on islands within the delta and the surrounding areas, sustained by Okavango river inflows from upstream and local rainfall. TheOkavango River splits into several distributary channels within the delta. Areas which are flooded annually vary in response to varying inflows into the delta. Peak inflows into the delta occur during the February to May period. Due to the low gradient over the delta, these inflows move slowly resulting in peak outflows from the delta occurring during the June to August period. The inundated area over the entire delta increases from May until it reaches maximum inAugust and starts to decrease from September, reaching minimum inundated area in the months of December and January. The incoming flood wave into the delta and maximum inundation is out of phase with the local rainfall season.Communities living within and around the delta derive their livelihoods from tourism, hunting, fishing, livestock rearing, and crop production. Crop production is carried out on drylands and within floodplains. Some of the households take advantage of the increase in soil moisture arising from this inundation along floodplains to cultivate their crops as the floods recede. This practice is locally referred to as molapo farming which highly depends on inundation of floodplains. The availability of floodplain inundation highly depends on the magnitude of inflows into the delta and the local rainfall which are highly variable resulting in uncertainty regarding successful crop production, availability of livestock grazing areas, and uncertainty in reliance on the wetlands resources such as fishing. The uncertainty experienced in timing of extreme events which cause flooding of resulting in water reaching areas or floodplains where it is not wanted, and also uncertainity in timing of low flows, therefore water not reaching some parts of the delta.Several hydrological studies have been carried out with the aim of improving the understanding of the spatial and temporal dynamics of flows throughout the delta including predicting areas that are likely to be inundated each year. The significant gap addressed by this research is to improve the understanding of the spatial and temporal influence of magnitude and timing of flows on floodplain inundation. Local rainfall on the delta is highly variable over time and space due to its convective nature. This research also addresses the rainfall temporal and spatial variations and its implications on floodplain inundation. The knowledge about spatial extent and duration of floodplain inundation should assist in predicting each year the viability of molapo farming. Three research site, Shorobe, Tubu and Xobe are selected as case studies to understand the dynamics of floodplain inundation induced either by inflows or local rainfall. Local rainfall during the December to March period enables the crops to reach maturity. The onset of the rainy season is very important in supporting sowing of crop seeds. Local rainfall on the delta varies considerably. Aerial rainfall interpolation shows a change in rainfall magnitudes over space in different rainfall months, i.e different parts of the delta receive different rainfall magnitudes in different months of the rainy season. The spatial variation is mainly associated with the migration of the ITCZ southwards first through East Africa during October andNovember and down over Southern Africa in December to February. The movement of the ITCZ brings rainfall concentration on the northern and eastern parts of the Okavango Delta during December to January and bringing rainfall concentration to the northwestern part of the delta around February. However, rainfall spatial correlation between stations can be poor even within the first 150 km therefore implying neighboring places do not experience floodplain inundation by rainfall at the same time. The poor spatial correlation of rainfall between neighboring stations reflects the erratic nature of rainfall in the Okavango Delta characterised by localized thunderstorms. Change detection shows change points in rainfall which can be associated with ENSO episodes. A change point is identified in 1976 and 1977 which can be associated with the El Nino episodes during those years and two change points identified in 1999 and 2004 which can be associated with the La Nina episodes, therefore rainfall induced floodplain inundation can also be associated with wet and dry ENSO episodes. Rainfall does not show any significant trends except for an increasing trend on 10th percentile of Shakawe rainfall. Rainfall also does not show any cyclic behavior. Rainfall over the Okavango Delta can be divided into three unique homogenious sub-regions; sub-region 1: the northern part following the GEV probability distribution and being the region with highest rainfall amounts; sub-region 2: the lower northern and the outlet parts of the Okavango Delta following the GPA distribution with moderate rainfall; and sub-region 3: the middle part of the delta extending to the western and the eastern fringes of the delta, following the P3 distribution and having the lowest rainfall.The main characteristic that defines the Okavango Delta flows at Mohembo is its cyclic behavior. Three significant cycles are identified, close to 10, 20 and 40 years. No significant trends are identified, only a decreasing trend in minimum flows. Change points are identified in 1979 and 1988 and these can be explained by the existing cyclicity since no major land use changes have taken place in the Okavango River Basin upstream before 1989. The existence of cyclicity in Okavango River flows at Mohembo also explains the periodic wetting and drying of different floodplains in the delta. A long period of low flows was experienced from 1983 until 2003 and floodplain inundation extent was greatly reduced, more especially during the 1993-2003. During the 1993-2003 period, flows could no longer reach Maun Bridge along Thamalakne River, therefore leaving molapo floodplains around Boteti River, Gomoti River and Thaoge River to dry out. The 10 and 40 year return floods are important as they indicate the probability of a flood magnitude which has potential to result in major inundation in the Okavango Delta. Therefore, flood magnitudes with recurrence interval 10 and 40 years have high probability of occurring and can cause major floodplain inundation as they can be above the 2009 flood of 969 m3/s, which was the return of major inundation of Okavango Delta floodplains after a long period of dryness. The Ngoqa-Maunachira distributary channel of the Okavango River receives 32% of flow volumes entering the Okavango Delta at Mohembo. 12 % of the Mohembo flow volumes reach the Jao-Boro distributary whilst 1% is received by the Thaoge distributary. Therefore more inundation is experienced along the Ngoqa-Maunachira system compared to the other two. Only about 2% of the Mohembo flow volumes leave the Okavango Delta through Boteti River. Long term shifting of flow direction amongst reaches along the Okavango Delta distributaries is evident more especially along the Ngoqa-Maunachira River system. This results in shifting of inundation. Sub-surface water respond significantly to local rainfall and inflows with high soil moisture conditions retained at 60 cm and 100 cm below the ground.

The study area lies in the central Okavango Delta, Botswana, and was proclaimed a game reserve extension on 2nd July 1976. Peoples of Khoisanoid origin first colonized the area. Bantu speaking baYei followed in about 1750 and baTawana in about 1795. The area is still completely undeveloped and pristine. The solid geology is largely overlain by Kalahari sands, but is seismically very active. Resultant faulting has given rise to the Delta. Further seismic activity, vegetation blockage formation, termitaria establishment and low density of large aquatic moving animals give rise to continual change in water distribution and output at the Delta’s base. These natural factors continually cause dynamic change of flooding regimes. The climate is of summer rainfall and local Delta rainfall is considered a major factor in determining extent and duration of flooding. Five vegetation types divided into 20 plant communities occur. Five communities are dependent on a high water table and 10 on surface flooding for maintenance of specific mammalian habitat types. Floodplain vegetation types are considered most sensitive and ‘normal’ flooding is required to maintain the wetland flora and fauna. Sixty-three mammalian species are recorded from the study area. Twenty-two species are almost wholly dependent on flooding. Lechwe and sitatunga are completely dependent on aquatic and floodplain vegetation types and adequate flooding to conserve their habitat. Water flow in most major channels from ancient to present times has changed radically in distribution. Schemes to extract a more reliable flow out of the Delta for industry and human/stock consumption are laid out and evaluated, and a water demand made for conserved areas. Tourism should be in the form of foot and mekoro or botat safaris. Control of undesirable aquatic vegetation must be monitored. Burning as a management tool is required to enhance flow and control vegetation in some areas. It is premature and unsound to eliminate tsetse fly at this stage. Limited cropping will have to be initiated shortly. Larger tracts of Delta area are required under the direct supervision of the Department of Wildlife and National Parks to maintain the pristine conditions and ensure the conservation of fauna and flora, thereby maintaining the only reason for international tourism to the area. / Dissertation (MSc)--University of Pretoria, 1979. / Centre for Wildlife Management / unrestricted

The central theme of this study revolves around information delivery in a developing community. The notion of appropriate, accessible information networks is scrutinised. The Okavango region in Namibia is used as a case study of a developing, rural community. The region is underdeveloped in important spheres such as health, agriculture and education. Library and related information services are either underdeveloped or undeveloped. The region has a favourable rainfall pattern and a viable agricultural resource base. This is important for Namibia, because the country has large areas of semi-desert and desert. Although the Okavango region is vast ( some 4.6 million hectares), the majority of the population (137,000 at the 1991 census), are settled in a narrow 5-10 kilometre strip along the south bank of the Okavango river. This in itself offers challenging opportunities to improve connectivity and access to appropriate information for community development. The current situation with regard to information delivery and information literacy levels in Namibia is sketched and a detailed description of two projects striving towards appropriate, accessible information delivery given. Both projects are based in a tertiary environment, one at the University of Namibia and the other at five Western Cape tertiary institutions in South Africa. Although, essentially these projects aim at improving information delivery at a tertiary level, community outreach components are woven into the long term vision of both projects. The information literacy components of the projects described are of special significance. The concept of information literacy and the potential of information literacy projects and programmes to facilitate the delivery of appropriate, accessible information to developing communities are probed