Browsing Okavango Research Institute (ORI) by Subject "Botswana"
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Mazvimavi, D.; Mmopelwa, G. (Elsevier, www.elsevier.com/locate/pce, NaN, 2006)[more][less]
Abstract: Lack of access to safe or improved water supply in developing countries is a major global concern, since water is a basic need for sustenance. Programmes aimed at improving access to safe water have been implemented in several sub-Saharan countries. In Botswana, only gazetted settlements have access to water and other basic services provided by the government. This paper examined the level of access to safe water, effort required, and problems encountered in collecting water by households in ungazetted settlements. The paper also investigated whether households in these settlements were willing to pay for improving access to water. The study has been undertaken on settlements located along the Boteti River in the North West District of Botswana. The majority of households in ungazetted settlements satisfy their domestic water requirements through abstracting untreated water from river flows and hand-dug wells when the river is not flowing. Men dominate in collecting water in ungazetted settlements, with the most dominant mode of transporting water being the use of donkey carts. The dominance of men in water collection and use of donkey carts is due to water sources being too distant from homesteads. This has resulted in low water consumption levels, with the per capita water consumption being less than 20 l/capita/ day for most households. Such low levels of water consumption adversely affect attainment of desirable personal hygiene and food preparation. The opportunity cost of time for water collection has been estimated at 1.80 Botswana Pula (P) and the price of water is estimated to be P18/m3 (1.00 P = 0.1755 USD on 18 November 2005). This is higher than the price paid by households residing in rural settlements obtaining water from government or district council water supply schemes. The majority of the households were willing to make a once-off contribution towards improving access to potable water with the mean willingness to pay (WTP) being P161 per household, or just over a third of the statutory agricultural minimum wage in Botswana, P589/month. The potential contribution by household to an improved water supply is significant for a largely unemployed rural population. URI: http://hdl.handle.net/10311/502 Files in this item: 1
Mazvimavi2006WaterAccess.pdf (1.377Mb) -
Swatuk, L.A.; Kgomotso, P.K. (Elsevier, www.elsevier.com/locate/pce, NaN, 2007)[more][less]
Abstract: Supplying adequate water and sanitation facilities to small, scattered rural communities and/or large, fast growing settlements in remote areas is a challenge not easily met anywhere in the world. This article focuses on just such a challenge in the remote, rural area of Ngamiland District in north-western Botswana. Drawing on a combination of critical analysis of government and secondary data, participant observation, and key stakeholder interviews conducted over the period 2004–2006, the article shows that despite a good aggregate record of supplying water and sanitation throughout the country, there are abiding, often serious, problems with supply in remote areas. The research reveals that due to a combination of limited human and financial resource capacity, government policy that deliberately under-serves remote areas in order to encourage resettlement, and complacence among key decision-takers, supply problems go unresolved. The article suggests four key interventions as possible ways forward: using the Okavango Delta Management Plan (ODMP) process as a guiding framework for institutional reform; linking research directly to human resource capacity development; treating water as both a social and an economic good; and soliciting an IWRM ‘champion’ to drive the political process. URI: http://hdl.handle.net/10311/501 Files in this item: 1
Swatuk2007WATERSUPPLY.pdf (1.584Mb) -
Swatuk, L.A.; Motsholapheko, M. (Elsevier, www.elsevier.com/locate/pce, NaN, 2008)[more][less]
Abstract: The Boteti River is an ephemeral outflow of the Okavango River. It lies in the north-western part of Botswana where about 25,000 people reside across a number of widely scattered villages and informal settlements. The river, with its seasonal streams and pans, is vital to the livelihoods of these people, their livestock, and the wildlife that share this physical space. A combination of factors has led to widespread degradation of the physical resource base – both in the river bed itself and in the wider environment. As part of its outreach role, the Harry Oppeheimer Okavango Research Centre has undertaken a multi-year project along the Boteti River to assist people there with the rehabilitation of their resource base. The globally influential concept of integrated water resources management (IWRM) provides the analytical framework, in particular its emphasis on dialogue and stakeholder participation. The project has three primary aspects: facilitation of a dialogue platform; action-research; outreach and information dissemination. After two years of implementation, the project has collected a good deal of data and established a River Basin Forum with a common vision. However, the project continues to face difficulties in implementation: participation is limited; myths regarding resource degradation are difficult to dispel; meaningful communication among differently empowered actors is hard to achieve; and there are numerous human, financial and technological limitations. The primary researchers continue to alter their methods in the hope of achieving a functioning River Basin Committee (RBC), but observe that the globalized ideals of IWRM are, in this particular case at least, of limited use when attempting to alter localized management practices in basins with deeply embedded social and cultural practices. URI: http://hdl.handle.net/10311/504 Files in this item: 1
Motsholapheko2008IntegratedWater.pdf (1.154Mb) -
Sebele, L.S. (Elsevier, www.elsevier.com/locate/tourman, NaN, 2010)[more][less]
Abstract: The impact of Community-Based Natural Resource Management (CBNRM) is seen by many as a ‘win-win’ situation with reference to natural resources conservation and the improvement of local communities’ livelihoods. However, community engagements in CBNRM and tourism have elicited many views as far as natural resources utilization is concerned. Some affirm the importance of CBNRM; others question it, while others call for its improvement. The premise of this study is to investigate the benefits and challenges of community-based tourism in one community of Botswana. Results show that although some benefits have been identified, there remain many challenges for the Khama Rhino Sanctuary Trust (KRST). It is evident that for community-based tourism to bring more benefits for locals, more interaction is needed between them and the Trust management. Increased local involvement and participation will help to ensure that people are empowered and the conservation of natural resources takes place. This paper asserts that community-based ventures, if properly run and managed, can promote the conservation of natural resources and increase local benefits through participation in tourism activities. Description: Case Study URI: http://hdl.handle.net/10311/503 Files in this item: 1
Sebele2010TourismVentures.pdf (1.383Mb) -
Mmopelwa, G.; Ngwenya, B.N. (Academic Journals, December 4, 2010)[more][less]
Abstract: The Okavango Delta is the largest multi-species and multi-gear fishery in Botswana. However, there is lack of an understanding of the nature of fish market in the Delta. The objectives of the survey were (1) to identify and describe the socio economic profile of the fishers in the fishing market, (2) to describe the operations of the market and (3) to identify market constraints of fishing. A structured questionnaire was used to collect data from fishers in four study sites in the Delta. The study revealed that fishing market in the Okavango Delta is very ‘informal’ in nature, with almost no intermediaries, and catering only for the local population. Lack of preservation facilities, transport, low levels of skills and lack of access to credit are the various constraints facing fishers. URI: http://hdl.handle.net/10311/739 Files in this item: 1
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Huntsman-Mapila, P.; Kampunzu, A.B.; Vink, B.; Ringrose, S. (Elsevier; http://www.elsevier.com/wps/find/journaldescription.cws_home/503361/description#description, NaN, 2005)[more][less]
Abstract: [Please note that chemical formulae do not display properly]:The siliciclastic sediments of the Okavango inland Delta of northwest Botswana have a modal composition of quartz arenites and result from a complex history, including transport by river and deposition in a nascent rift basin located in a desert environment with input of aeolian sands. The geochemical composition of sediments from the Okavango Delta was determined in order to constrain the role of weathering at the source and the composition of the source rocks. The chemical analyses and the interelement ratios show a broad compositional range usually encompassing the PAAS composition. The chemical index of alteration (CIA) values and the A-CN-K diagram define an evolution trend which can be interpreted using a mixing model involving a strongly weathered component which corresponds to the sedimentary fraction transported by the Okavango River and a relatively immature component which corresponds to the aeolian sand component of the Okavango sediments. Field geological data supported by geochemical ratios involving elements with affinity for mafic-ultramafic and felsic rocks such as Th/Cr, Th/Sc, La/Sc, La/Co and Eu/Eu* support a source area including mafic-ultramafic and felsic rocks, with or without intermediate rocks. The relationships between certain elements (Cr-Ni, Na2O-Al2O3, K2O- Al2O3) refine the interpretation by pointing to the existence of at least three source rock end-members, including a felsic rock source and pyroxene-rich and olivine-rich mafic-ultramafic source rocks. Proterozoic granitoid-gabbro and related volcanic and ortho-metamorphic rock complexes exposed in NW Botswana and adjacent Angola and Namibia are the source rocks of the sediment component which was mixed with aeolian sand and interacted with a variable proportion of diagenetic carbonates to produce the Okavango sediments. Description: This paper was a contribution to the SAFARI 2000 Research Project. URI: http://hdl.handle.net/10311/153 Files in this item: 2
huntsman_mapila_sedgeo.pdf (6.089Mb)license.txt (1.998Kb) -
Daka, P.S.; Obuseng, V.C.; Torto, N.; Huntsman-Mapila, P. (South African Water Research Commission http://www.wrc.org.za, NaN, 2006)[more][less]
Abstract: Deltamethrin concentrations were determined in 35 sediment samples collected from three different habitats: channel, lagoon and pool sites from Xakanaxa in the Okavango Delta, NW Botswana. The samples were Soxhlet-extracted in acetone to extract deltamethrin residues and subsequently cleaned-up with silica gel 60. The final determination was carried out with a gas chromatograph equipped with an electron capture detector (GC-ECD). The sample work-up and determination gave deltamethrin recoveries of 54 to 97%, and detection limits of 0.004 mg/kg dw. The concentration of deltamethrin residues in the sediment samples collected from the three sprayed areas in the Okavango delta ranged between 0.013 and 0.291 mg/kg dw, with the highest concentrations observed in samples obtained from the pool sites. Analysis of samples for organic matter content showed percentage total organic carbon (% TOC) ranging between 0.19% and 8.21%, with samples collected from the pool having the highest total organic carbon. The concentrations of deltamethrin residues and the % TOC in sediment samples showed a similar trend with the highest levels recorded in the pool samples. These data confirmed that a simple method based on GC-ECD, after Soxhlet extraction, was robust enough to enable quantification of deltamethrin in the sediments, because comparable results were obtained with a more sophisticated system consisting of a GC coupled to a mass spectrometer with a time of flight (TOF) analyser. URI: http://hdl.handle.net/10311/650 Files in this item: 1
Daka_WSA_2006.pdf (1.231Mb) -
Brooks, C.; Bonyongo, C.; Harris, S. (Wildlife Society http://joomla.wildlife.org/index.php?option=com_content&task=view&id=43, NaN, 2008)[more][less]
Abstract: Global Positioning System (GPS) collars are increasingly being used to study fine-scale patterns of animal behavior. Previous studies on GPS collars have tried to determine the causes of location error without attempting to investigate whether the accuracy of fixes provides a correspondingly accurate measure of the animal's natural behavior. When comparing 2 types of GPS collar, we found a significant effect of collar weight and fit on the rate of travel of plains zebra (Equus burchelli antiquorum) females in the Makgadikgadi, Botswana. Although both types of collar were well within accepted norms of collar weight, the slightly heavier collars (0.6% of total body mass [TBM]) reduced rate of travel by >50% when foraging compared with the collar that was 0.4% of TBM. Collar effect was activity specific, particularly interfering with grazing behavior; the effect was less noticeable when zebras crossed larger interpatch distances. We highlight that small differences in collar weight or fit can affect specific behaviors, limiting the extrapolation of fine-scaled GPS data. This has important implications for wildlife biologists, who hitherto have assumed that collars within accepted weight limits have little or no effect on animal movement parameters. URI: http://hdl.handle.net/10311/628 Files in this item: 1
Brooks_JWM_2008.pdf (1.039Mb) -
Mubyana-John, T.; Wutor, V.C.; Yeboah, S.O.; Ringrose, S. (Academic Journals. http://www.academicjournals.org/SRE, NaN, 2007)[more][less]
Abstract: The influence of wild fires on microbial community structure, soil organic matter, sulphur oxidising and nitrifying microbial populations in the floodplains of the Okavango Delta of Botswana was assessed. Microbial community structure was assessed by phospholipids ester-linked fatty acids (PLFA) quantification while microbial sulphur oxidisers were assessed by Most Probable Number (MPN). Community structure assessment showed that burning shifted the microbial community structure from single cellular bacteria being the dominant groups to filamentous fungi and actinomycetes being the most dominant groups. Generally burning increased the fungal component (18:2 w6) matrix from 3.40 to 8.35 while the actinomycetes and sulphur reducing bacterial (10 Me 16:0) component also increased from 1.02 to 1.70 mostly in the floodplains. Generally, the organic matter content declined with burning. However, the influence of burning on soil pH was non conclusive. Soil microbial biomass carbon increased slightly after the fire. The number of heterotrophic and nitrite-oxidizing and sulphur reducing bacteria increased. Overall, these results indicate that burning significantly alters the microbial community structure as large above ground losses of nutrients during and after burning often results in low quantities of nutrients released into the soil. URI: http://hdl.handle.net/10311/349 Files in this item: 1
Fire and.pdf (2.461Mb) -
VanderPost, C.; McFarlane, M. (Elsevier www.elsevier.com/locate/jag, NaN, 2007)[more][less]
Abstract: Locating additional long-term groundwater resources in semi-arid regions of developing countries with growing populations is an expensive undertaking. Simple geographic information system (GIS) techniques can be utilised to facilitate efficient application of expensive geophysical techniques and test-drilling by functioning as an interdisciplinary integration and decision-making tool, especially in data-poor and poorly mapped environments where more sophisticated GIS techniques are not applicable. The paper demonstrates this in the context of the search for groundwater alternatives to the dwindling river water supply in the Boteti area of the Kalahari region in Botswana. URI: http://hdl.handle.net/10311/573 Files in this item: 1
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Ngwenya, B.N.; Kgathi, D.L. (Elsevier Ltd; www.elsevier.com/locate/pce, NaN, 2006)[more][less]
Abstract: This case study investigates access to potable water in HIV/AIDS related home-based care households in five rural communities in Ngamiland, Botswana. Primary data collected from five villages, consisted of two parts. The first survey collected household data on demographic and rural livelihood features and impacts of HIV/AIDS. A total of 129 households were selected using a two-stage stratified random sampling method. In the second survey, a total of 39 family primary and community care givers of continuously ill, bed-ridden or non-bed-ridden HIV/AIDS patients were interviewed. A detailed questionnaire, with closed and open-ended questions, was used to collect household data. In addition to using the questionnaire, data was also collected through participant observation, informal interviews and secondary sources. The study revealed that there are several sources of water for communities in Ngamiland such as off-plot, outdoor (communal) and on-plot outdoor and/or indoor (private) water connections, as well as other sources such as bowsed water, well-points, boreholes and open perennial/ephemeral water from river channels and pans. There was a serious problem unreliable water supply caused by, among other things, the breakdown of diesel-powered water pumps, high frequency of HIV/AIDS related absenteeism, and the failure of timely delivery of diesel fuel. Some villages experienced chronic supply disruptions while others experienced seasonal or occasional water shortages. Strategies for coping with unreliability of water supply included economizing on water, reserve storage, buying water, and collection from river/dug wells or other alternative sources such as rain harvesting tanks in government institutions. The unreliability of water supply resulted in an increase in the use of water of poor quality and other practices of poor hygiene as well as a high opportunity cost of water collection. In such instances, bathing of patients was cut from twice daily to once or not at all. Depending on the severity of HIV/AIDS related symptoms, e.g. diarrhoea, 20-80 additional litres of water could be required daily. The case study demonstrates that, at individual level, access to water is an integral element of the patient's holistic healing process and psychosocial well being. At household and community levels, access to sufficient supplies of potable water when and where it is needed is central to mitigation of HIV/AIDS impacts. Access to water should therefore not be treated strictly as an economic good due to its importance as a basic human need, a social good and indeed a human right. URI: http://hdl.handle.net/10311/172 Files in this item: 2
license.txt (1.998Kb)ngwenya_kgathi_PCE_06.pdf (4.416Mb) -
Ngwenya, B.N.; Mosepele, K. (Elsevier www.elsevier.com/locate/pce, NaN, 2007)[more][less]
Abstract: Generally, rural households pursue all year round natural and non-natural resource-based livelihood systems to diversify these options in order to cope with risks emanating from a range of shocks and stressors. Artisanal fishing in the Delta is not only a major livelihood option but also a source of food security. This paper is based on analysis of primary data collected from a survey of 248 subsistence fishers’ households through simple random sampling in 22 villages in the Delta. The overall objectives of the survey were to assess the general prevalence of HIV/AIDS in the Ngamiland district of Botswana, to investigate potential effects of AIDS-related stressors, particularly chronic illness on artisanal fishing activities, and to assess implications towards food security. Results from this study indicate that HIV prevalence rates for pregnant women attending antenatal clinics in the Delta are approximately 30% and are related to factors such as marriage, education, and employment. Despite this relatively high prevalence percentage, most of the affected households do not have adequate access to HIV/AIDS support facilities. Support services are provided on the basis of population size and/or status of the settlement (i.e. urban, urban village, rural or remote). Therefore, since about 50% of the Delta’s population lives in settlements of less than 500 people, they receive health services indirectly through major population centres whose capacity to deliver timely HIV/AIDS services is limited. This disproportionate access to HIV/AIDS services disadvantages the majority of fishing communities in the Delta, and may affect their ability to fish. Moreover, about 53% of sampled households had cared for a continuously ill person/s (CIP’s) in the last 5 years, out of which approximately 29% felt that this seriously impacted fishing activities. These serious impacts included sale of family assets, depletion of savings, and switching or abandoning fishing activities. Subsequently, household food security is seriously affected because fish provides a significant proportion of food to CIP households where approximately 55% of households get their food from fish products. During food shortages, CIP households resorted to a hierarchy of strategies which included cutting down on meals or reducing meal portions, looking for paid work, gathering wild fruit, asking for food from relatives, selling livestock, and getting social assistance. In conclusion, artisanal fishing is a natural safety net which constitutes an important buffer for households affected by HIV/ AIDS-related stressors in the Okavango Delta. Access to fish helps these households mitigate potentially adverse impacts such as deterioration into chronic poverty. URI: http://hdl.handle.net/10311/572 Files in this item: 1
NGWENYA2007Okavango.pdf (1.602Mb) -
Mubyana, T.; Krah, M.; Totolo, O.; Bonyongo, M. (Journal of Arid Environments. http://www.elsevier.com/wps/find/journaldescription.cws_home/622855/description#description, NaN, 2003)[more][less]
Abstract: The effect of flooding on soil total nitrogen, phosphorus and microbial population in different vegetation zones (floodplain, island and woodland) and profile depth (0?1, 0?5, 2?0, 3?0, 4?0 and 5?0m) of the Okavango Delta was studied from February to July 1999. Total nitrogen significantly differed with soil profile depth, moisture regime and months. In the woodlands, insignificant total nitrogen was detected at all depths except at 0?1m, where 0?03% and 1?17% were detected in February and March, respectively. In the island samples, only 0?05% was detected at 4m in February. Nitrogen in the floodplain samples was concentrated in the A1 horizon where 0?12%, 0?61% and 0?03% were detected in February, March, and May, respectively. Organic phosphorus significantly differed with vegetation zone but not with months and depth. Although organic phosphorus was low (0?02–0?52%) at all sites, it was liberally distributed throughout the profiles. On the island, actinomycetes were only detected up to 2m in February and up to 3m in July. Fungi concentrated in the top 0?5m (103–105). In both the floodplain and island samples, bacteria concentrated in the upper 3m. However, after May, populations decreased significantly. In the floodplain, significant actinomycetes populations were only detected in the upper 0?5m. Generally, organic phosphorus showed positive correlations with fungal populations. This study indicates that these soils are low in total nitrogen and phosphorus. URI: http://hdl.handle.net/10311/293 Files in this item: 1
Influence of seasonal flooding.pdf (3.953Mb) -
Moleele, N.M.; Ringrose, S.; Matheson, W.; Vanderpost, C. (ScienceDirect, www.sciencedirect.com, NaN, 2002)[more][less]
Abstract: the cattle-dominated grazing areas of Botswana. Bush encroachment species – for instance Acacia tortilis, A. erubescens, A. mellifera, Dichrostachys cinerea, Grewia flava, and Terminalia sericea –are increasing in cover and density around foci points (e.g. water points and kraals) at the expense of the grass cover. A number of factors have the effect of encouraging the germination and survival of bush encroachment species. The practice of cattle husbandry and continual shifting of foci points within grazing areas have resulted in the spread of the distribution of bush encroachment species across the country. This is evidenced by the potential extent of 37 000 km2 (6 4% of Botswana) of darkened and near infrared (NIR) reflective bush encroached areas in 1994. This paper suggests that specific management strategies should be adopted to help overcome the bush encroachment problem, which is causing a significant reduction in the extent of Botswana’s high quality rangeland. These strategies may vary from the enforced reduction of grazing intensity in areas identified as being heavily bush encroached to the selective management of opportunistic (communal) grazing in better quality predominantly grassland areas. Further work is however required to update this analysis and especially to consider trends since 1994–1995. While some work on the extent of woody cover and the further causes of bush encroachment is being undertaken under the SAFARI2000 project, more research is needed in specific areas to pinpoint causes and responses to the bush encroachment problem. URI: http://hdl.handle.net/10311/985 Files in this item: 1
Moleele_ et al_More_Woody_2002.pdf (3.119Mb) -
Kgathi, D.L.; Kniveton, D.; Ringrose, S.; Turton, A.R.; Vanderpost, C.; Lundqvist, J.; Seely, M. (Elsevier; www.elsevier.com/locate/jhydrol, NaN, 2006)[more][less]
Abstract: The Okavango basin comprises the Cuito and Cubango active catchment areas in Angola, in addition to the Kavango's Okavango non-active catchment in northern Namibia and Botswana. The Okavango River water and its ecosystem resources are critically important sources of livelihoods for people in the basin. Pressures from livelihoods and development are already impacting on the environment. These pressures may increase in the future due to the rapid increase in population, the peace process and associated resettlement activities in Angola, and major development initiatives in Botswana and Namibia. For instance, possible future increase in water abstraction from the Okavango River may affect the long-term environmental sustainability of the Okavango Delta by minimizing channel shifting and thereby reducing spatial biodiversity. The paper argues that while conservation of the natural environment is critical, the pressing development needs must be recognized. The reduction of poverty within the basin should be addressed in order to alleviate adverse effects on the environment. The paper recommends that the development of sustainable tourism and community-based natural resource management initiatives may be appropriate strategies for reaching the Millennium Development Goals of poverty alleviation and achievement of environmental sustainability in the Okavango Basin. These initiatives have a comparative advantage in this area as demonstrated by the performance of the existing projects. URI: http://hdl.handle.net/10311/154 Files in this item: 2
kgathi_j_hydrology_2006.pdf (6.004Mb)license.txt (1.998Kb) -
Moleele, N.M.; Reed, M.S.; Motoma, L.; Seabe, O. (John Wiley and Sons, http://www.wiley.com, NaN, 2005)[more][less]
Abstract: Laboratory-based seed storage systems have been developed as an alternative to in situ conservation for indigenous woody plant species. However, interactions between seed quality and environmental variables must be known for each species prior to seed collection, storage and sowing to ensure effective conservation. This study investigated Acacia tortilis seed weight/quality patterns across seven Botswana seed provenances in relation to: soil nutrient status, altitude; latitude; slope angle; % grass cover; height and density of other woody plants nearby. The higher rainfall and relatively eutrophic seed provenances of northwestern Botswana (Chobe, Okavango and Makgadikgadi) were associated with large A. tortilis species and seeds, as well as higher densities of woody plants. Spatial variation in seed weights of A. tortilis was principally a function of rainfall and soil organic carbon. Although more work is required to establish the relationship between seed weight and germination rates for A. tortilis, this research suggests that seed collection should focus on sites with high levels of rainfall and soil organic carbon. URI: http://hdl.handle.net/10311/947 Files in this item: 1
Moleele African Jour Eco.pdf (705.1Kb) -
Otter, L.B.; Scholes, R.J.; Dowty, P.; Privette, J.; Caylor, K.; Ringrose, S.; Mukelabai, M.; Frost, P.; Hanan, N.; Totolo, O.; Veenendal, E. (Wageningen Institute for Environment and Climate Research, http://library.wur.nl/, NaN, 2002)[more][less]
Abstract: The Southern African Regional Science Initiative (SAFARI 2000) involved two wet season and one dry season field campaigns. This paper reports on the wet season campaigns. The first was conducted at five sites along the Kalahari Transect in Zambia (Kataba Forest) and Botswana (Pandamatenga, Maun, Okwa River Crossing, Tshane) during February 2000 and concentrated primarily on characterizing the land surface with respect to exchanges of matter and energy with the atmosphere. The second, conducted in February 2001, focused on fluxes of water, gases and energy between the canopy and the atmosphere at Maun, Botswana, and at Skukuza in the Kruger National Park, South Africa. Eddy covariance measurements at Skukuza and Maun were designed to collect a near-continuous record of the seasonality and inter-annual variability in savanna carbon, water and energy exchanges in representative savanna ecosystems. This paper gives brief descriptions of the sites, the measurements made, and the methods used. It highlights some preliminary results, particularly from the first campaign, and outlines the next stages of the SAFARI 2000 project URI: http://hdl.handle.net/10311/1031 Files in this item: 1
Otter_ Southern_africa_2002.pdf (1.002Mb) -
Gieske, A.S.; Wubett, M.T.; Timmermans, W.J.; Parodi, G.N.; Wolski, P.; Arneth, A. (SPIE, http://link.aip.org, NaN, 2004)[more][less]
Abstract: Land surface temperatures are important in global change studies, in estimating radiation budget, heat balance studies and as control for climate models. Several algorithms for estimating land surface temperature and emissivity spectra for multispectral thermal infrared images were developed recently for use with data from the Advanced Spacebome Thermal Emission and Reflection Radiometer (ASTER) on the TERRA platform. Similar methods are also used with the MODIS instrument. In this study, surface temperature and broadband emissivities were determined from the five TIR channels of ASTER instrument in an area on the southern fringe of the Okavango Delta (Botswana). MODTRAN 4 was used to determine the necessary atmospheric corrections while software was developed to facilitate MODTRAN post-processing. The results were compared with micrometeorological observations from a flux tower, with a LANDSAT 7 image of the same day, and finally also with reported ASTER surface temperature and emissivities for the same image (high level ASTER product). Results indicate that the surface temperature depends rather sensitively on atmospheric transmissivity and relatively large temperature differences are found between results from imagery analysis and flux tower. No relation was found between broad-band emissivity and NDVI, contrary to earlier findings in Botswana. URI: http://hdl.handle.net/10311/1015 Files in this item: 1
gieske_procSPIE_2003_pw.pdf (317.2Kb) -
Mitsch, W.J.; Nahlik, A.; Wolski, P.; Bernal, B.; Zhang, L.; Ramberg, L. (Springer, http://www.springer.com, NaN, 2010)[more][less]
Abstract: This paper summarizes the importance of climate on tropical wetlands. Regional hydrology and carbon dynamics in many of these wetlands could shift with dramatic changes in these major carbon storages if the inter-tropical convergence zone (ITCZ) were to change in its annual patterns. The importance of seasonal pulsing hydrology on many tropical wetlands, which can be caused by watershed activities, orographic features, or monsoonal pulses from the ITCZ, is illustrated by both annual and 30-year patterns of hydrology in the Okavango Delta in southern Africa. Current studies on carbon biogeochemistry in Central America are attempting to determine the rates of carbon sequestration in tropical wetlands compared to temperate wetlands and the effects of hydrologic conditions on methane generation in these wetlands. Using the same field and lab techniques, we estimated that a humid tropical wetland in Costa Rica accumulated 255 g C m−2 year−1 in the past 42 years, 80% more than a similar temperate wetland in Ohio that accumulated 142 g C m−2 year−1 over the same period. Methane emissions averaged 1,080 mg-C m−2 day−1 in a seasonally pulsed wetland in western Costa Rica, a rate higher than methane emission rates measured over the same period from humid tropic wetlands in eastern Costa Rica (120–278 mg-C m−2 day−1). Tropical wetlands are often tuned to seasonal pulses of water caused by the seasonal movement of the ITCZ and are the most likely to be have higher fire frequency and changed methane emissions and carbon oxidation if the ITCZ were to change even slightly. Description: Some symbols may not come as they are in the abstract. URI: http://hdl.handle.net/10311/832 Files in this item: 1
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Huntsman-Mapila, P.; Ringrose, S.; Downey, W.S.; Modisi, M.; Coetzee, S.H.; Tiercelin, J-J.; Kampunzu, A.B.; Vanderpost, C. (Elsevier; http://www.elsevier.com/wps/find/journaldescription.cws_home/865/description#description, February 7, 2007)[more][less]
Abstract: [Please note chemical formulae do not display correctly in this abstract]. Sediment samples from a continuous 4.6m profile in the dry bed of Lake Ngami in NW Botswana were analysed for geochemistry and dated using both 14C and TL methods. Certain units in the profile were found to be diatom rich and these, with the geochemical results, were used as indicators of high and low lake levels within the basin. The Lake Ngami sediments contain a high proportion of SiO2 (51-92.5 wt%, avg. 72.4 wt%) and variable levels of Al2O3 (2.04-17.2 wt%, avg. 8.88 wt%). Based on elevated Al2O3 and organic matter (LOIorgc) results, lacustrine conditions occurred at ca. 42 ka until 40 ka and diatom results suggest that relatively deep but brackish conditions prevailed. At 40 ka, the lacustrine sedimentary record was terminated abruptly, possibly by tectonic activity. At ca. 19 ka, shallow, aerobic, turbulent conditions were prevalent, but lake levels were at this time increasing to deeper water conditions up until ca. 17 ka. This period coincides with the Late Glacial Maximum, a period of increased aridity in the central southern Africa region. Generally, increasing Sr/Ca ratios and decreasing LOIorgc and Al2O3, from ca. 16 to 5 ka, suggest decreasing inflow into the basin and declining lake levels. Based on the enrichment of LREE results, slightly alkaline conditions prevailed at ca. 12 ka. Diatom results also support shallow alkaline conditions around this time. These lake conditions were maintained primarily by local rainfall input as the region experienced a warmer, wetter phase between 16 and 11 ka. Lake levels rose rapidly by 4 ka, probably in response to enhanced rainfall in the Angolan catchment. These results indicate that lake levels in the Lake Ngami basin are responding to rainfall changes in the Angolan catchment area and local rainfall. The results confirm that the present-day anti-phase rainfall relationship between southern Africa and regions of equatorial Africa was extant during the late Quaternary over the Angolan highlands and NW Botswana. URI: http://hdl.handle.net/10311/152 Files in this item: 2
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