Literatura académica sobre el tema "Range management – Botswana – Okavango River Delta"

Aquatic ecosystems in Botswana have been under threat by the aquatic alien invasive plant species viz., salvinia Salvinia molesta Mitchell, water lettuce Pistia stratiotes L., and water hyacinth Eichhornia crassipes (Mart.) Solms-Laub. While salvinia has been termed the major threat to the Botswana wetlands, water lettuce and water hyacinth are considered to be of minor importance. This review presents the species biology, distribution, historical spread, negative impacts, control achieved right from their discovery in the country by referring to their control and management in the world. Having infested the Kwando-Linyanti-Chobe Rivers in the 1970s, salvinia was initially tried by the use of herbicides, paraquat and glyphosate, between 1972 and 1976. With the discovery of the host specific biological control weevil Cyrtobagous salviniae Calder and Sands in 1981, the weevil was introduced by Namibians on Kwando and Chobe Rivers in 1983 and by Botswana in 1986 in the Okavango Delta. While the control was slowly establishing in Kwando-Linyanti-Chobe Rivers, it became apparent that lakes and perennial swamps within and outside Moremi Game Reserve of the Okavango Delta were infested with salvinia from 1992 onwards. With continuous and sustained liberation of the weevil in the Kwando-Linyanti-Chobe Rivers and in the Okavango Delta between 1999 and 2000, salvinia control was achieved by 2003, and since then the weevil constantly keeps the weed at low levels. The success is mainly due to sustainable monitoring through the application of physical and biological control methods. However, salvinia is still threatening the Okavango Delta due to factors such as tourism activities, boat navigation fishing and transporttion by wild animals. The first occurrence of water lettuce was recorded on Kwando and Chobe Rivers in 1986. Its biocontrol weevil Neohydronomous affinis Hustache was released in the year 1987. The weevil became extinct in Selinda Canal and Zibadianja Lake on Kwando River due to dry and wet events for over 10 years and the weed had been under control biologically on Chobe River. Having surface covered the Selinda and a part of the Zibadianja in high flood and rainfall in 1999/2000 season, research was undertaken to contain water lettuce, which led to its eradication by 2005. Regular physical removal of the water lettuce prior to fruit maturity is an effective method of control or eradicating the weed in seasonal water bodies. The Limpopo Basin (shared by Botswana, South Africa, Zimbabwe and Mozambique) has become vulnerable to water hyacinth infestation. Water hyacinth infested the trans-boundary Limpopo River in 2010 sourced from Hartbeesport Dam on Crocodile River in South Africa. Botswana and South Africa have been consulting each other to implement integrated control of the weed jointly in the Limpopo River. Water hyacinth could be a continuous threat to the dams and the rivers in the Limpopo basin if its control is not taken seriously. These three species are found growing in Botswana in a range of pH between 4.5 and 10.3 and in the range of conductivities between 20 and 580 µS cm-1. Range of soluble nitrates, phosphates and potassium in the habitats of salvinia infestations were 0.02 to 1.5, 0.01 to 1.78 and 0.3 to 6.92 mg L-1 respectively. Water lettuce infestation in the seasonal Selinda Canal had a maximum of 4.7 mg L-1 nitrates, 2.8 mg L-1 phosphates and 7.9 mg L-1 potassium. Nevertheless, these three nutrients were in the range of 0.41 to 9.56 mg L-1, 0.2 to 2.9 mg L-1, and 7.7 to 11.53 mg L-1 respectively in the Limpopo River where water hyacinth infestations were observed. These nutrients were considerably high during decomposition phase of biological control of weeds. The Government of Botswana “regulates the movement and importation of boats and aquatic apparatus, to prevent the importation and spread of aquatic weeds both within and from the neighboring countries” by “Aquatic Weed (Control) Act” implemented in 1986. These measures, combined with communities, conservation groups, NGOs and public awareness campaigns, have highlighted the gravity of aquatic weeds spreading into wetlands, dams and other water bodies. In conclusion, the Government of Botswana is committed and supportive through the Department of Water Affairs in protecting the wetlands of the country efficiently and prudently.

Managing any inland fishery requires reliable age data and accurate estimates of growth rate. Clarias gariepinus, the largest catfish species in most tropical African floodplain river systems, is an important constituent of subsistence fishery catches. We used otolith-derived age estimates to describe patterns of age and growth for C. gariepinus from the Lower Okavango Delta in northern Botswana. Edge analysis of sectioned sagittal otoliths showed that growth zone deposition occurred during the annual flood peak between July and September. The maximum recorded age was 8 years. Growth was best described by the von Bertalanffy Growth Model of the form E[L|age] = 528.70(1–e–0.72(age+1.35)). A comparison of growth parameters from this study with those from previous studies suggests two distinct populations of C. gariepinus between the Upper and Lower Okavango Delta, emphasising the importance of regional stock assessment for key fishery species. The fairly short life span and high variability in growth of C. gariepinus are important indicators that it is imperative to maintain natural habitat and flow regime for sustainable management of fishery resources in the Lower Okavango Delta.

Desiccation of river channels, resulting from low inflows, is among the major shocks affecting household livelihoods in the Okavango Delta, Botswana. Household coping and adaptive strategies against this shock are believed to be inadequate owing to changes in policy, land use and environmental conditions. This paper aims to improve knowledge on household capacity to adapt to desiccation in the Okavango Delta. It identifies and assesses the impacts of desiccation on rural livelihoods, the household strategies, and the impacts of institutional changes on household responses. Informed by the sustainable livelihood and socio-ecological frameworks, the study used a survey of 526 households and other qualitative methods. The results show that desiccation adversely affected livelihood activities. Household responses included livestock relocation to wetter areas, livelihood diversification, digging of wells and boreholes, and switching from flood recession to rain-fed cultivation. Land use and institutional changes inhibited household adaptation to desiccation. Additionally, households did not sufficiently use opportunities resulting from desiccation. The study concludes that the ability to capitalise on opportunities created by climatic shocks needs to be developed at all levels, as this can improve adaptation to the impacts of, and reduce losses from, future climate variability and change in Botswana and other developing countries.

The evolution of tourism destinations is influenced by a range of factors including the policy and planning framework, the role of destination management organisations, and integration of tourism into the local and national economy. The aim of this paper is to describe how the private sector can influence destination development, by considering a luxury safari lodge (Mombo Camp) and its holding company (Okavango Wilderness Safaris) within the Okavango Delta of Botswana. Through a series of stakeholder interviews and literature review, the research found that Mombo had influenced the destination’s quality standards, how it is marketed and promoted, and also in the conservation of endangered species. Over the course of 30 years, the holding company has also been influential in the development and implementation of tourism and conservation policy, environmental awareness among youth, and also conservation research. The findings of this study suggest that destination planning authorities should encourage reputable private sector operators that have a long-term interest in the destination and promote sustainable tourism practices, including those that can mobilise a network of facilities and attractions, can collaborate with their competitors, and can support and advise government on policy and its implementation.

AbstractWe examined the seasonal and inter-annual variation of leaf-level photosynthetic characteristics of three C4 perennial species, Cyperus articulatus, Panicum repens and Imperata cylindrica, and their response to environmental variables, to determine comparative physiological responses of plants representing particular microhabitats within a seasonal tropical floodplain in the Okavango River Delta, Botswana. Five measurement campaigns were carried out over a period of 2 y which covered two early rainy seasons, two late rainy seasons and one dry season. For all three species, light-saturated net photosynthetic rates (Asat) and stomatal conductance (gsat) decreased with decreasing soil water content with a seasonal range for Asat of approximately 5–45 μmol m−2 s−1, and for gsat of 0.03–0.35 mol m−2 s−1. The species representing the wettest microhabitat (Cyperus) had the highest gsat at low leaf-to-air vapour pressure deficits (Dl), the highest ratio of intercellular to ambient CO2 concentration (Ci/Ca), as well as the highest degree of variation in Ci/Ca from season to season. We interpret this as being indicative of its adaptation to a moist growth environment allowing for non-conservative water use strategies as soil moisture is usually abundant. For all three species there was significant variation in photosynthetic fluxes from one year to another that was related to variation in leaf nitrogen and phosphorus. This study shows that when assessing the role of savanna stands in large-scale carbon balance models, the remarkable inter-annual variation in leaf photosynthesis reported in this study should be taken into account.

<p>Since a spectrum of hydrological and geomorphological conditions produce flood pulse environment in a riverine or a deltaic system, it is essential to have the knowledge on spatial and temporal distributions of river flow and dependent processes for environmental flow requirements, ecosystem maintenance, water resources management, and hydrological forecasting among others. Such systems being complex as the exchange of flows between the main channel and the flood plains are not well understood, flow partitioning dynamics between the various channels on large water bodies are often difficult to represent even with sophisticated models. In view of this, an attempt has been made to apply a short-term stochastic forecasting model-an Auto Regressive Integrated Moving Average (ARIMA) aided by Artificial Neural Networks (ANNs) to partition flows into the downstream tributaries, viz.: Lopis and Gadikwe channels from the Khiandiandavhu-Maunachira (K-M) Junction Junction (the main river channel) river system of the iconic Okavango delta in Botswana. As such, observed monthly flow data between October 2005 and September 2008 at the K-M Junction, and the two downstream tributaries were used to test the performance of these hybrid models for the complex deltaic system. It was found that the partitioned flows at Lopis and Gadikwe agree very well with observations when using a Single Input Multiple Output (SIMO) ANN (i.e. an inverse variant of the widely used Multi Input Single Output (MISO) ANN architecture) and an ARIMA (1,1,1) model. The Mean Squared Errors (MSEs) in the forecasts were also minimal, thus giving some hope on the use of such a hybrid mode for the rest of the branched river networks of the whole Okavango delta.</p>

The Okavango is a vast inland delta system in northern Botswana which receives an annual flood from the highlands of southern Angola. There are distinct communities of fish in the Okavango which can be separated from each other by the physical characteristics of the different habitat types with which they co-evolved. This thesis provides an account of the biology and ecology of selected fish species in the Okavango Delta. Their response to the annual flood regime, and the environmental factors which limit their distribution and abundance, are examined. The thesis emphasizes the importance of water fluctuations in determining the nature of the fish fauna and the reaction of the fishes in terms of community structure, movements, breeding, predator-prey interactions and feeding. Four major ecotones were studied in the Okavango Delta. In the riverine floodplain and perennial swamp ecotones a higher species diversity was recorded than in the seasonal swamp and drainage rivers ecotones where diversity was lowest and comprised mainly of smaller fish species. A greater variety of habitat types was associated with the riverine floodplain and perennial swamp relative to the seasonal swamp and drainage rivers. The variety of habitat types between ecotones is associated with the degree of flood inundation in the respective ecotones. During the course of this study, annual recruitment of fish into the drainage rivers was from refugia in the seasonal swamp whereas the greatest degree of lateral and longitudinal movement was in the riverine floodplain and perennial swamp. Movement was in response to both biological requirements, such as availability of food and spawning sites, and physical features of the environment, such as the changing water depth. The total catch per unit effort (CPUE) of fish throughout the year was more constant in the riverine floodplain and perennial swamp than in the seasonal swamp and drainage rivers where CPUE fluctutated widely. An increase in CPUE during the duration of this study was apparent and related to the magnitude of the annual flood. In contrast to most other African wetlands, the arrival of the annual flood in the Okavango Delta coincides largely with the dry winter months. This situation presented an opportunity to compare the influence of floods and water temperature on the reproductive biology of the selected fish species. The results show a definite pattern and indicate that both the flood cycle and increased water temperatures greatly influence the breeding cycles of the selected species. The tilapia Oreochromis andersonii exhibited a considerable degree of phenotypic plasticity. Fish from the seasonally inundated areas showed a smaller mean size, egg size and larger number of eggs relative to fish in the perennially flooded areas. The size at sexual maturity was also smaller. These different reproductive characteristics exhibited by O. andersonii are dependent on the degree of water retention in the different habitats. The fishes of the Okavango have adopted other reproductive strategies to survive the changing environmental conditions brought about by an annual flood cycle. These strategies include the construction of foam nests, as described for Hepsetus odoe, for guarding the young and to provide an oxygen-rich environment. Two main non-piscivorous feeding pathways were identified in the Okavango. These are a detritus pathway based on dead plant and animal material, and an epiphyte pathway, based on algae and invertebrates that are attached to plant stems. Seasonal changes in diet in relation to the annual flood were recorded. The most dramrtic change was demonstrated by the catfish Clarias gariepinus which congregates in mass aggregations in the northern regions of the Delta and hunt in packs. Pack-hunting by catfish is a regular response to the annual fluctuations in water level. It is my conclusion that the main flow of biotic and abiotic stimuli within the Okavango Delta originates from the relatively hydrologically stable riverine floodplain and perennial swamp ecotones to the widely fluctuating seasonal swamp and drainage rivers ecotones. The relatively stable ecotones allow a diverse and biotically interdependent fish community to develop, whereas the widely fluctuating seasonal swamp and drainage rivers ecotones are characterized by a less diverse and interdependent fish community. The degree of abiotic and biotic interdependence among fish in an ecotone is very important for the long term management of the Okavango Delta. Potential developers have to determine whether the effect of a given action by man is likely to result in a long term disturbance or merely in an elastic recoil to a more or less similar state. Recommendations are made on the conservation and management of Okavango fishes taking into account the ecological characteristics of the delta.

Thesis (MA (Political Science. International Studies))--University of Stellenbosch, 2010.
Bibliography
ENGLISH ABSTRACT: Water is life. Its availability and quality directly relates to what is possible in agriculture as well as human health. In Southern Africa, water issues have become an important political agenda as a result of the droughts that the region has been experiencing. The Southern Africa Development Community (SADC), in its water protocol advises its member states to set up river basin organisations to manage transboundary rivers in Southern Africa. The aim is to encourage the sustainable use of international rivers. Sharing international rivers has proven to be a very difficult issue as shown by the voting patterns on the UN Convention on the Law of Non Navigational Uses of Transboundary Rivers and the subsequent failure of entry into force of this convention. While strategic interests on the global levels manifest themselves in voting patterns in forums like the UN Assembly, the situation is trickier at the regional level. These strategic interests are ever present as a result of states’ need for recognition of their sovereignty and the inability of states to accept any hierarchical enforcement. This study investigates the impact of these interests at the basin level on the structure of cooperation. With the use of a case study, namely the Okavango River Basin Commission, and guided by regime theory, the study looks at the process of regime formation and maintenance in the basin. It concludes that states use cooperative arrangements (international water cooperation regimes) as tools for the strategic protection of their sovereignty.
AFRIKAANSE OPSOMMING: Water is lewe. Die beskikbaarheid en kwaliteit het direk te betrekking op wat moontlik toeneemed is in landbou so wel as menslike gesondheid. Water as ʼn noodsaaklike bron in suider-Afrika word meer en meer beskou as ʼn belangrike kwessie op die politieke agenda as gevolg van droogte wat in die streek ondervind word. ʼn Hoë vlak van belangrikheid word aan die bestuur van water binne die streek geheg. Die SAOG (Die Suider – Afrikaanse Ontwikkelings gemeenskap), het in sy water protokol aan sy lid state beveel om rivier kom organisasies te stig om beheer uit te oefen oor riviere in Suider- Afrika wat oor grense heen vloei. Die doel is om lidstate aan te moedig om die volhoubare gebruik van internasionale riviere te bevorder . Die vedeling van internasionale riviere is ‘n komplekse kwessie soos wat VN stempatrone aandui ten opsigte van die Wet op die Verbod teen Navigasie op Oorgrensende Riviere en die daaropvolgende versuim van die inwerkingtreding van die Konvensie aandui. As gevolg van state se behoefte vir erkenning van hul soewereiniteit en hul strategiese belange bly die deel van rivierkomme ‘n moeilike internasionale probleem. Hierdie studie ondersoek die impak van die bogenoemde belange op die kom vlak op die struktuur van samewerking. Met die gebruik van ʼn gevallestudie, naamlik die Okovango Rivier Kom Kommissie, en aan die hand van regime teorie, ondersoek die studie die proses van regime formasie asook die problematiek rondom die instandhouding van die Komissie. Die gevolgtrekking is dat state koöperatiewe reëlings (internasionale water samewerking regimes) as instrumente vir die beskerming van hul strategiese soewereiniteit en eie belange gebruik.

The Okavango Delta is an extremely dynamic system with variable vegetation comprised of permanent swamps, seasonal swamps, dry islands, floodplains and dry grassland, savanna and woodland. The system is largely driven by the interaction between fire and the annual flood, which filters down from the Okavango River catchments in Angola. While extensive research has been conducted on the flood-driven vegetation little is known about the dry woodland and savanna regions bordering these flood-driven habitats. A taxonomic classification of woody species composition resulted in eleven vegetation types. These data were then reanalyzed in terms of woody species morphology allowing these eleven vegetation types to be grouped into four functional response groups in order to provide a platform for improving the understanding of how dry woodland and savannas interact with the environment. These four groups were the savanna group mixed thornveld and the three woodland groups; mixed broadleaf woodland, shrub mopane woodland and tall mopane woodland. Burning in mixed thornveld and mixed broadleaf woodland was found to decrease woody species density and grass fuel loads and could be used for grazing management to remove unpalatable growth and improve grass species composition, while burning in shrub mopane woodland and mixed mopane woodland merely decreased the woody understory and is not recommended. Utilization dominated by grazing livestock resulted in overutilization of the grass sward leading to bush encroachment in both mixed thornveld and shrub mopane woodland, while utilization by goats alone resulted in underutilization of the grass sward and a dominance of herbaceous annuals. Livestock utilization had no effect on the occurrence of Pecheul-loeschea leubnitziae, a shrubby pioneer previously thought to be an indicator of overgrazing, however extensive P. leubnitziae cover was associated with a sward dominated by shade-tolerant grasses with low forage quality. Shrub mopane woodland and tall mopane woodland appear to be more stable vegetation states than mixed broadleaf woodland and mixed thornveld being less vulnerable to colonization by pioneer species and alteration as a result of utilization or environmental factors. For this reason management and monitoring of mixed thornveld and mixed broadleaf woodland is essential to prevent vegetation degradation and to ensure optimal forage availability for both livestock and wildlife.
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

This dissertation reviews the principles of International River Basin Management and their application by the governments of Angola, Botswana and Namibia. The dissertation deals with the issues popularised by governments, water planners and international agencies that the twenty-first century's conflicts will be fought over water. Increasingly this concern is being used to justify new water-supply dams and river diversion projects. This is especially so in arid Southern Africa, the focus of this dissertation, where numerous major international water transfers are underway and many more are being planned. While Namibia's growing thirst is a serious problem, the story is more complicated than just too many basin states putting their straws into one glass. The growing conflicts over the Okavango's water use raise broader questions about ownership of common resources, and equity of access to those resources. Most southern African countries depend on primary natural resources to sustain economies and their people. The environmental issues are remarkably similar in countries within the region, and the economic, social and political fortunes of the individual countries are intertwined. Furthermore, the ways in which resources are being managed are similar and thus cause for common concern. In general, the ability of countries in the region to achieve sustainable development depends not on national policies but also on the commitment of neighbours to practice sound environmental management. This is because activities in one country can easily cause impacts on a neighbour and possibly result in "downstream" opportunity costs. This case study of the Okavango River Basin, a river facing prospective developments from riparian states Angola, Botswana and Namibia, attempts to find sustainable solutions to solving international resource conflict. In addition to outlining the possible future threats to the Okavango River, this study proclaims a number of recommendations in the way of declaring alternatives to Namibia's plans to extract water from the Okavango River. One such recommendation is the encouragement of Water Demand Management as an alternative to water transfer by Namibia. This management strategy is aimed at optimising the use of available water rather than developing new or extended supplies and as a result it has a vital role to play since it contributes to sustainable development rather than over exploitation of limited natural resources. The majority of large rivers in the Southern African Development Community (SADC) are shared by three or more countries, and as the region's water resources come under growing development pressure, the importance of establishing effective national and regional methods and institutions for sustainably managing these resources will increase greatly. From economic, ecological and human welfare perspectives, the Okav,ango River Basin is arguably one of the most important transboundary natural resources (TBNR) in the region. Owing to the basin's remoteness and history of conflict, the Okavango was spared much of the destructive developments that rivers in the region have suffered. As a result, the relatively pristine Okavango ecosystem continues to provide significant benefits to the region much as it has done for centuries. As we approach the new millennium, however, it is clear that the health of the Okavango River Basin is threatened as riparian states increasingly turn to the Okavango to support their growing populations and economies.
Thesis (M.Env.Dev.)-University of Natal, Pietermaritzburg, 2002.

This chapter examines how the availability and non-availability of river flows has affected benefits realized by communities residing along the Boteti River in Botswana. The Boteti River, which is about 350 km long, derives all its flows from outflows of the Okavango Delta and then discharges into the Makgadikgadi Pans. Peak outflows from the delta occur during the dry season, June to October, and during wet years such as from 1974 to 1982, water flows along the whole river from the delta to the Makgadikgadi Pans. Since 1991, outflows from the delta have only covered about 50 km, with the rest of the river being dry. There has been lack of flows on the downstream section in some years (e.g., 1929-39, 1941-47). Communities residing along the 50 km stretch that is annually flooded benefit from the river through livestock watering, flood recession crop cultivation, fishing, and harvesting of aquatic plants for food and construction. These benefits were not realized by those residing along the rest of the 300 km stretch that was not receiving flows from the delta during the 1991-2008 period.