Research Articles (Earth Sciences)

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Definitions matter: Including the socio-economic dimension as a critical component of SADC circular economy definitions
(Academy of Science of South Africa, 2022) Grobler, Lizette; Schenck, Catherina; Blaauw, Derick
Globally, scholars agree that there is a lack of clarity on the notion of the circular economy (CE) and a lack of consensus on a foundational definition of the term. Some definitions place greater emphasis on the socio-economic dimension of the CE than others. In Africa, notions of the CE are still evolving. This paper highlights the salient aspects of texts defining or informing the CE in the Southern African Development Community (SADC). In Africa, the transition to circularity is motivated by the need to stimulate job creation and income generation. At the same time, concern over mounting environmental impacts is increasing. Economic and population growth on the continent, continued urbanisation, and the resulting proliferation of municipal waste contribute to these economic, social and environmental challenges.
Editor’s message: Building capacity and partnerships towards sustainable utilization of groundwater in Africa
(Springer, 2008) Xu, Yongxin
This Editor’s Message advises the international groundwater fraternity of new opportunities in hydrogeological developments in Africa. It is a fact that groundwater plays a vital role in socio-economic and ecological services in the continent but it has been largely neglected in the past. With the 6th Ordinary Session of AMCOW (African Ministers’ Council on Water) held in Brazzaville, Congo in late May 2007, the profile of groundwater in the continent has been raised.
Factors influencing the awareness and adoption of borehole-garden permaculture in Malawi: Lessons for the promotion of sustainable practices
(MPDI, 2021) Hinton, Rebekah G. K.; Macleod, Christopher J. A.; Wanangwa, Gift
Using wastewater accumulating around rural waterpoints to irrigate community gardens, borehole-garden permaculture (BGP) presents a method of sustainable water management. BGP also presents public health benefits through the removal of stagnant water around boreholes, key Malaria breeding grounds, and through providing year-round food to supplement diets. By analysing a dataset of over 100,000 cases, this research examines the awareness and adoption of BGP across Malawi. Generalised linear models identified significant variables influencing BGP awareness and uptake revealing that socioeconomic, biophysical and waterpoint-specific variables influenced both the awareness and adoption of BGP. BGP had low uptake in Malawi with only 2.4% of communities surveyed practising BGP while 43.0% of communities were aware of BGP. Communities in areas with unreliable rainfall and high malaria susceptibility had low BGP awareness despite BGP being particularly beneficial to these communities.
Foreword to special section: groundwater in Africa
(Wiley-Blackwell, 2010) Bradbury, Kenneth R.; Xu, Yongxin
Influence of termites on the soil seed bank in an African savannah
(Wiley, 2018) Masocha, Mhosisi; Dube, Timothy
In savannah ecosystems, termites drive key ecosystem processes, such as primary production through creation of patchiness in soil nutrients availability around their nests. In this study, we evaluated the role of termites in altering the soil seed bank size, an important ecosystem component that has often been overlooked in previous work. Data on above ground vegetation and soil seed bank samples were collected from four microhabitats, that is, the wooded mound, unwooded mound, tree sub‐ canopy and the open grassland matrix in a protected game reserve in south‐central Zimbabwe. The seedling emergence method was then used to identify species present in the soil samples. One‐way analysis of variance followed by Tukey's multiple comparison tests was executed to test for significant differences in plant species richness among the four microhabitats. The results indicate that plant species richness was high on wooded termite mound but did not differ between the unwooded and the sub‐canopy microhabitats.
The role of ground water in Sub-Saharan Africa
(Wiley-Blackwell, 2010) Braune, Eberhard; Xu, Yongxin
Although water resources managers speak of a water crisis in Africa, the management of ground water has to date not featured strongly in national and regional African water agendas. Examination of the physical environment of the continent and, in particular, the water resources in relation to the socioeconomic landscape and regional development challenges makes it clear that widely occurring, albeit largely low-yielding, ground water resources will be crucial in the achievement of water security and development. Ground water is important primarily in domestic water and sanitation services, but also for other local productive needs like community gardens, stock watering, and brick-making, all essential to secure a basic livelihood and thus to alleviate poverty. Despite the importance of small-scale farming in Africa, there is little information on the present and potential role of ground water in agriculture. In contrast to its socioeconomic and ecological importance, ground water has remained a poorly understood and managed resource. Widespread contamination of ground water resources is occurring, and the important environmental services of ground water are neglected. There appear to be critical shortcomings in the organizational framework and the building of institutional capacity for ground water. Addressing this challenge will require a much clearer understanding and articulation of ground water’s role and contribution to national and regional development objectives and an integrated management framework, with topdown facilitation of local actions.
A synthesis of past, current and future research for protection and management of papyrus (Cyperus papyrus L.) wetlands in Africa
(Springer Verlag, 2014) van Dam, A. A.; Kipkemboi, J.; Mazvimavi, Dominic; Irvine, K.
Papyrus wetlands (dominated by the giant sedge Cyperus papyrus L.) occur throughout eastern, central and southern Africa and are important for biodiversity, for water quality and quantity regulation and for the livelihoods of millions of people. To draw attention to the importance of papyrus wetlands, a special session entitled ‘‘The ecology of livelihoods in papyrus wetlands’’ was organized at the 9th INTECOL Wetlands Conference in Orlando, Florida in June 2012. Papers from the session, combined with additional contributions, were collected in a special issue of Wetlands Ecology and Management. The current paper reviews ecological and hydrological characteristics of papyrus wetlands, summarizes their ecosystem services and sustainable use, provides an overview of papyrus research to date, and looks at policy development for papyrus wetlands. Based on this review, the paper provides a synthesis of research and policy priorities for papyrus wetlands and introduces the contributions in the special issue. Main conclusions are that (1) there is a need for better estimates of the area covered by papyrus wetlands. Limited evidence suggests that the loss of papyrus wetlands is rapid in some areas; (2) there is a need for a better understanding and modelling of the regulating services of papyrus wetlands to support trade-off analysis and improve economic valuation; (3) research on papyrus wetlands should include assessment of all ecosystem services (provisioning, regulating, habitat, cultural) so that trade-offs can be determined as the basis for sustainable management strategies (‘wise use’); (4) more research on the governance, institutional and socio-economic aspects of papyrus wetlands is needed to assist African governments in dealing with the challenges of conserving wetlands in the face of growing food security needs and climate change. The papers in the special issue address a number of these issues.
A two-step approach for detecting Striga in a complex agroecological system using Sentinel-2 data
(Elsevier, 2021) Mudereri, B.T; Abdel-Rahman, Elfatih Mohamed; Dube, T
Information on weed occurrence within croplands is vital but is often unavailable to support weeding practices and improve cropland productivity assessments. To date, few studies have been conducted to estimate and map weed abundances within agroecological systems from spaceborne images over wide-area landscapes, particularly for the genus Striga. Therefore, this study attempts to increase the detection capacity of Striga at subpixel size using spaceborne high-resolution imagery. In this study, a two-step classification approach was used to detect Striga (Striga hermonthica) weed occurrence within croplands in Rongo, Kenya. Firstly, multidate and multiyear Sentinel-2 (S2) data (2017 to 2018) were utilized to map cropland and non-cropland areas using the random forest algorithm within the Google Earth Engine. The non-cropland class was thereafter masked out from a single date S2 image of the 13th of December 2017. The remaining cropland area was then used in a subpixel multiple endmember spectral mixture analysis (MESMA) to detect Striga occurrence and infestation using endmembers (EMs) obtained from the in-situ hyperspectral data. The gathered in-situ hyperspectral data were resampled to the spectral waveband configurations of S2 and three representative EMs were inferred, namely: (1) Striga, (2) crop and other weeds, and (3) soil. Overall classification accuracies of 88% and 78% for the pixel-based cropland mapping and subpixel Striga detection were achieved, respectively.

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