Northeastern South Africa Research Articles

A method for estimating maximum safe installable power for groundwater extraction with application to Africa

New groundwater development is a likely way to meet growing global water demand but needs careful management. To help inform the sustainable development of groundwater resources, a novel method based on the maximum safe installable power for water pumping systems and the maximum safe remaining installable power (considering current abstraction) is developed. The proposed model couples energy, technology and hydrogeological parameters, and is then developed to compute the maximum power that can be safely installed per km2 without exceeding a maximum annual pumpable volume, calculated through available recharge and storage. The model is applied to estimate the maximum safe installable power across Africa with a 0.2-degree resolution, using available energy and hydrogeological data. Constrained by recharge (considering that 25 % of the annual recharge is available for utilization), the maximum safe installable power ranges between 0 and 9960 W/km2 across Africa with regions such as the Congo Basin (~340 W/km2), and western Africa between the Ivory Coast and Nigeria (~230 W/km2) identified as having high potential for sustainable pumping system development. Constrained by storage (considering that 0.1 % of storage can be withdrawn per year), it ranges between 0 and 13,425 W/km2 highlighting the ability to harness storage for pumping system development in the large aquifers of Northern Sahara (~8720 W/km2). When considering limitations posed by both groundwater recharge and aquifer storage (considering that 25 % of the annual recharge and 0.1 % of storage can be withdrawn per year), along with current groundwater withdrawal, 93 % of the maximum safe installable power remains still installable on average across Africa. Nevertheless, 2 % of the locations are estimated to be already experiencing overexploitation, particularly in Sudan, northern Africa, and northeastern South Africa. These findings provide a novel and adaptable way to examine water security, which can assist institutions in targeting investments to meet water demand sustainably.

Phylogeographic structuring in a widespread southern African grass snake (Psammophiinae: Psammophylax rhombeatus)

ABSTRACT The structural and environmental heterogeneity within southern Africa has given rise to many morphological forms of Psammophylax rhombeatus distributed throughout the country, with previous studies neglecting the associated molecular significance of these forms. The species’ widespread, generalist ecology coupled with the substantial phylogenetic structuring previously acknowledged within the species, makes P. rhombeatus the ideal candidate for phylogeographic analyses. Using 103 samples, representing the full distribution of the species, phylogenetic analyses retrieved four well-supported clades: south-eastern South Africa, south-western South Africa, north-eastern South Africa and western South Africa. Although not variable enough to warrant taxonomic re-evaluation, the clades are phylogenetically distinguishable, with relatively high intraspecific genetic divergence values separating them, irrespective of the small geographic distances separating populations. This is likely a product of the taxon’s habitat-generalist lifestyle, enabling them to bypass vicariant barriers that might otherwise cause speciation in less versatile species. The clades are also geographically distinct, with little overlap, indicating previous vicariance, a finding that is supported by the split of P. rhombeatus from P. ocellatus in the mid-Pliocene, followed by the diversification of P. rhombeatus into four clades throughout the Pleistocene. The genetic structuring observed in P. rhombeatus may be a product of population expansion following ancient refugial isolation (potentially Last Glacial Maximum). The morphological groupings highlighted in previous studies are loosely attributable to the molecular clades identified in the phylogenetic reconstruction, highlighting the complex interplay of genetic and morphological characteristics in the process of speciation, and their representation in systematic accounts.

Immunologic, virologic and drug resistance outcomes in an HIV-infected prospective cohort on treatment in South Africa.

In September 2016, South Africa introduced the Universal Test and Treat (UTT) programme to manage HIV infection. However, the development of drug resistance and sustaining viral suppression are challenges to the success of treatment programmes. This prospective observational study describes virologic, immunologic, and drug resistance profiles in a test and treat cohort in north-eastern South Africa. Five hundred and thirty-four HIV-1 positive antiretroviral naïve adults entering treatment programmes were enrolled between January 2016 and February 2018. Trends in CD4+ cell count, viral load, and drug resistance by examination of deep sequences were assessed at baseline and every three months, for 24 months. Seventy-five percent were late initiators into ART (that is baseline CD4+ cell counts < 500 cells/microliter) and 16% were early initiators into ART and baseline CD4 was not available for 9%. Eleven percent (12/104) achieved immunological response after 6 months, 39.4% (41 /104) after 12 months, and 97.5% (101/104) after 24 months. Seventy-one percent (381/534) had baseline viral loads >1000 RNA copies/ml. Nine percent (22/246) achieved viral suppression after 3 months, 50% (122/246) after 6 months and 73.6% (181/246) after 12 months. A slower viral suppression was observed for males than females (p value = 0.012). A total of 45.6% (52/114) individuals had at least one drug resistance mutation (DRM) detected at >20% threshold in any of the time points, and the number increased to 55% (63/114) when minor variants were accounted for. Forty-eight percent (14/29) had drug resistance mutations at >5% threshold as early as 3 months into treatment. The UNAIDS target of 95% viral suppression in individuals under treatment was not observed after 12 months of treatment, and this was less successful for males. Adherence and drug resistance monitoring could be beneficial for individuals harbouring resistant viruses early into treatment.

Estimating crop coefficients and water use of a full-bearing mango orchard in north-eastern South Africa using the fraction of vegetation cover and a dual source evapotranspiration model

In semi-arid countries like South Africa, commercially produced mango (Mangifera Indica L.) are grown entirely under irrigation. However, there is little accurate quantitative information on the water use of mango orchards, and few accurate water use models currently exist. In this study, we evaluated the performance of the FAO 56 method of estimating crop evapotranspiration (ETc) and a dual source water use model against measurements of actual consumptive water use of a commercial mango orchard. The FAO approach calculates ETc as the product of a crop coefficient (Kc) and the reference evapotranspiration (ETo). We derived Kc for well-watered orchards from readily available data including the fraction of vegetation cover, average tree height, and a stomatal control coefficient. The dual-source model calculated orchard evapotranspiration as the sum of tree transpiration and orchard floor evaporation derived from the modified Shuttleworth and Wallace model. Actual evapotranspiration was measured using an open path eddy covariance system, while tree transpiration was measured using the heat ratio method of monitoring sap flow. Data were collected in a mature ‘Tommy Atkins’ mango orchard grown with micro-sprinkler irrigation in north-eastern South Africa. Results show that the reference evapotranspiration explained most of the variation in orchard transpiration (R2 ∼ 0.78) compared to the solar radiation (R2 ∼ 0.66) and the vapour pressure deficit of the air (R2 ∼ 0.66). Compared with field measured water use data, the FAO method gave relatively accurate estimates of transpiration (R2 = 0.74, NRMSE = ±18.00 %, NMAE = ±15.00 %, NSE = 0.70) and evapotranspiration (R2 = 0.58, NRMSE = ±19.00 %, NMAE = ±16.00 %, NSE = 0.55). NSE is the Nash-Sutcliffe Efficiency. The dual-source model yielded slightly less accurate estimates of transpiration (R2 = 0.61, NRMSE = ±22.00 %, NMAE = ±20.00 %, NSE = 0.39) and evapotranspiration (R2 = 0.52, NRMSE = ±23.00 %, NMAE = ±25.00 %, NSE = 0.51). The basal crop coefficient (Kcb) showed small seasonal fluctuations, varying between 0.40 and 0.60 throughout the year. In contrast, Kc showed clear seasonality varying between 0.59–0.64 at flowering and fruit set and rising to 0.81–0.90 during the fruit growing phase. Estimates of the annual total transpiration (686 mm) from the FAO method were within 5 % of the actual measured values (677 mm) while the dual source model estimated 612 mm of transpiration, which was almost 10 % lower than the measured values. The results highlight that even though the FAO method requires fewer input parameters, it is potentially more accurate in estimating water use in mango orchards than the dual-source model.

Distribution, abundance, population structures, and potential impacts of the invasive snail, Tarebia granifera in aquatic ecosystems of north-eastern South Africa.

Aquatic ecosystems globally have been invaded by molluscs. Tarebia granifera is a highly successful invader, often becoming the dominant aquatic invertebrate species in an invaded ecosystem. Resultingly, it has been suggested that T. granifera may have severe negative impacts on these invaded ecosystems. Limited information is available regarding the population structures and densities of T. granifera, particularly in invaded countries such as South Africa, and information on this could assist in developing management and control strategies for this invasive species. The present study aimed to assess the current distribution, densities, and population structures of T. granifera in invaded habitats on the Limpopo and Phongolo River systems in South Africa. This was accomplished by collecting aquatic molluscs from sites across these systems. Water quality parameters were measured at each site and water samples were collected for chemical nutrient analyses. The density of snails was determined for each site and the population size and structure as well as birth rate was calculated for T. granifera. Tarebia granifera was found to be the dominant molluscan species in habitats where it was present and all size classes from newborn to mature adults were found throughout at some of the highest densities globally. Worryingly, native molluscan species, were often absent or in much lower densities than reported in literature at sites where T. granifera was present, suggesting a negative effect on the native molluscan density and diversity. Contrary to most previous studies, there were no significant correlations between T. granifera and the selected water quality parameters. Higher densities and newborn recruitment of T. granifera were observed in the spring than in autumn, likely in response to shifts in environmental conditions. This study provides crucial insights into the population structure, densities, and impacts of T. granifera in invaded habitats, particularly for relatively newly invaded regions such as southern Africa.

Kalanchoe deliae (K. [subg. Kalanchoe] sect. Raveta; Crassulaceae subfam. Kalanchooideae), a new species from the Barberton Centre of Endemism in northeastern southern Africa

A new species, Kalanchoe deliae (Crassulaceae subfam. Kalanchooideae), is described from northeastern South Africa. As far as is known, this new species is restricted to central-east Mpumalanga, one of the eastern-most provinces of the country. Kalanchoe deliae fits in K. sect. Raveta, a cluster of species with small to medium-sized to very large, paddle- to soup plate-sized leaves, and dense, elongated, usually club-shaped inflorescences. Kalanchoe deliae can be easily distinguished from K. luciae, the best-known representative of K. sect. Raveta and with which it occurs sympatrically, by a combination of vegetative (smaller overall stature and smaller leaves; lack of often intensely red-infused leaves) and reproductive (sepal shape and length; corolla lobe colour, shape, and orientation; pistil shape; and size and shape of the nectar scales) morphological characters.

Two new species of Stylochaeton (Araceae: Aroideae) from South Africa

We are describing here Stylochaeton glaucophyllum and S. sekhukhuniense, two new species from northeastern South Africa. Both species have a restricted distribution and are endemic to the Sekhukhuneland Centre of Plant Endemism, Limpopo and Mpumalanga Provinces, South Africa. The new species occur sympatrically with S. natalense, but never with one another. Stylochaeton glaucophyllum prefers norite and pyroxenite hills and mountains, whereas S. sekhukhuniense is associated with similar rock types in low-lying rocky areas. Both new species have the base of the spadix and infructescence partly below-ground and are mainly associated with open savannah. Stylochaeton glaucophyllum can be distinguished from S. sekhukhuniense in having greenish blue leaves with linear lobes while S. sekhukhuniense has green leaves with elliptic lobes. The leaves of S. glaucophyllum are longer (112–332 mm) than those of S. sekhukhuniense (44–180 mm). The petiolar sheath of S. sekhukhuniense extends into two slender, curling ligulae which are absent in S. glaucophyllum. Also included here is a key to the seven currently accepted species of Stylochaeton in southern Africa (South Africa, Eswatini, Zimbabwe and Mozambique).

A 900-Year Isotopic Proxy Rainfall Record from Northeastern Botswana

A high-resolution climate archive was reconstructed based on carbon isotope analysis and radiocarbon dating of the Chapman baobab in northeastern Botswana. The Chapman baobab, which exhibited an open ring-shaped structure composed of six stems, collapsed in January 2016 during an intense El Niño event. Two samples belonging to the oldest stems were investigated in order to obtain a proxy rainfall record, which provides insight into the precipitation regime over the last millennium, evincing centennial and decadal scale variability. The results indicate that the Medieval Warm Period was marked by relatively stable precipitation, whereas rainfall variability and drought frequency increased during the Little Ice Age. The investigated area has experienced both wetter and drier conditions in the past. The wettest conditions of the last millennium were registered before 1450 while the driest period occurred in 1835. For southern Africa, inter-annual rainfall variability is mainly associated with sea surface temperatures in the Agulhas Current core region, which determine the east–west displacement of tropical temperate troughs. Previous studies suggested that positive sea surface temperature anomalies in the Mozambique Channel led to an eastward movement of the troughs but the Chapman record demonstrates a westward displacement in the past, causing drought in northeastern South Africa and wetter conditions in the central part of southern Africa. The positive rainfall correlation with SST anomalies reversed after 1900, causing a gradual decrease in precipitation and confirming the current aridity trend for Botswana. The results contribute to a better understanding of the past climate of southern Africa for which paleoclimate reconstructions remain scarce.

Modern pollen- and phytolith-vegetation relationships at a wetland in northeastern South Africa

In palaeoenvironmental reconstructions, few studies have focused on comparing the presence of pollen and phytoliths in surface sediments to the local vegetation. Notwithstanding inherent differential pollen and phytolith preservation, production, and dispersal, which affect their recovery and interpretation in sediment archives, there remains a need to explore modern pollen-vegetation, phytolith-vegetation and pollen-phytolith relationships to improve palaeoenvironmental reconstructions. We carried out palynological and phytolith analysis on six surface sediment samples linked to the botanical survey of five vegetation survey plots at Gustav Klingbiel Nature Reserve, Mpumalanga province in northeastern South Africa, to understand the relationships between the modern pollen and phytolith assemblages in the surface sediments and the contemporary vegetation of the study area. Correspondence Analysis (CA) was undertaken to examine the fingerprint of the local vegetation in the modern pollen-phytolith assemblage and evaluate whether the phytolith and pollen assemblages were tracking each other. CA illustrated that pollen and phytolith proxies are not tracking the same primary vegetation signals; modern pollen assemblages best represent the components of forest and wetland vegetation. In contrast, modern phytolith assemblages best represent grassland vegetation. Our study shows that differential pollen and phytolith preservation, production and dispersal significantly affect sediment records more than anticipated, thus combining multi-proxies (e.g., phytoliths, pollen) provides a more accurate basis for the interpretation of fossil spectra in palaeoenvironmental reconstructions.

Perceived Effectiveness of Agricultural Cooperatives by Smallholder Farmers: Evidence from a Micro-Level Survey in North-Eastern South Africa

The importance of agricultural cooperatives and other community-based organizations in facilitating sustainable agricultural development in South Africa cannot be downplayed. The aim of the study was to analyse smallholder farmers’ perception of the effectiveness of agricultural cooperatives in rendering support services to their enterprise in Mpumalanga Province of South Africa. A multistage sampling procedure was employed to elicit data from a sample of 120 smallholder farmers drawn from 150 farmers—members who were currently active members of agricultural cooperatives. A structured questionnaire was used to collect data that were analysed using descriptive statistics. Multiple linear regression was used to determine the socio-economic and institutional factors influencing the member farmers’ perception of cooperative effectiveness. The findings revealed that although agricultural cooperatives in the area rendered some level of support services to their members, the majority of the respondents perceived their cooperative as ineffective in rendering some key support services to them that could potentially improve their livelihoods. The results of inferential analysis indicate that factors such as farm size, level of education, household size, farming experience, major crop grown/animal reared, number of cooperative members, support services received index, and satisfaction of leadership processes were significant socioeconomic and institutional factors that influence respondent’s perception. The study recommended increased government public recognition and support for agricultural cooperatives development, increased resource base through more access to grant and donations, and improved linkages between cooperatives and extension agencies as a means of improving the effectiveness of agricultural cooperatives in the area.

Human infrastructure, surface water and tree cover are important drivers of bird diversity across a savanna protected area-mosaic landscape

ContextProtected areas are important in mitigating threats to biodiversity, including land conversion. Some of the largest protected areas are located in biodiverse savanna systems where a mosaic of land-uses exist beyond their borders. The protected areas located in such systems are often host to threatened species and diverse animal communities. In spite of the ecosystem services birds provide, we do not know how functionally and evolutionary diverse the community is in north-eastern South Africa, or what the drivers of such diversity are inside and outside one of the world’s largest savanna protected areas: Kruger National Park (KNP).ObjectivesFirstly, we aimed to investigate how bird species richness, functional richness, phylogenetic and beta diversity (including its components), and rarity differed across the KNP protected area and its adjacent mosaic. Secondly, we aimed to investigate the habitats and proximity to the KNP boundary that drove patterns across three biodiversity metrics. We also investigated whether differences in sample sizes of the citizen science data we employed, impacted results in a significant manner.MethodsTo investigate our aims, we used bird species records from the Southern African Bird Atlas Project 2 (a citizen science project that collects data at a 5 min latitude by 5 min longitude resolution), and for elucidating drivers of community composition, we used a finer scale remotely sensed product.ResultsHuman infrastructure, water sources and tree cover were overall the most significant and strongest drivers of bird diversity in the region; however, the patterns were complex. Specifically, we found that species richness was strongly and positively influenced by seasonal water and infrastructure mostly inside the protected area (KNP). Most significantly and somewhat concerning, though, were the strong negative effects that infrastructure had on bird functional and phylogenetic diversity inside KNP and, to a lesser extent, inside the mosaic. Seasonal water had a similarly strong but positive effect on species richness in the protected area, a random sub-sample of the former and the mosaic. Tree cover also had a negative and significant effect across the region on phylogenetic diversity and was the strongest driver of this diversity metric.ConclusionsOur results displayed the significant but negative influence that relatively little infrastructure had on bird functional- and phylogenetic diversity inside the KNP protected area despite its positive effect on species richness. Water sources across the protected area-mosaic landscapes also significantly affected regional savanna bird community richness. An increase in tree cover negatively affected phylogenetic diversity inside and outside the protected area as well as the mosaic: a similar finding to other studies in South African savanna systems. We showed the importance of habitat heterogeneity, specifically its components such as infrastructure, freshwater systems and tree cover, and how these impact independently and differently on bird communities across a large biogeographical savanna region.

Epidemiology of chronic multimorbidity and temporary migration in a rural South African community in health transition: A cross-sectional population-based analysis.

In sub-Saharan African settings, the increasing non-communicable disease mortality is linked to migration, which disproportionately exposes sub-populations to risk factors for co-occurring HIV and NCDs. We examined the prevalence, patterns, and factors associated with two or more concurrent diagnoses of chronic diseases (i.e., multimorbidity) among temporary within-country migrants. Employing a cross-sectional design, our study sample comprised 2144 residents and non-residents 18-40 years interviewed and with measured biomarkers in 2018 in Wave 1 of the Migrant Health Follow-up Study (MHFUS), drawn from the Agincourt Health and Demographic Surveillance System (AHDSS) in rural north-eastern South Africa. We used modified Poisson regression models to estimate the association between migration status and prevalent chronic multimorbidity conditional on age, sex, education, and healthcare utilisation. Overall, 301 participants (14%; 95% CI 12.6-15.6), median age 31 years had chronic multimorbidity. Multimorbidity was more prevalent among non-migrants (14.6%; 95% CI 12.8-16.4) compared to migrants (12.8%; 95% CI 10.3-15.7). Non-migrants also had the greatest burden of dual-overlapping chronic morbidities, such as HIV-obesity 5.7%. Multimorbidity was 2.6 times as prevalent (PR 2.65. 95% CI 2.07-3.39) among women compared to men. Among migrants, men, and individuals with secondary or tertiary education manifested lower prevalence of two or more conditions. In a rural community with colliding epidemics, we found low but significant multimorbidity driven by a trio of conditions: HIV, hypertension, and obesity. Understanding the multimorbidity burden associated with early adulthood exposures, including potential protective factors (i.e., migration coupled with education), is a critical first step towards improving secondary and tertiary prevention for chronic disease among highly mobile marginalised sub-populations.

Correlates of smallholder poultry farmers extension and marketing information needs: Evidence from north-eastern South Africa

This study investigated the extension and marketing information needs of poultry farmers in Nkomazi, South Africa. A structured questionnaire was used to collect data through face-to-face interviews from 91 randomly sampled smallholder poultry farmers in the area. Descriptive statistics and Pearson Product Moment Correlation (PPMC) analysis was used to analyse the correlates of the extension and marketing information needs of the poultry farmers. The results revealed that information on optimal production, disease management, feeding and water management are prominent areas where information and advisory services were highly needed by the farmers. Also, areas of high marketing information need by the poultry farmers were on product promotion and advertisement, record keeping and market outlet and strategies. Farmer's income, membership of farmer groups, and access to extension visits were significant correlates of the farmers extension and marketing information needs. The study recommended a need to improve on the implementation of the National Extension Policy by extension organisations through scaling-up their level of reach to poultry farmers in the area and ensure that the prominent areas of extension and marketing information needs highlighted are focused on when rendering extension and advisory services to the farmers.

Drivers of scarcity in the globally threatened Taita Falcon Falco fasciinucha: competition and habitat quality in the eastern escarpment region of South Africa

Summary The Taita Falcon Falco fasciinucha is known to occur and breed at only a few locations in eastern and southern Africa and is currently listed as globally “Vulnerable” and “Critically Endangered” in South Africa. An accurate estimation of its conservation status is however hampered by a lack of data and understanding of the species’ habitat requirements and competitive interactions with congeners. Our aim was to address some of these knowledge gaps. We conducted cliff-nesting raptor surveys across a substantial area of the Mpumalanga/Limpopo escarpment in north-eastern South Africa and modelled habitat suitability for nesting Taita Falcons in relation to the proximity of conspecifics and a community of five other sympatric cliff-nesting raptor species, and in relation to a suite of biotic and abiotic environmental variables. Results suggested the location of Taita Falcon nest sites was negatively associated with distance to the nearest pair of conspecifics and the nearest pair of Lanner Falcons Falco biarmicus, and positively associated with tracts of intact, unfragmented forest and woodland around the base of the cliffs. Our results indicated that Taita Falcon and Lanner Falcon appeared to be responding in opposite ways to a directional change in environmental conditions. This response appeared to be detrimental to Taita Falcon and beneficial to Lanner Falcon. Furthermore, the degradation and destruction of Afrotropical woodland and forest is a documented and ongoing reality, both locally and across much of the Taita Falcon’s global distribution. We argue that our findings are sufficient to justify uplisting Taita Falcon to globally “Endangered”.

Natural Vegetation Edges Promote Bat Activity in Macadamia Orchards in Northeastern South Africa

Agricultural intensification can result in extremely fragmented landscapes with typically only small natural areas remaining. The South African macadamia industry is expanding dramatically, with over 5000 ha planted per year. Remaining natural vegetation around macadamia orchards will be key to retain important ecosystem services such as biological pest control of insects provided by, amongst others, insectivorous bats. We evaluated how the activity of bat species on macadamia farms within different land-use mosaics is related to general insect abundance and what role the phenological stages of macadamias play. Recordings of bat echolocation and insect light trap collections were conducted (July 2019 – March 2020) at different edges of land-use types on two macadamia farms in Hazyview, South Africa. Results showed that edge type significantly influenced bat activity and insect abundance with natural vegetation edges recording the highest bat activity (n = 3153) and insect abundance (n = 16 524). River edges (bat n = 1635, insect n = 11 284) presented lower activity and abundance than natural edges but still double that of road edges (bat n = 695, insect n = 3743). Bat activity was also higher during developing-nut and mature phenology stages when pest insects peak. Bats from all foraging guilds were recorded during the study, which points towards a more intact bat assemblage within the study area compared to other macadamia areas in South Africa. Our study highlights the importance of retaining natural vegetation within an agricultural land-use mosaic to maintain biological pest control.

On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change

AbstractRidging South Atlantic Anticyclones contribute an important amount of precipitation over South Africa. Here, we use a global coupled climate model and the ERA5 reanalysis to separate for the first time ridging highs (RHs) based on whether they occur together with Rossby wave breaking (RWB) or not. We show that the former type of RHs are associated with more precipitation than the latter type. The mean sea level pressure anomalies caused by the two types of RHs are characterized by distinct patterns, leading to differences in the flow of moisture‐laden air onto land. We additionally find that RWB mediates the effect of climate change on RHs during the twenty‐first century. Consequently, RHs occurring without RWB exhibit little change, while those occurring with RWB contribute more precipitation over the southern and less precipitation over the northeastern South Africa in the future.

Using cloud computing techniques to monitor long-term variations in ecohydrological dynamics of small seasonally-flooded wetlands in semi-arid South Africa

• Semi-arid Southern African wetlands are lost due to unsustainable use and poor management. • Ramsar Convention on wetlands encourages development of frameworks for wetlands conservation. • The implementation of these frameworks is hindered by a dearth of high-resolution data. • Google Earth Engine (GEE) offers opportunities to address data challenges. • Findings underscores the relevance of GEE in evaluating wetland ecohydrological dynamics. Wetlands in drylands have high inter- and intra-annual ecohydrological variations that are driven to a great extent by climate variability and anthropogenic influences. The Ramsar Convention on Wetlands encourages the development of frameworks for national action and international cooperation for ensuring conservation and wise use of wetlands and their resources at local, national and regional scales. However, the implementation of these frameworks remains a challenge. This is mainly due to limited availability of high-resolution data and suitable big data processing techniques for assessing and monitoring wetland ecohydrological dynamics at large spatial scales, particularly in the sub-Saharan African region. The availability of cloud computing platforms such as Google Earth Engine (GEE) offers unique big data handling and processing opportunities to address some of these challenges. In this study, we applied the GEE cloud computing platform to monitor the long-term ecohydrological dynamics of a seasonally flooded part of the Nylsvley floodplain wetland complex in north-eastern South Africa over a 20-year period (2000–2020). The specific objectives of the study were 1) to evaluate wetland ecohydrological dynamics using the 20-year multi-date Landsat composite data coupled with the Random Forest machine learning algorithm, and 2) to establish the major drivers of wetland ecohydrological changes, using selected spectral indices (i.e. Normalised Difference Vegetation Index (NDVI), Normalised Difference Water Index (NDWI) and Normalised Difference Phenology Index (NDPI)) coupled with climate data. The ecohydrology of the wetland changed over time, with some classes increasing twice when compared to the previous measurement, while others decreasing significantly during the study period. Notably, the bare surface class increased at rates of 230% and 350% between 2006–2010 and 2016–2020, respectively. Moreover, the indices showed similar trends throughout the 20-year period, with NDWI having minimum values less than zero in all cases. This implied no surface inundation, although the presence of some wetland vegetation indicated seasonal to semi-permanent soil saturation conditions. A comparative analysis of climate data and remotely sensed indices showed that annual changes of precipitation and evapotranspiration were the main drivers of wetland ecohydrological variations. The findings of the study underscore the relevance of cloud computing artificial intelligence techniques, and particularly the GEE platform, in evaluating wetland ecohydrological dynamics for semi-arid southern African systems which are deteriorating due to the unsustainable use and poor management resulting from limited knowledge about their changes over time.

Analyses of groundwater storage change using GRACE satellite data in the Usutu-Mhlatuze drainage region, north-eastern South Africa

Study regionThe Usutu-Mhlatuze Water Management Area located in northern KwaZulu-Natal province, South Africa. Study focusRecent studies have indicated a steady decline in groundwater levels in the Usutu-Mhlatuze Water Management Area. However, the absence of representative aquifer storage parameter values including storativity and specific yield, lack of sufficient groundwater monitoring wells and inconsistent and erratic groundwater level observation data from existing limited networks make it difficult to understand groundwater storage changes in the region. Therefore, this study analyses groundwater storage change of the primary and secondary aquifers within the Usutu-Mhlatuze Water Management Area using GRACE satellite derived terrestrial water storage data, Global Land Data Assimilation System (GLDAS) soil moisture data and in-situ measured surface water storage information. New hydrological insights for the regionThe GRACE derived groundwater storage anomalies for the Usutu-Mhlatuze Water Management Area showed good agreement with in-situ groundwater storage anomalies observed from the limited groundwater level monitoring piezometers in the primary and secondary aquifers. The goodness of fit (R2) between the GRACE derived and the observed groundwater storage changes in the primary and secondary aquifers were 0.79 and 0.74, respectively. The GRACE derived groundwater storage change data for the entire study period (between 2002 and 2020) indicated that the primary and secondary aquifers experienced a groundwater storage loss of 925 × 106 m3 and 3614 × 106 m3, respectively.

An ethogram for the nesting and breeding behaviour of the Hooded Vulture Necrosyrtes monachus

Most vulture species worldwide are in decline and of conservation concern. Despite the growing attention to vultures, relatively few studies have focused on their breeding behaviour. Understanding all aspects of a species’ behaviour and its behavioural needs could help to inform conservation efforts. Behavioural studies can be enhanced with the use of an ethogram that clearly defines and describes distinct behaviours. We present the first ethogram detailing the nesting and breeding behaviours of the Critically Endangered Hooded Vulture Necrosyrtes monachus, compiled from over 400 000 nest camera photographs and from hours of direct personal observations at nests in north-eastern South Africa. We describe 28 behaviours that Hooded Vultures exhibited in and around their nests, and these fell into five discrete categories: Movement, Resting, Body Care, Social, and Nesting. We also present 34 camera trap images depicting behaviours from within each category, and discuss the uses and limitations of behaviour-recording technologies. Many of these behavioural elements may be common across vulture species, and so this ethogram may be a useful starting point for other researchers studying vultures globally.

Using a Large Climate Ensemble to Assess the Frequency and Intensity of Future Extreme Climate Events in Southern Africa

This paper uses 7,200 smoothed climate change projections for each of the four emissions scenarios, together with inter-annual variation provided by detrended historical climate data to investigate changes in growing season (wettest 3 months) weather patterns from the 2020s to the 2060s for ten countries of Southern Africa. The analysis is done in 8,888 quarter-degree pixels by month. Temperature unequivocally rises in the region, but it rises relatively less along the coasts, particularly on the eastern side of the region. Precipitation has trended downward for much of the region since 1975, but relatively little change in precipitation is projected between the 2020s and the 2060s. Under the higher emissions “Paris Forever” scenario, we found that by the 2060s, the 1-in-20-year low-rainfall events will occur twice as frequently in most of the region, though it will occur less frequently in northwestern Angola. The 1-in-20-year high-rainfall events will occur 3 to 4 times as often in northeastern South Africa and twice as often in most of Angola.