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Africa is home to an estimated wild edible insect population of 1000 species that offer an opportunity for sustainable food systems while also improving food and nutrition security on the continent. Edible insect consumption has been part of African communities for a long time and forms part of their diets and cuisines, particularly within low-income households with limited resources. The purpose of our study was to investigate and review the contribution that edible insects can make towards the realisation of sustainable food systems, and environmental/planetary health including the fulfilment of Sustainable Development Goal number 2 (zero hunger). Our study applied a bibliometric analysis approach using VOS Viewer, a data mining software. The study established that the consumption of edible insects is still widespread across many African countries and therefore can be used as an avenue for improving environmental health and enhancing food systems on the continent through a reduction in meat-based diets. This, in the long term, will also reduce the emission of greenhouse gases such as carbon dioxide and methane from livestock production-related activities. Edible insects are also known to contain a high percentage nutrient content of proteins, fats and iron and, thus, can also play a vital role in reducing food insecurity and malnutrition, particularly within low-income households. Due to the existence of a high number of edible insect species on the continent, communities in Africa can easily access sources that can further be preserved using various indigenous techniques while also having minimal impact on the environment. In addition, being a source of nutritious food, edible insects can also be a source of establishing sustainable livelihoods, as well as being able to be commercialised, thus further creating employment opportunities and economic growth. Some of the notable edible insects in abundance on the continent include termites, ants, crickets and caterpillars. Our study recommends that Africa should commercialise edible insect production, in addition to preservation processing that leads to the eradication of perennial food insecurity and malnutrition and improves environmental health, as well as developing sustainable food systems. We also further recommend the establishment of food safety guidelines on edible insects as most African countries do not have such a plan in place currently.

Remote Sensing evapotranspiration models are critical in order to understand the cycling of water in the environment. Initially, an outline of the concepts related to evapotranspiration, as well as the shortcomings of land-based methods, is presented. The aim of the study was based on reviewing remote sensing evapotranspiration models which provide an alternative data source. These models have proved to be a cheaper alternative to mapping and estimating spatiotemporal evapotranspiration measurements across local and regional scales. This paper reviews the single-source energy balance model, which differs from the two-source model, for estimating spatiotemporal measurements of evapotranspiration. The single-source energy balance model is underpinned by mathematical equations which differentiate the various single-source evapotranspiration models (Surface Energy Balance Systems, Simplified Surface Energy Systems, Surface Energy Balance Algorithm, and Mapping Evapotranspiration at high Resolution and with Internalised Calibration). The soil surface and forest canopy components were observed to be the major difference between the single and dual-source models. Further advice was discussed on the implementation of the OpenET tool, which provides an open and accessible satellite-based estimation of evapotranspiration for improved water management.

Temporary freshwater pools or pans are known for their nature value and socio-economic importance especially in arid and semi-arid regions, but it is still poorly known how they develop in a natural setting. The ecologically valuable temporary freshwater pans of the Save Valley Conservancy in Zimbabwe, are studied in order to gain insights into their formation. Field observations of 17 existing pans and in situ measurements at one possible site of pan formation were done. It was observed that in most cases trees were bordering existing pans with Diospyros mespiliformis being present at eight locations and Colophospermum mopane at five. These two species were co-existing at two locations which had also dead trees present. On the basis of these observations, a suspected developing pan was followed up using hydrological field observations to understand processes that are important in pan formation. In situ infiltration tests as well as penetrometer tests, before and after a rainfall event, were completed on a grid covering 25 m2. The measurements were taken at one-metre interval and the data were krigged in order to visualise the contours. Initial insights point towards the areas in the immediate vicinity of trees acting as preferential pathways for infiltration, which is in contrast to what is needed for ponding. Based on these findings, we propose a possible theory for the formation of pans in the study area and suggest techniques for monitoring pan formation.

The current study aimed to determine the factors affecting groundwater recharge and its spatial distribution in the Rietvlei wetland located near Cape Town. To achieve this, the subsurface material was logged during the construction of eight shallow wells, complimented with field observations, and surveying the dug wells. The water stemming from these wells was sampled and analysed for Oxygen 18 and Deuterium to determine the source of groundwater in Rietvlei wetland. Downhole salinity logs of the wells were also undertaken, and rainfall samples were analysed for the stable isotopes. Isotopic results indicate that groundwater stems from rainfall, with the exception of Well 8 which has been influenced by the river due to its proximity to the surface water body. Additionally, results obtained indicate a distinct relationship between elevation and soil structure. Shallow profiles were mainly dominated by medium to fine sands, silty sand, and clay. Using the water table fluctuation method, this was found to have a direct impact on the spatial distribution of groundwater recharge on an event basis. It was therefore concluded that both lithology and topography have a direct effect on recharge rates and water quality.

Activity concentration and sensitivity of groundwater to radon contamination, and simple and sustainable radon mitigation possibilities have been studied and presented. Radon concentrations in groundwater at point of source (well site), point of use (homes), emission and exhalation rates from rock material (aquifer materials), as well as effects of mitigation measures (storing water in pot before use) of radon in drinking water from the area were also evaluated. Radon activity concentration (Bq/m3) in studied groundwater at point of source ranges between 731 ± 5 and 84,300 ± 530, and at point of use (homes) the mean values recorded range from 276 ± 14 to 8010 ± 98 Bq/m3. Radon emission and exhalation from aquifer materials in the area ranged between 62.5 ± 4–150 ± 10 Bq/m3 and 2.93–6.0 Bq/m2/h. It was observed that high radon concentration in the studied groundwater were recorded in well drilled in areas underline by granite and gneiss, where fractures were the main targets for groundwater abstraction. The study revealed that boreholes drilled in these areas and fitted with hand pump had the highest radon concentration. It is therefore concluded that radon distribution in groundwater of the area is closely related to the geology, structures (fractures), and wells type. It is observed that the traditional way of collecting and storing groundwater from wells in clay pot before use as practiced by inhabitant of the area resulted in reducing radon concentration at homes with as much as 94.95% in Kundiga and 62.24% in Jara Dali. Therefore, this can be regarded as a good, sustainable, and effective mitigation measures for radon gas-contaminated groundwater.

An aquifer in the semi-arid environment of Sutherland, South Africa is examined. The characterization of the saturated geological unit was completed by mapping associated dolerite dykes and fractured outcrops of Beaufort Group sedimentary rocks. This was complimented by pumping tests in order to better understand the fracture connectivity that was found to decrease with distance from a prominent dyke. Groundwater samples and precipitation samples in the study area were analysed for stable isotopes. Drill chips of selected boreholes were examined in order to also better understand the nature of the subsurface at the contact of the dolerite and a suspected subsurface feature identified through satellite imagery. The results are combined into a conceptual geohydrological model to gain insight into the groundwater flow dynamics of the area. Findings suggest preferential recharge occurs in the study area with higher hydraulic infiltration related to the river beds and fracture sets in the study area.

The application of gravity to Geohydrology is reviewed. A short background and history related to the application of geophysics to Geohydrology is outlined. Multiple works related to ground based gravimetry applied to the hydrological sciences in general are examined. These include the possible errors which might occur when applying gravimetry to hydrological studies. Furthermore, the satellite based applications of gravity for hydrology are also briefly outlined in order to compare to the aforementioned ground based gravity. Then a review of the most recent works related to hydrological modelling and correlation with residual gravity signals is shown in order to highlight the usefulness of this geophysical tool. International as well as African case studies are mentioned in order to highlight applicability. Thereafter a South African context of studies related to gravity is shown with a focus on the South African Geodynamic Observatory at Sutherland. Lastly the future outlook of gravity studies is examined in order to advance work in this arena and guide studies to come.

Author Summary: In recent times various studies have characterised the extent to which natural radioactive contamination is occurring within groundwater. Unfortunately there seems to be no standard sampling and monitoring protocol for radionuclides within secondary aquifers. A document of this nature is important due to the fact that a major part of South Africa is underlain by hard rock aquifers and they supply numerous towns with potable water for various uses.

An analysis of current available sampling and monitoring protocols related to radioactivity has been undertaken. The international best practice is outlined in order to better understand the available sampling as well as monitoring protocols related to radioactivity. Thereafter, the most relevant South African groundwater sampling and monitoring protocols are examined for their application to the subject matter. This piece of work highlights the need for more sampling and monitoring protocols related to fractured rock media in general and radioactivity in fractured rock media in particular.