Research Articles (Earth Sciences)

Permanent URI for this collectionhttps://hdl.handle.net/10566/273

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The potential for urban agriculture (UA) in Cape Town, South Africa: a suitability analysis
(Taylor and Francis Ltd., 2025) Musasa, Tatenda; Kanosvamhira, Tinashe P; Mupepi, Oshneck
Urban agriculture plays a pivotal role in enhancing human well-being by contributing to food security, economic prosperity, and environmental sustainability. Despite its significance, many cities lack accurate inventories to identify suitable sites for such initiatives. This study examines the potential for urban agriculture in Cape Town using Multi-Criteria Decision Making techniques. Factors such as temperature, soil fertility, road accessibility, and precipitation were analysed using weighted overlay to determine the agricultural potential in Cape Town. Utilizing methodologies like the Analytic Hierarchy Process and Weighted Linear Combination, the agricultural potential was established. Findings indicate that there are highly suitable areas for agriculture whose potential has not yet been fully exploited. Currently, agricultural activities like vineyards, crop production, and cattle farming, though situated on good agricultural land, are not as prominent despite the availability of vast tracts of highly suitable land. Therefore, there is a need to raise awareness and promote urban agriculture to alleviate poverty-related food insecurities. The implementation of urban agriculture is anticipated to significantly improve food security, create economic opportunities, and enhance environmental sustainability within urban areas. The study recommends the need for longitudinal studies to gather essential information for informed decision-making, ensuring the sustainability of urban agriculture initiatives.
Personal factors influencing emergency evacuation decisions under different flash flood characteristics
(Springer Science and Business Media B.V., 2025) Liu, Dedi; Xu, Yongxin; Zhang, Ruikang
Emergency evacuation has received more attention as an effective tool of flash flood disaster prevention that calls for systematic thinking rooted in natural and social sciences. Although personal factors influencing emergency evacuation decisions (EED) after receiving a flood warning have been widely discussed, few studies have referred this issue to the flash flood characteristics. This study explored the personal factors influencing EED under different flash flood characteristics (i.e., the frequency, occurrence time, and severity of flash floods) through field survey data. Three typical flash flood characteristics in three towns were selected as case studies. An ordinary logistical model and path analysis were used to analyze the independent influence and influence process of the personal factors on evacuation intention under the three flash flood characteristics. The results showed that personalized risk perception and warning type consistently influenced evacuation intention regardless of the flash flood characteristics, while the independent influence of flood experience and reliance on hazard information on evacuation intention was varied with the flash flood characteristics. Perceived exposure influenced evacuation intention through the mediations of flood experience when there were high-frequency, recent, and loss-causing flash floods, and of risk perception when there were low-frequency, distant, and few-loss-causing flash floods. The effect of warning type on evacuation intention was varied with the flash flood characteristics if the warning type changed from the suggestive rainstorm red warning to mandatory ready-to-evacuate warning. However, if the warning type changed from the ready-to-evacuate to immediate-evacuation warning, there was no significant difference in this effect regardless of the flash flood characteristics. Therefore, it is necessary to implement distinctive emergency management according to specific flash flood characteristics.
Wetland inundation and moisture dynamics in Tugwi-Zibagwe and Shashe sub-catchments, Zimbabwe: insights from 2017 to 2023
(Taylor and Francis Ltd., 2025) Dube, Timothy; Mupepi, Oshneck; Marambanyika, Thomas
We analysed the Modified Normalized Difference Water Index (MNDWI) from Sentinel-2 Level 1 C and the Topographic Wetness Index (TWI) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation model (DEM). Total inundated wetland area dropped by 0.1% in the Tugwi-Zibagwe and by 0.2% in the Shashe between 2017 and 2023. Significant correlations between temperature and rainfall impacts were observed in the Shashe sub-catchment (r = −0.84; p = .02 and r = 0.77; p = .04), whereas in Tugwi-Zibagwe, these correlations were less pronounced (r = −0.60; p = .15 and r = 0.39; p = .39). Between 2017 and 2023, large and small seasonal wetlands fluctuated between 60.2% and 35.9% of the total wetland area in Shashe whilst in Tugwi-Zibagwe it varied from 17.4% to 14.9%. The findings underscore the critical importance of conserving and restoring small (<1 ha) unprotected wetlands in rural semi-arid regions.
Appropriate spatiotemporal scale selection for water use simulation in China
(Elsevier B.V., 2025) Xu, Yongxin; Liu, Dedi; Zhang, Jiayu
Water use simulation plays a pivotal role in water resource management globally. Simulating water use at regional raster scale enables better alignment with available water resources, facilitating efficient allocation. However, there remains a deficiency in methods of spatiotemporal scale selection for ensuring the simulation accuracy while also guaranteeing the information density at each raster scale. A novel framework has been proposed to select the appropriate spatiotemporal scales for water use simulation. The framework utilizes an iterative input variables selection (IIS) algorithm to identify optimal input variables for water use simulation and an end-to-end deep learning-based spatiotemporal scale adaptive selection (SSAS) model to determine the appropriate spatiotemporal scales. Due to China's substantial population, water demand, and the growing challenges of global warming, the country is particularly susceptible to water scarcity. The proposed framework was applied to select the appropriate spatiotemporal scales for simulating irrigation, domestic, and industrial water use across 341 prefectures in China. The results indicate that the appropriate spatial scales for irrigation water use simulation range from 1 km to 5 km in most places, while they vary from 1 km to 4 km for domestic and industrial water use simulation. Furthermore, the appropriate temporal scale generally spans from 10 days to 45 days for all three types of water use simulation. It is interesting to find that the simulation accuracy is significantly impacted by the selection of appropriate temporal scales through the parameter sensitivity analysis. Our proposed framework supports water resource management and facilitates efficient water resource allocation to mitigate water scarcity.
African humanitas: ubuntu and the global response to climate change
(Springer Science+Business Media, 2025) Chitando, Ezra; Mlambo, Kudzanai Melody; Mlambo, Obert Bernard
The human dimension within the climate change debate, involving the African ideals of Ubuntu, is persuasive and motivational in the fight against climate change. The chapter discusses the impact of Ubuntu praxis on the environment. It reflects on different forms of inequality that Ubuntu is strategically placed to addressed in the wake of climate change. Climate change has been linked to the loss of biodiversity, flooding, tsunamis and extreme heat waves, among other challenges. Our inclusion of an Ubuntu ethos in the climate change debate is an effort to relate African humane virtues to growing concerns about deteriorating environmental and climatic conditions worldwide. We explore how African humanitas (Ubuntu) promotes and establishes an important environmental ethos. We posit that Ubuntu can serve as a valuable resource in the global response to climate change.
Assessing spatially-compounding drought probabilities in inter-basin water diversion: insights from the Tao River water diversion project in China
(Elsevier B.V., 2025) Liu, Dedi; Zhou, Wan; Cheng, Yufei
Study regions The water-donating (Tao River Basin, TRB) and water-receiving (Zuli River Basin, ZRB, and Wei River Basin, WRB) regions of the Tao River Water Diversion Project (TRWDP) in Gansu Province, China. Study focus Inter-basin water diversion projects are critical for mitigating water shortages in arid and semi-arid regions. By addressing misestimations arising from solely precipitation-based analyses, this study integrates meteorological and hydrological perspectives to explore spatially-compounding drought probabilities between the water-donating and water-receiving regions. Moreover, the meteorological-hydrological propagation is explored using correlation analysis, runs theory and copula functions, while variance decomposition is applied to identify the dominant climatic drivers. New hydrological insights for the region Results show that: 1) Spatially-compounding hydrological droughts occur less frequently than meteorological droughts due to varying geomorphologies and human activities. From 1970–2020, meteorological droughts occurred in five years, while only one hydrological drought event (2016) was identified across the three sub-basins, which was not detected by meteorological indices. The probability of severe spatially-compounding droughts varies regionally, with a higher joint probability in TRB–WRB than in TRB–ZRB, highlighting regional differences in drought propagation. 2) Meteorological and hydrological droughts exhibit distinct seasonal propagation characteristics, with short PTs in summer and autumn due to rapid hydrological responses and longer PTs in winter and spring due to delayed runoff generation. Basins with short PTs require real-time monitoring and rapid response strategies, while those with prolonged PTs need adaptive measures. 3) Precipitation and temperature are the primary climatic drivers of drought, with extreme climatic indices—monthly maximum of daily minimum (TNx) and maximum (TXx) temperatures—contributing the most. The decline in Rx5day (maximum five-day precipitation) suggests a decreasing frequency of extreme rainfall events, further intensifying drought propagation. These findings improve understanding of concurrent droughts and provide practical insights for drought mitigation and sustainable operation of inter-basin water diversion project.
Statistical modelling of spatio-temporal rainfall trends, dependence, and extremes in Zimbabwe (1984–2024)
(Springer, 2025) Dube, Timothy; Hove, Kudakwashe; Nyamugure, Philimon
Understanding the spatio-temporal variability of extreme rainfall is critical for climate adaptation and for informed water-resource planning in Zimbabwe. This study develops a unified statistical framework to: (1) characterize annual rainfall variability and detect monotonic trends; (2) model extreme rainfall events via block maxima and peaks-over-threshold methods and quantify their long-range dependence; (3) assess the spatial autocorrelation patterns of rainfall across provinces; and (4) explore inter-provincial rainfall dynamics using a Vector Autoregressive (VAR) model. Monthly rainfall totals for ten provinces (1984–2024) were retrieved from NASA POWER at provincial centroids. Descriptive statistics reveal a pronounced east–west gradient in mean annual rainfall (390.1 mm in Manicaland; 190.8 mm in Matabeleland South) and variability (Standard deviation up to 147 mm in Manicaland). The Mann–Kendall and block-bootstrap tests indicate no significant monotonic trends (all 0.16), suggesting stationary annual totals over the study period. Extreme-value analysis shows uniformly positive Generalized Extreme Value (GEV) shape parameters (for example) with anomalously large estimates in Harare and the Midlands; Generalized Pareto Distribution (GPD) fits yield moderate heavy-tails () and scale parameters of 5.6–9.9 mm. Detrended fluctuation analysis produces Hurst exponents (0.25–0.35), indicating anti-persistence and mean-reversion in extreme-rainfall maxima. Spatial autocorrelation metrics (Global Moran’s I = 0.266; Geary’s) confirm significant clustering. Local Moran’s I identifies northeastern hot-spots and southwestern cold-spots. A VAR(2) model—selected via minimum Akaike Information Criterion/Bayesian Information Criterion (also known as the Schwarz Criterion)(AIC/BIC)—highlights significant two-month persistence in Manicaland (,) and one-month memory in Matabeleland North (,). These findings reveal heterogeneous heavy-tailed behaviour, mean-reversion, and spatial clustering in Zimbabwe’s rainfall extremes, underscoring the need for region-specific risk assessments and infrastructure design tailored to local hydro-climatic regimes.
Enhancing target crop discrimination: a novel shadow detection technique for RGB datasets in mixed agricultural environments
(Mapping Sciences Institute Australia, 2025) Dube, Timothy I.; Sibanda, Mbulisi; Mafuratidze, Pride
Shadows pose significant challenges in smallholder farming systems, where mixed cropping is common. This study introduces two novel techniques: the Hue-Intensity-Green-Blue (HIGB) difference method for shadow detection and the Light Intensity Ratio-Based (LIRB) method for shadow compensation. Their performance was tested against the C3 and NSVDI models using five accuracy metrics on RGB imagery. HIGB consistently achieved superior accuracies (77–95%) compared to NSVDI (63–84%) and C3 (69–81%) in five different crop mixtures. Both the models, HIGB and LIRB, provide an integrated, robust solution for shadow detection and compensation in heterogeneous agricultural environments.
Variability in the carbon management index and enzymatic activity under distinct altitudes in the alpine wetlands of Lesotho
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Mazvimavi, Dominic; Nthebere, Knight; Marake, Makoala Vitalis
Alpine wetlands, key carbon sinks and biodiversity hubs, remain understudied, especially under climate change pressures. Hence, the present study was conducted to assess the variability in soil enzyme activity (SEA) and the carbon management index (CMI) and to utilize principal component analysis (PCA) to explore the variation and correlation between SEA and CMI as influenced by altitudinal gradients in alpine wetlands. This information is essential for exploring the impacts of soil degradation and guiding restoration efforts. The study was designed in blocks (catchments) with six altitudinal variations (from 2500 to 3155 m a.s.l), equivalent to alpine wetlands from three catchments (Senqunyane, Khubelu and Sani) as follows: Khorong and Tenesolo in Senqunyane; Khamoqana and Khalong-la-Lichelete in Sani; and Lets’eng-la-Likhama and Koting-Sa-ha Ramosetsana in Khubelu. The soil samples were collected in February 2025 (autumn season, i.e., wet season) at depths of 0–15 and 15–30 cm and analyzed for bulk density, texture, pH, electrical conductivity (EC), soil organic carbon (SOC), SEA, and carbon pools, and the CMI was computed following standard procedures. The results demonstrated that the soil was loam to sandy loam and was slightly acidic and non-saline in nature in the 0–15 cm layer across the wetlands. The significant decreases in SEA were 45.33%, 32.20% and 15.11% (p < 0.05) for dehydrogenase, fluorescein di-acetate and β-Galactosidase activities, respectively, in KSHM compared with those in Khorong (lower elevated site). The passive carbon pool (CPSV) was dominant over the active carbon pool (CACT) and contributed 76–79% of the SOC to the total organic carbon, with a higher CPSV (79%) observed at KSHM. The CMI was also greater (91.05 and 75.88) under KSHM at the 0–15 cm and 15–30 cm soil depths, respectively, than in all the other alpine wetlands, suggesting better carbon management at higher altitudinal gradients and less enzymatic activity. These trends shape climate change outcomes by affecting soil carbon storage, with high-altitude regions serving as significant, though relatively less active, carbon reservoirs. The PCA-Biplot graph revealed a negative correlation between the CMI and SEA, and these variables drove more variation across sites, highlighting a complex interaction influenced by higher altitude with its multiple ecological drivers, such as temperature variation, nutrient dynamics, and shifts in microbial communities. Further studies on metagenomics in alpine soils are needed to uncover altitude-driven microbial adaptations and their role in carbon dynamics.
Impacts of diagenetic alterations on siliciclastic sediments of the pletmos basin: implications for reservoir quality
(Springer Science and Business Media Deutschland GmbH, 2025) Oghenekome, Monica Enifome; Chatterjee, Tapas Kumar; Van Bever Donker, Jan M.
The Pletmos sub-basin of Outeniqua Basin, South Africa hosts heterogeneous siliciclastic reservoirs sediments deposited under a complex tectonic setting and its diagenetic processes remain largely undefined. This study focuses on Cretaceous reservoir sediments, aiming to evaluates the impact of diagenetic alterations on the reservoir quality. Despite the basin’s recognition as a prolific hydrocarbon prospect, no detailed investigation into the diagenetic evolution of its reservoir rocks is available. This is the first integrated Petro-sedimentological characteristics in the basin, combining petrographic and petrophysical data derived from conventional core samples of 100% recovery and well logs data from three exploratory wells. The siliciclastic reservoirs are primarily composed of moderately to poorly sorted feldspathic litharenites and lithic arkoses sandstones deposited in fluvial environment. Two major porosity–permeability trends are identified; due to primary intergranular pore networks and secondary porosity generated by mineral dissolution. High effective porosity is attributed to the coexistence of preserved primary pores and timely development of secondary porosity, supporting enhanced fluid migration and reservoir quality. Diagenetic processes include early mechanical compaction, quartz and clay cementation, calcite and iron oxide precipitation, and extensive feldspar dissolution into kaolinite. Authigenic chlorite coatings, variations in quartz and calcite cementation are especially influential in porosity distribution. These changes reflect eogenetic and mesogenetic phases, which significantly modify petrophysical properties. The reservoir porosity ranges between 13.5 and 16.3%, primarily controlled by grain compaction, quartz, calcite cementation, and mineral dissolution. Diagenesis directly influences reservoir quality, making this study a valuable reference for reservoir assessment, exploration, and regional diagenetic comparison.
A general chopping peak function for a reservoirs group flood control regulating
(Elsevier B.V., 2025) Liu, Dedi; Mu, Zhenyu; Wang, Zhenyu
Flood event is one of the natural hazards and has affected the most people in the world. As the peak of the flood event is the most striking feature to its hazard, chopping flood peak is often the main goal of preventing flood hazard. To integrate the regulation of the flood storages in a reservoirs group for chopping flood peak, a general relationship among the flood events, the flood storages and the chopping peak has been quantified through Chopping Peak Function (CPF). And we have derived the analytical solutions for a single, a parallel or a cascade reservoirs group while numerical solution for a mixed reservoirs group to their corresponding CPF. Based on the solutions to their CPF, the mechanism is clarified for the integrated reservoirs flood storages regulation. The derived analytical solutions have also been proven to be more efficient for integrating the reservoirs regulation than for only every single reservoir regulation. The numerical solutions for the mixed reservoirs groups are found to be better than that of optimal reservoirs regulation model through NSGA-II in terms of the number and the distribution range of the Pareto frontier. Therefore, our study will not only help understand the regulation of the f lood storages in reservoirs groups for chopping flood peak, but also find an efficient way to prevent flood hazard.
The southwesternmost piece of the Grenville Orogen in Laurentia – New U-Pb and Sm-Nd ages, and P-T estimates from the Sierra del Cuervo, Chihuahua, Mexico.
(Elsevier B.V, 2025) Frei, Dirk; Weber, Bodo; Nayeli Chacón-Olivas C.
This paper elucidates the origin and tectonic setting of Mesoproterozoic metaigneous rocks of the Sierra de Cuervo, Chihuahua, Mexico, providing new evidence for the southwestern extension of the Grenville Orogeny in North America. Several geochronological approaches were used, including U-Pb zircon dating by LA-ICP-MS and the Sm-Nd isochron technique, using ID-TIMS. Igneous zircon domains reveal crystallization ages for felsic igneous protoliths ranging from ~ 1.38 Ga to ~ 1.33 Ga, with ~ 1.42 b.yr. old inherited zircon. Whole-rock SmNd isotopic data define an isochron at 1.52 ± 0.03 Ga, suggesting crustal growth during the early Mesoproterozoic. The timing of metamorphism is constrained by Sm-Nd leached garnet-whole-rock isochrons and by U-Pb zircon dates between ~ 1.06 and ~ 1.05 Ga. Metamorphic pressure and temperature conditions were estimated from a metamafic rock sample at 6.4 ± 1 kbar and 520 ± 20 ◦C using conventional geothermobarometry and pseudosection modeling. The results contextualize the Precambrian rocks of the Sierra del Cuervo with metamorphic rocks of the West Texas Uplift thrust over the Laurentian margin. We propose that this thrust represents a remnant of the unexposed Grenville Front and that the Chihuahua and West Texas metamorphic basement is characterized by contemporaneous magmatism and reworked from the Granite-Rhyolite Province of the North American midcontinent during the Grenville Orogeny, comparable to the low-medium pressure allochthonous Ottawan metamorphic belt of the Grenville Province in Canada
Short-term effects of cover crop species and termination methods on soil ph and key enzymatic activities (β-glucosidase, phosphatase and urease activities) in a citrus orchard (eureka lemons)
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Jovanovic, Nebo; Silwana, Sibongiseni; Mulidzi, Azwimbavhi Reckson
The best management practices for cover cropping in citrus orchards, particularly in terms of species selection and termination methods, remain unclear. This study assessed the short-term effects of different cover crop species (vetch, medics and oats) and termination methods (slashed vs. non-slashed) on soil pH and enzyme activities (β-glucosidase, acid phosphatase, and urease) in a citrus orchard with sandy soil. A randomized complete block design with a factorial treatment structure and six replications was used. Soil samples were collected before and one year after cover crop establishment. The results showed that cover cropping increased soil pH from 5.42 to 6.00 after one year. However, no statistically significant differences were observed in soil pH or enzyme activities among cover crop species or termination methods. Marginal increases in enzyme activities were observed under leguminous cover crops, and these changes were insufficient to indicate strong treatment effects. Correlation and principal component analyses revealed that soil enzyme activities were more strongly influenced by soil properties (depth, carbon content and moisture) than by cover crop species or termination methods. These findings suggest that, under sandy soil conditions and within a one-year period, cover cropping has limited immediate effects on soil biological indicators in citrus orchards. Longer-term studies are recommended to assess cumulative impacts
Impacts of inter-basin water diversion projects on the feedback loops of water supply–hydropower generation–environment conservation nexus
(Copernicus Publications, 2025) Liu, Dedi; Wang, Jiaoyang; Guo, Shenglian
To balance water resource distribution in different areas, inter-basin water diversion projects (IWDPs) have been constructed around the world. Unclear feedback loops of water supply-hydropower generation-environment conservation (SHE) nexus in IWDPs increase the uncertainty in rational scheduling of water resources for water receiving and water donation areas. To address the different impacts of IWDPs on a dynamic SHE nexus and explore synergies, a framework is proposed to identify these impacts across multiple temporal and spatial scales in a reservoir group. The proposed approach was applied to the Hanjiang River Basin (HRB) in China as a case study. Runoff series from the HRB at multiple temporal and spatial scales were provided through the Variable Infiltration Capacity hydrological model. Multi-level ecological flows were determined by the modified Tennant method based on a multi-level habitat condition method. 30 scenarios were set and modeled in a multisource input-output reservoir generalization model. Differences between scenarios were quantified with a response ratio indicator. The results indicate that without IWDPs there is negative feedback between water supply (S) and hydropower generation (H) and between S and environment conservation (E), while there is positive feedback between H and E. The negative feedback of S on H and the positive feedback of E on H are weakened or even broken in abundant-water periods. With IWDPs, water donation basins experience strengthened feedback loops, while water receiving basins experience weakened feedback loops. Feedback loops exhibit intrinsic similarity and stability across different time scales. Feedback loops in reservoirs with a regulation function remain stable under varying inflow conditions and feedback loops for downstream reservoirs are influenced by their upstream reservoirs, especially in low-flow periods. Simply increasing water receiving flow cannot resolve inherent SHE conflicts because of the persistent feedback polarity with IWDPs, and adaptive allocation rules are needed that account for these stable feedback patterns. The proposed approach can help quantify the impacts of IWDPs on SHE nexus and contribute to the sustainable development of SHE nexus.
Proximity to water shapes the distribution of natural elephant mortality in Hwange National Park, Zimbabwe
(Nature Research, 2025) Mpakairi, Kudzai Shaun; Kavhu, Blessing; Ngwenya, Nobesuthu
While elephant poaching has received considerable attention, natural mortality can at times surpass human-induced deaths, especially under environmental stress. Understanding the ecological drivers of natural elephant mortality is therefore crucial for informing reintroduction efforts and preventing mass die-offs. In this study, we investigated environmental predictors of natural elephant mortality in Hwange National Park, Zimbabwe, using mortality records from 2020 to 2022. We applied four machine learning species distribution models, Random Forest, Gradient Boosting, Maximum Entropy, and Extreme Gradient Boosting, along with their ensemble to model mortality hotspots. The ensemble model outperformed individual models, achieving a True Skill Statistic of 0.54 and a Receiver Operating Characteristic of 0.83. Among all predictors, distance to water sources was the most influential variable (accounting for > 55% of model importance), with most mortalities occurring within 6 km of water points. Other key predictors included climate water deficit, normalized difference vegetation index (NDVI), tree cover percentage, and elephant density (each contributing > 5%). In contrast, maximum temperature of the warmest month and elevation had minimal predictive power (< 4%). Our results provide actionable insights for conservation planning. Areas close to water sources, particularly during dry periods, should be prioritized for monitoring and veterinary intervention. Meanwhile, regions with historically low mortality prevalences may serve as safer sites for reintroduction. This spatially explicit framework can help reduce post-release losses and enhance the long-term success of elephant conservation initiatives, especially in the face of ongoing environmental change.
Fine-scale mapping of irrigation suitability in South Africa using ensemble modelling
(Nature Research, 2025) Mpakairi, Kudzai Shaun; Dube, Timothy; Sibanda, Mbulisi
Food insecurity, exacerbated by a growing population and environmental change, poses a significant challenge in Southern Africa. Enhancing agricultural productivity through efficient irrigation practices is crucial for achieving food and water security and sustainable development goals. This study applied an ensemble modelling approach to identify and assess irrigation suitability areas across South Africa, combining the predictive power of Random Forest, Extreme Gradient Boosting (XGBoost), and Gradient Boosting Machine (GBM) algorithms. These machine learning models were applied using cropland presence/pseudo-absence data and a suite of predictor variables. The ensemble model, leveraging a weighted averaging approach based on individual model performance, outperformed the individual models, achieving a TSS of 0.66 and an AUC of 0.90. Land use, population density, and elevation were identified as key factors determining irrigation suitability. The ensemble model also revealed substantial spatial variation in irrigation potential across South Africa, with the Northern Cape and Western Cape provinces exhibiting the largest suitable areas. The results provide critical information for targeted irrigation development, enabling efficient resource allocation, and maximising agricultural productivity. This data-driven approach offers a robust framework for sustainable agrarian planning in the face of increasing food demands and climate change, contributing to enhanced food security and economic development in South Africa.
Long-term land use and land cover dynamics in the Okavango River Basin: impacts on wetlands ecohydrological conditions using satellite data and machine learning
(Routledge, 2025) Sigopi, Maria; Moropane, Lebogang Mmasechaba; Dube, Timothy
The Okavango River Basin (ORB), one of sub-Saharan Africa’s most ecologically significant and well-preserved endorheic system, is critical for sustaining biodiversity and providing ecosystem services. However, increasing anthropogenic pressure and environmental change demand continuous and precise monitoring to safeguard its natural assets. This study utilized Google Earth Engine (GEE) to present a robust 34-year (1989–2023) analysis using Landsat 5 and 8 at 30 m resolution. The study examined the relationship between the normalized difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI), and normalized difference phenology index (NDPI), coupled with Climate Hazards Group Infrared Precipitation (CHIRPS), ERA5 Land, and TerraClimate products. Utilizing a Random Forest (RF) classifier, we achieved accuracies of 95-98% across nine intervals. Wetlands maintained 3% coverage from 1989-2004, while forest occupied 20-26%. Water bodies declined from 1989-2016, then gained 6419 km2 (2017–2020). Wetlands gained 19144 km2 (1989–1992) and 8406 km2 (2017–2020), but lost -10986 (1993–1996) and -7734 km2 (2009–2012). Higher temperatures are correlated with NDPI (β = 0.05, p = 0.003, R2 = 0.32) and NDVI (β = 0.106, p = 0.0045, R2 = 0.29), while precipitation and evapotranspiration were not significant. SAVI presented no significant relationship (R2 = 0.27, p = 0.027). These findings underscore the urgent need for continuous LULC monitoring to inform adaptive management strategies for the ORB.
In the minor key: the minuscular mycelium and its implications for citizen science
(John Wiley and Sons Inc, 2025) Goldin, Jaqui; Suransky, Carolina
In an era marked by ecological precarity and growing demands for knowledge systems that are more inclusive, situated, and responsive, grassroots initiatives have begun to challenge dominant models of science and expertise. Among these, citizen science has emerged as a powerful mode of inquiry that brings together university-based scientists with communities to highlight lived experience, local knowledge, and collective sense-making. One such initiative, which is grounded in a commitment to care, justice, and co-creation is the project Diamonds on the Soles of our Feet (DSF) which originated as a locally rooted water literacy project in the province of Limpopo in South Africa. Since its inception in 2019, the project has evolved in unexpected, generative and at times even unfathomable ways. From its start in one rural village, it grew into a multi-sited, transnational, and increasingly entangled exploration of environmental justice and relational care. This paper seeks to make sense of these developments through the conceptual lens of a ‘fungal turn’ and the aesthetics of care. Engaging with the entanglements of citizen science, we found, can open up forms of learning that stretch beyond conventional scientific frameworks. Here the image of the fungal as a (dis)organizing principle allows us to contrast it with the more rigid image of science as a container. As DSF networ(ld)s extend into uncharted geographical terrains, the application of an ethics of care, coupled with fungal imagery, offers a valuable lens to interpret the unexpected and indeterminate textures that characterize our unfolding DSF journey. By equipping both learners and educators, DSF aims to create a collaborative model that supports long-term behavioral change and where authentic, value-transparent conversations become the fertile ground for meaningful engagement. We thus aim to create a pedagogy of connection, one that links ecology, identity, and imagination, resisting the impulse to fix, explain away or simplify, but instead to cultivate the capacity to remain present with the troubling complexity of it all. Once we took citizen science out of the container, we began to inhabit a space where encounters became unpredictable, often uncomfortable and occasionally deeply troubling. By resisting the impulse to command, to classify and to control and by resting instead in the minor key, meaning in the unfolding process rather than the singular event, we allowed ourselves to become entangled. Mushrooms offer more than a biological metaphor; they become a lens to reimagine ecological entanglement and the often-invisible networks that shape our understanding of science, learning, and care.
Nanoscale mapping of ZrSiO4phases in naturally shocked zircon using electron energy loss spectroscopy
(Walter de Gruyter GmbH, 2025) Kovaleva, Elizaveta; Roddatis, Vladimir; Syczewski, Marcin
Coexistence in natural samples of zircon (ZrSiO4) and reidite (a high-pressure polymorph of ZrSiO4) is attributed to the effects of hypervelocity impact events. The grains and intergrowths in those minerals can be merely a few nanometers in size, which makes phase identification by standard methods of structure analysis difficult. However, analytical scanning transmission electron microscopy (STEM) utilizing electron energy loss spectroscopy (EELS) can provide important information on phase transition mechanisms and pressure-temperature conditions associated with the shock event at the nanoscale. Here we demonstrate that the valence as well as oxygen core-loss EELS can be employed for nanoscale mapping of zirconreidite distributions in zircon-reidite aggregates. Moreover, other accompanying phases, e. g., baddeleyite, could also be identified and mapped by this method. We further compare the EELS maps with a 4D-STEM nanobeam precession electron diffraction data, and demonstrate the advantages of the EELS mapping, which provides spatial resolution down to the nanometer scale and is independent of crystal orientation.
Integrated water resources management for sustainable development in East and Southern Africa
(Elsevier Ltd, 2025) Dube, Timothy; Dzwairo, Bloodless Rimuka; Kgabi, Nnenesi
The 23rd WaterNet/WARFSA/GWP-SA Symposium was held at Sun City Conference Centre, in South Africa and online from 19 to October 21, 2022. The symposium, whose main theme was “Integrated Water Resources Management for Sustainable Development in East and Southern Africa”, drew over 400 participants from the academia, practitioners, policy makers and development partners from the Eastern and Southern Africa (ESA) region and beyond. The symposium was jointly convened by the International Association of Hydrological Sciences (IAHS), AU/NEPAD Southern African Network of Water Centres of Excellence (AU/NEPAD SANWATCE), and the Local Organizing Committee led by the North-West University, South Africa, with support from the Government of South Africa.

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