Extreme rainfall associated with mid-tropospheric cut-off low (COL) pressure systems affected the entire east coast of South Africa during April 2022, leading to flooding and destruction of homes, electricity power lines, and road infrastructure, and leaving 448 people confirmed dead. Therefore, this study investigated the evolution of the two COLs and their impacts, including the occurrence of extreme rainfall and cold weather over the southeast coast of the country. We analysed observed and reanalysis meteorological data and mapped areas at risk to impacts of flood hazards on the east coast of South Africa. Extreme rainfall (>500 mm) accumulated over 16 days was observed along the east coast, with the amount of rainfall progressively decreasing inland. We found that the rainfall associated with the first COL was significantly enhanced by the interactions between a strong low-level onshore airflow across the Agulhas Current and the coastal escarpment, resulting in deep convection and lifting. An unusual surface cyclone with tropical characteristics developed over the subtropical southwest Indian Ocean, driving onshore southeasterly winds which enhanced low-level convergence. Moreover, the flood risk results revealed that, amongst others, land cover/use (52.8%), elevation (16.8%) and lithology (15.5%) were the most important flood predictor variables in this study. Much of the study area was found to have very low (28.33%), low (31.82%), and moderate (21.66%) flood risk, whilst the high- and very-high-risk areas accounted for only 17.5% of the total land area. Nonetheless, the derived flood risk map achieved an acceptable level of accuracy of about 89.9% (Area Under Curve = 0.899). The findings of this study contribute to understanding extreme rainfall events and the vulnerability of settlements on South Africa’s east coast to flood risk, which can be used towards natural disaster risk reduction.

Upper air temperature measurements are critical for understanding weather patterns, boundary-layer processes, climate change, and the validation of space-based observations. However, there have been growing concerns over data discrepancies, the lack of homogeneity, biases, and discontinuities associated with historical climate data records obtained using these technologies. Consequently, this article reviews the progress of utilizing radiosondes and space-based instruments for obtaining upper air temperature records. A systematic review process was performed and focused on papers published between 2000 and 2023. A total of 74,899 publications were retrieved from the Google Scholar, Scopus, and Web of Science databases using a title/abstract/keyword search query. After rigorous screening processes using relevant keywords and the elimination of duplicates, only 599 papers were considered. The papers were subjected to thematic and bibliometric analysis to comprehensively outline the progress, gaps, challenges, and opportunities related to the utilization of radiosonde and space-based instruments for monitoring upper air temperature. The results show that in situ radiosonde measurements and satellite sensors have improved significantly over the past few decades. Recent advances in the bias, uncertainty, and homogeneity correction algorithms (e.g., machine learning approaches) for enhancing upper air temperature observations present great potential in improving numerical weather forecasting, atmospheric boundary studies, satellite data validation, and climate change research.

Heavy metal and microbial pollution in groundwater raises health concerns due to its adverse effects. This study aimed to assess the health risks associated with heavy metal and bacterial pollution in groundwater in Mankweng. Heavy metals and Escherichia coli were detected using inductively coupled plasma mass spectrophotometry and a Colilert system, respectively. The heavy metal pollution index (HPI) and non-carcinogenic and carcinogenic risks were computed. The β-Poisson dose–response model was employed to predict the probability of E. coli infection. The metals’ concentrations were all within the permissible limits of the South African National Standard (SANS). However, Pb levels at sites E and G exceeded the World Health Organization (WHO) guideline (≤0.01 mg/L). HPI values were all less than 100, indicative of low contamination. The hazard quotient values were all less than 1, except for vanadium. The cumulative cancer risk ranged between 3.06 × 10⁻⁵ and 1.81 × 10⁻⁴ and between 3.55 × 10⁻⁵ and 2.20 × 10⁻⁴ for adults and children, respectively. E. coli was only detected at site L. The annual risk of E. coli infection exceeded the WHO risk limit of 10⁻⁴. The results underscore the need for the regular monitoring of groundwater.

1. Soil is one of the most significant natural resources on Earth, it offers essential nutrients, minerals, and water for plant growth (Banerjee and van der Heijden 2023). Nutrients including Nitro...

There is a lack of groundwater quality monitoring, especially in developing countries like South Africa. This study aimed to evaluate borehole water quality. Groundwater was analysed for pH, dissolved oxygen (DO), temperature, electrical conductivity (EC), total dissolved solids (TDSs), turbidity, chemical oxygen demand (COD), nitrogen (N), sulphate (SO₄²⁻), fluoride (F⁻), chloride (Cl⁻), calcium (Ca²⁺), magnesium (Mg²⁺), potassium (K⁺), and sodium (Na⁺) using a multi-parameter device, spectrophotometer, turbidity meter, and inductively coupled plasma optical emission spectrophotometer. Total coliforms and Escherichia coli were quantified using the Colilert system. The water quality index (WQI) was calculated using the arithmetic weighting method. The parameters ranged as follows: pH (6.71–7.94), DO (2.19–7.79 mg/L), EC (379.67–1317.33 µS/cm), TDSs (190–659 mg/L), temperature (16.75–22.31 °C), turbidity (0.17–3.21 NTU), COD (9–50 mg/L), F⁻ (0.17–2.09 mg/L), Cl⁻ (36.1–184.55 mg/L), N (0.64–28.56 mg/L), SO₄²⁻ (27.18–112.13 mg/L), K⁺ (1.71–21.77 mg/L), Ca²⁺ (29.59–134.59 mg/L), Mg²⁺ (16.72–110.78 mg/L), and Na⁺ (38.52–170.63 mg/L). One borehole was polluted with E. coli (9 MPN/100 mL) and 25% were contaminated with coliforms beyond 10 MPN/100 mL. The WQI ranged from 50.430 to 190.220. The results underscore the importance of regular monitoring of groundwater.

Upper-air temperature and humidity measurements from radiosondes are critical for monitoring atmospheric stability and climate trends. However, historical records can be affected by biases, inhomogeneities, and discontinuities, particularly during instrument transitions such as from RS92 to RS41. Ensuring long-term data homogeneity is therefore essential for reliable climate assessment. This study quantifies systematic biases in RS92 and RS41 radiosonde measurements at the Beltsville GRUAN Station, USA (2017–2020), and compares them with COSMIC-1 radio-occultation (RO) temperature and humidity profiles. Both daytime and nighttime profiles were analysed using mean differences, Bland–Altman plots, Taylor diagrams, and quadratic linear regression. Results indicate mean temperature biases between RS92 and RS41 of 0.08–0.39 K, with RMSE ranging from 0.47 to 0.93 K in the stratosphere (15–35 km). Bland–Altman analysis revealed temperature differences of −1 to 2 K and relative humidity biases of −9% to 5% across 1000–200 hPa. Comparisons with COSMIC-1 revealed strong correlations (r = 0.98–0.99, p < 0.05) and normalized SDs of 0.15–0.6 K for temperature and relative specific humidity errors of 5–25%, with larger deviations occurring in the upper troposphere where absolute humidity is low. These findings underscore the importance of global, long-term monitoring and calibration to enhance the quality of radiosonde data, which is essential for understanding atmospheric processes and improving climate change detection.