ERA5 geopotential heights (m) at 500 hPa and SAWS daily rainfall (mm) over South Africa during the period 6-21 April 2022.
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...
Contexts in source publication
... the developing (8-9 April) stage of the first system, some rainfall activities were observed over the central parts of the country due to the presence of the upper trough. Rainfall amounts between 20 and 80 mm were observed over the central and northern parts of the country as the system became fully developed on 10 April ( Figure 5). High accumulation of rainfall was observed over the southeastern parts of the country in KwaZulu-Natal Province, exacerbated by the identified easterly gale force winds which led to high moisture advection from the South Indian Ocean. ...
... the developing (8-9 April) stage of the first system, some rainfall activities were observed over the central parts of the country due to the presence of the upper trough. Rainfall amounts between 20 and 80 mm were observed over the central and northern parts of the country as the system became fully developed on 10 April (Figure 5). High accumulation of rainfall was observed over the southeastern parts of the country in KwaZulu-Natal Province, exacerbated by the identified easterly gale force winds which led to high moisture advection from the South Indian Ocean. ...
... As was discussed before, predicting flood risk is a highly complex process because it depends on a large number of parameters such as rainfall, topography, and temperature mentioned by Mashao et al. (2022). The purpose of this study was to determine the most vulnerable area for flooding along with the south-west coastal region of Bangladesh, using historical data on water levels and demographic statistics. ...
Flood is a frequent experience for the people living in Bangladesh, especially in the south-western region. But due to its complexity and multidisciplinary nature, flood management remains a very difficult task. This research focused on finding the most vulnerable areas to flooding for each polder within the Khulna and Satkhira districts since those areas can be identified as one of the most vulnerable areas to flooding. Water level data from fourteen stations of seven rivers (Sibsa, Rupsa-Pasur, Kobadak, Bhadra, Kobadak, Ichamati (Western Border), Betna-Kholpetua, and Satkhira Khal) were analyzed to calculate water levels for 2, 5, 10, 25, and 100-year return period applying normal distribution, extreme value type-I (EV-I), and log person type-III (LP-III) distribution methods. The EV-I distribution method was showing the best fit. The study revealed that station SW243 (Rupsa-Pasur River) in the Dacope region has the most extreme water level, station SW259 (Sibsa River) has the second-highest water level, and station SW254.5 (Satkhira Khal) in Satkhira Sadar has the third-highest water level for the return period of 100 years. A flood inundation map was prepared using the EV-I method’s 10-year return period value. The Analytic Hierarchy Process (AHP) was used to demonstrate the polders’ vulnerability depending on several factors. Overall, polder15 (Ghubra, Satkhira) is the most vulnerable polder, while polder 33 and polder 32 respectively are the second and third most vulnerable polders for flooding, both located in the Dacope region.
... Thus, any deluge of rainfall from these systems was exacerbated by human factors that led to flash flooding, mudslides, infrastructure collapse, etc. For example, rural-urban migration has led to illegal infrastructure developments, more sewer demands or the blocking of drainage systems and riverbank farming, especially in wetlands or on unstable platforms . ...
Every year, cut-off low (COL) pressure systems produce severe weather conditions and heavy rainfall, often leading to flooding, devastation and disruption of socio-economic activities in South Africa. COLs are defined as cold-cored synoptic-scale mid-tropospheric low-pressure systems which occur in the mid-latitudes and cause persistent heavy rainfall. As they occur throughout the year, these weather systems are important rainfall producing systems that are also associated with extreme cold conditions and snowfalls. An in-depth review of COLs is critical due to their high impacts which affect some parts of the country regularly, affecting lives and livelihoods. Here, we provide a comprehensive review of the literature on COLs over the South African domain, whilst also comparing them with their Southern Hemisphere counterparts occurring in South America and Australia. We focus on the occurrence, development, propagation, dynamical processes and impacts of COLs on society and the environment. We also seek to understand stratospheric–tropospheric exchanges resulting from tropopause folding during the occurrence of COLs. Sometimes, COLs may extend to the surface, creating conditions conducive to extreme rainfall and high floods over South Africa, especially when impinged on the coastal escarpment. The slow propagation of COLs appears to be largely modulated by a quasi-stationary high-pressure system downstream acting as a blocking system. We also reviewed two severe COL events that occurred over the south and east coasts and found that in both cases, interactions of the low-level flow with the escarpment enhanced lifting and deep convection. It was also determined from the literature that several numerical weather prediction models struggle with placement and amounts of rainfall associated with COLs, both near the coast and on the interior plateau. Our study provides the single most comprehensive treatise that deals with COL characteristics affecting the South African domain.
Globally, the frequency and intensity of extreme weather events including flash floods, rising sea levels, and storms is increasing. Poorly planned informal settlements have become more vulnerable. In most regions, infrastructure to cope and protect the vulnerable from such impacts is inadequate. This article aimed to elucidate the main issues faced by South Africa in terms of flood forecasting as well as present an innovative method to assess exposure to floods. A qualitative approach was utilized to gather data during interviews with community leaders and residents of Quarry Road informal settlement. A flood hazard index was developed in a GIS environment. Distance from rivers was calculated, and rainfall intensity and water table level were estimated from metrological measurements, groundwater logging data, and SAR data. A spatial analysis evaluated each grid-point on every parameter and according to the local conditions and each point was assigned values on a scale between 2 and 10. The findings revealed areas most prone to floods in the settlement and the need for a comprehensive post-flood damage database meant for validation purposes and calibrating future prediction models.
Climate change and air pollution are two interconnected global challenges that have profound impacts on human health. In Africa, a continent known for its rich biodiversity and diverse ecosystems, the adverse effects of climate change and air pollution are particularly concerning. This review study examines the implications of air pollution and climate change for human health and well-being in Africa. It explores the intersection of these two factors and their impact on various health outcomes, including cardiovascular disease, respiratory disorders, mental health, and vulnerable populations such as children and the elderly. The study highlights the disproportionate effects of air pollution on vulnerable groups and emphasizes the need for targeted interventions and policies to protect their health. Furthermore, it discusses the role of climate change in exacerbating air pollution and the potential long-term consequences for public health in Africa. The review also addresses the importance of considering temperature and precipitation changes as modifiers of the health effects of air pollution. By synthesizing existing research, this study aims to shed light on complex relationships and highlight the key findings, knowledge gaps, and potential solutions for mitigating the impacts of climate change and air pollution on human health in the region. The insights gained from this review can inform evidence-based policies and interventions to mitigate the adverse effects on human health and promote sustainable development in Africa.
Coastal regions are vital to numerous local economies and the national development of countries globally, including South Africa, due to their significant contributions to job creation, marine transportation, offshore drilling, resource extraction, fish cultivation, recreation and tourism. Despite these contributions to the coastal regions, the coastal communities are threatened by climate change in the form of sea level rise, floods, pollution, coastal erosion, changes to shorelines, extensive damage to critical infrastructure and destruction of coastal livelihoods. While these threats are increasingly hard to overlook, many governments and local administrators, including South Africa, have yet to prepare or implement strategies to meet these menaces adequately. Using mixed method approach of qualitative and quantitative, and extensive literature reviews, this paper explores the consequences of climate change on coastal livelihoods in South Africa. Our findings established that the country's coastal areas are under severe threats with high risks of submergence of floods, saltwater intrusion into surface and groundwater, increased erosion and overwhelmingly negative social and economic repercussions. This paper recommends a higher sense of urgency in addressing climate change threats and a much stronger implementation framework in climate change governance in the country, especially in the coastal zones.
Widespread coral bleaching was observed over the Great Barrier Reef, Australia, the world’s largest coral reef during the 2021–2022 La Niña. This raised concerns that background global warming may have crossed a critical threshold causing thermal stress to corals during a climate state historically associated with increased cloud cover, rainfall and cooler summer water temperatures. Here we present an analysis of recent summer La Niña events focused on their synoptic meteorology and corresponding water temperatures over the Great Barrier Reef. Results show that the 2021–2022 summer La Niña caused accumulated coral heat stress to exceed previous La Niña conditions by 2.5 times. We find that weather patterns that favoured the build-up of heat in water overlying the Great Barrier Reef during the 2021–2022 summer were likely the result of repositioning of planetary scale atmospheric longwaves. This insight provides an additional means to predict potential future atmospheric conditions that increase the risk of extremely high water temperatures and coral bleaching in the Great Barrier Reef.