Climate change impact on water availability in the olifants catchment (South Africa) with potential adaptation strategies

Increasing population and economic growth has intensified water supply pressure on the Olifants River Basin causing it to become water-stressed. Climate change is expected to aggravate existing water supply challenges in the basin if urgent interventions are not implemented. This study evaluates the impacts of climate change on water availability and demand in the Olifants River Basin of South Africa, and assesses to what extent a combination of management strategies can mitigate current and longer term impacts using the Water Evaluation and Planning (WEAP) model. The results demonstrated by the two projected climate change scenarios (RCP4.5 and RCP8.5) showed a rise in temperature of approximately 1 °C–4 °C, and a decrease in precipitation of 5%–30%, as compared to the baseline climate of 1976–2005. Results also showed that pressure on water supply due to increased economic activities and a decline in streamflow will increase unmet water demand by 58% and 80% for the mid and end century periods respectively. Results further revealed that the combination of management measures proposed by decision makers is expected to decrease future unmet water demand from 1006MCM to 398MCM, 1205MCM to 872MCM and 1251MCM to 940MCM for reference, RCP4.5 and RCP 8.5 scenario respectively. The study therefore concludes that the combination of management strategies provides a much better and more efficient solution to water scarcity issues in the basin, compared to a reliance on a single strategy.The National Research Foundation – The World Academy of Sciences (NRF-TWAS).http://www.elsevier.com/locate/pce2021-09-15hj2021Geography, Geoinformatics and Meteorolog

A yield gap analysis to assess vulnerability of commercial sugarcane to climatic extremes in southern Africa

Sugarcane yields have steadily declined across southern Africa for the past 25 years and, despite research into the causes, there has been limited progress in addressing these trends. This study developed a methodology of assessing yield declines and performed a yield gap analysis to assess and develop recommendations to assist in combating yield declines and offering potential safeguards for the sugarcane industry against climatic extremes. Mill areas from South Africa, eSwatini, Malawi and Tanzania were selected, providing a diversity of regional hydroclimatic conditions and sugarcane agronomic management approaches. Using the AquaCrop crop model, maximum potential yields and yield gaps were simulated based on observed climate and yield data spanning 25 years. Results show that yields are declining for the mill areas in South Africa, Malawi and Tanzania, resulting in increased yield gaps, whilst yields are stagnant in eSwatini resulting in relatively fixed yield gaps. Yield gaps remained high across all six mill areas, suggesting that they remain vulnerable and exposed to climatic extremes. Modelling results suggest that these yield trends, including yield gaps, are primarily attributed to existing crop management approaches as opposed to the climatic regimes in these areas. Recommendations include several solutions that could result in an immediate response and reduce yield gaps while increasing harvestable yields. Such measures include increasing technology transfer and agronomic management education to small-scale outgrowers, adopting drought-resistant, high-yielding sugarcane varieties, contouring and mulching, improving soil structural properties and minimizing in-field traffic. The study concludes that if sugarcane growers are to withstand the effects of extreme climatic events, they have to consider shifting crop management approaches and be proactively included in related research.http://www.sciencedirect.com/journal/journal-of-agriculture-and-food-researchGeography, Geoinformatics and Meteorolog

An assessment of the vulnerability and adaptation potential of sugarcane production to water stress, southern Africa

DATA AVAILABILITY : Data will be made available on request.The high spatial variability of precipitation, heightened frequency of droughts and concomitant increases in exposure to water stress across southern Africa due to climate change, presents significant challenges for sugarcane production and the regional sugarcane production value chain. While production has intensified in the past few decades, yields have declined due to increased climatic variability and agronomic management approaches. Increased precipitation variability has enhanced sugarcane vulnerability to water stress and is likely to negatively affect yields. Combining crop simulations and relationships between sugarcane water use and observed rainfall, we introduce a crop productivity ratio (CPR) which assesses sugarcane water stress for six sugarcane mills across southern Africa. The CPR and simulation results were used to assess the adaptation potential or ‘space’ for mill areas that have varying rates of exposure and abilities to adapt to water stress. Simulation results were used to determine the long-term adaption potential of mill areas and to surmise the causes of yield declines. The results were used to offer recommendations to reduce vulnerabilities and enhance adaptation to water stress. We conclude that the amplification of inter-annual precipitation variability will enhance the exposure of sugarcane to water stress and require adaptation interventions. Adapting to external shocks is a multifaceted exercise that requires a holistic approach that includes every aspect of the sugarcane value chain.The University of KwaZulu-Natal's Centre for Water Resources Research (CWRR).http://www.sciencedirect.com/journal/journal-of-agriculture-and-food-researchhj2024Geography, Geoinformatics and MeteorologySDG-02:Zero HungerSDG-13:Climate actio

Agricultural perspectives on the 2015-2018 Western Cape drought, South Africa : characteristics and spatial variability in the core wheat growing regions

Between 2015 and 2018, the Western Cape Province of South Africa experienced a multi-year severe drought, which negatively impacted major economic sectors. The province serves as an important producer of wheat in South Africa among other agricultural commodities. This study aims to analyze the 2015-2018 drought and its impacts on wheat production in the winter rainfall region of the Western Cape, South Africa. The central focus is to place the drought in both a historical and future context while emphasising the differences between the two core wheat growing regions. We present an analysis of the drought, as well as climate trends computed from weather data sets (1988–2018) from six weather stations across the two core wheat-growing. We first present a meteorological drought analysis of mean annual and seasonal rainfall and temperatures, subsequently providing an agricultural lens by computing Standardised Precipitation and Evapotranspiration Index (SPEI) accumulated over 12- and 36-month timescales, self-calibrated Palmer Drought Severity Index (sc-PDSI), changes to the start and end of the rainfall season, and their effects on wheat yields. Trend analysis was conducted to determine if drought observations form part of the longer-term trends in the region. Finally, we show how the drought varied spatially across the two regions. Results show that between 1988 and 2018, the wheat growing areas of the Western Cape experienced persistent drought with high spatial-temporal variability. The 2015-2018 drought, however, was the most severe experienced in the 30-year study period at five of the six stations. These results are consistent with conditions that can be expected under future climate change. Moreover, results can be useful for the development of early warning systems since they place the drought in the context of past drought conditions.The Agriculture Research Council's Professional Development Programhttps://www.elsevier.com/locate/agrformethj2022Geography, Geoinformatics and Meteorolog

Integrated assessment of the influence of climate change on current and future intra-annual water availability in the Vaal River catchment

Increasing water demand due to population growth, economic expansion and the need for development puts a strain on the supply capacity of the Vaal River catchment in South Africa. Climate change presents additional challenges in the catchment which supports the country's economic hub, more than 30% of its population and over 70% of its maize production. This study evaluates the influence of climate change on current and future intra-annual water availability and demand using a multi-tiered approach where climate scenarios, hydrological modelling and socio-economic considerations were applied. Results shows exacerbated water supply challenges for the future. Temperature increases of between 0.07 and 5 °C and precipitation reductions ranging from 0.4 to 30% for Representative Concentration Pathways (RCPs) 4.5 and 8.5, respectively, are also predicted by the end of the century. The highest monthly average streamflow reductions (8–10%) are predicted for the summer months beyond 2040. Water Evaluation and Planning (WEAP) simulations project an increase in future water requirements, gaps in future water assurance and highlight limitations in existing management strategies. The study recommends a combination of adaptation plans, climatic/non-climatic stressor monitoring, wastewater-reuse, conservation, demand management and inter-basin transfers to reduce future uncertainty in monthly water sustainability.https://iwaponline.com/jwcchj2021Geography, Geoinformatics and Meteorolog

Temperature and relative humidity trends in the northernmost region of South Africa, 1950–2016

The northernmost Limpopo Province is located in one of the warmest regions of South Africa, where the agricultural sector is prone to heat stress. The aim of this study was to explore air temperature and relative humidity trends for the region, which have implications for agricultural adaptation and management (amongst other sectors). In particular, we investigated seasonal, annual and decadal scale air temperature and relative humidity changes for the period 1950–2016. Positive temperature trends were recorded for this period, averaging +0.02 °C/year, with the strongest changes observed in mean maximum summer temperatures (+0.03 °C/year). Interannual temperature variability also increased over time, especially for the period 2010–2016, which presents probability densities of <50% for minimum temperatures. Positive relative humidity trends (+0.06%/year) were also recorded for the period 1980– 2016, but proved to be the least predictable weather parameter, with probability densities of <0.5% across seasons for the study period. Considering the substantial interannual variability in temperature and relative humidity, there is clear increased risk for the agricultural sector, particularly for small-scale farmers who generally have limited capacity to adapt. Climate science focusing on the southern African region should continue to establish the impact of climate change and variability on specific small-scale farming systems and enterprises, with recommendations for strategic adaptation based on up-to-date evidence. SIGNIFICANCE : • Heat indices have increased, and variability in temperature and relative humidity has substantially increased over recent decades. • Changes in air temperature and relative humidity have direct and/or indirect negative effects on sectors such as agriculture, leading to reduced productivity. • The small-scale farming sector, which contributes significantly to national food security in developing countries, is the production system most exposed and vulnerable to observed changes/extremes in temperature and relative humidity. • There is an urgent need to build capacity of small-scale farmers for appropriate adaptation to observed changes in climate based on up-to-date evidence.Open Society Foundationhttp://www.sajs.co.zahj2021Geography, Geoinformatics and Meteorolog

Perceived impacts of climate change on rural poultry production : a case study in Limpopo Province, South Africa

Rural farming households in developing countries frequently contend with multiple challenges, including a lack of resources, food insecurity, and poverty. Climate change threatens to compound existing challenges, particularly in such rural subsistence economies with limited adaptive capacity. We aim to establish farmers' perspectives on likely impacts of climate change on their rural poultry production in northern South Africa. A baseline questionnaire-based study was conducted across 106 households in the town of Musina, South Africa. Most households lacked reliable and adequate sources of income and had, for example, days when they had to skip meals as a coping strategy. With such poverty, coupled with poor access to scientific information on agricultural production, these farmers typically have limited capacity to adapt to shocks such as climate variability and change. Farmers reported a reduction in poultry productivity in recent years, coinciding with increased ambient temperatures. There are concerns that recent and ongoing warming trends will have negative impacts on the future growth and wellbeing of birds. However, the farmers in our study perceived their poultry as hardy and well adapted to survive any future climatic changes and may be uninclined to take adaptive action at this stage.The Global Change Institute, University of the Witwatersrand Johannesburg.http://www.tandfonline.com/toc/tcld20hj2023Geography, Geoinformatics and Meteorolog

Using SPI and SPEI for baseline probabilities and seasonal drought prediction in two agricultural regions of the Western Cape, South Africa

Drought is one of the most hazardous natural disasters in terms of the number of people directly affected. An important characteristic of drought is the prolonged absence of rainfall relative to the long-term average. The intrinsic persistence of drought conditions continuing from one month to the next can be utilized for drought monitoring and early warning systems. This study sought to better understand drought probabilities and baselines for two agriculturally important rainfall regions in the Western Cape, South Africa – one with a distinct rainfall season and one which receives year-round rainfall. The drought indices, Standardised Precipitation and Evapotranspiration Index (SPEI) and Standardised Precipitation Index (SPI), were assessed to obtain predictive information and establish a set of baseline probabilities for drought. Two sets of synthetic time-series data were used (one where seasonality was retained and one where seasonality was removed), along with observed data of monthly rainfall and minimum and maximum temperature. Based on the inherent persistence characteristics, autocorrelation was used to obtain a probability density function of the future state of the various SPI start and lead times. Optimal persistence was also established. The validity of the methodology was then examined by application to the recent Cape Town drought (2015–2018). Results showed potential for this methodology to be applied in drought early warning systems and decision support tools for the province.https://www.watersa.netGeography, Geoinformatics and Meteorolog

Editorial : extreme events in the developing world

This Research Topic “Extreme Events in the Developing World” showcases a selection of articles that develop our knowledge of extreme events in the developing world. Papers range from those presenting recent evidence for and future likelihood of changes in the occurrence and exposure to extreme events, together with examples of the impacts of extreme events in a variety of sectors. Papers also consider the range of climate services responses to this challenge, highlighting the need for new types of weather and climate information, new methods of producing and communicating that information in order to reduce risk, as well as providing some key examples of success stories, with a particular focus on Africa. Our intention here is to balance some of the bad news with what might work, and how we might learn from such examples.UK Natural Environment Research Council (NERC); UK Government’s Department for International Development (DFID); UKRI Global Challenges Research Fund Africa-SWIFT project; NASA GPM project.https://www.frontiersin.org/journals/climatedm2022Geography, Geoinformatics and Meteorolog

Agricultural resilience and adaptive capacity during severe drought in the Western Cape, South Africa

Meeting the needs of multiple users and uses of freshwater resources is becoming progressively challenging. The response to the 2015–2018 Western Cape drought in South Africa offers lessons for both commercial crop growers and policymakers to enhance resilience. The drought highlights the complex interactions between water supply for urban and agricultural uses. This study employed a mixed-methods approach by combining the five capitals (natural, physical, financial, human, and social) of the sustainable livelihoods framework with semi-structured interviews to assess the impacts of the hydrologic and socio-economic drought on irrigated apple production. Data used for the study included production statistics, dam and water flow, weather data, and interviews. Results highlight a progressive weakening of the natural and physical capital between 2015 and 2018. Human capital in the form of expert consultants together with social capital of networks proved key to mitigating the impact of drought on apple production. The study also found that growers’ adaptive capacity was high as they made use of multiple capitals available to them. This resulted in lower than anticipated impacts on production and in turn stabilized financial capital available to farmers. Lessons from the drought show that building human and social capital can significantly improve the resilience of commercial farms which form part of complex water systems. Urban water-related vulnerabilities and demand are closely interlinked with the vulnerability and adaptive capacity of irrigated agriculture. Thus, policies which facilitate the in-tandem adaptation of these sectors are likely to be most successful in building resilience.The Agricultural Research Council’s Professional Development Program and the International Institute for Applied Systems Analysis.http://link.springer.com/journal/101132024-07-24hj2024Geography, Geoinformatics and MeteorologySDG-13:Climate actio