scholarly journals Geographical Variability of Drought in Northern South Africa

2017 ◽  
Vol 9 (1) ◽  
pp. 53
Author(s):  
Tibangayuka A Kabanda
Keyword(s):  
South Africa ◽  
Seasonal Rainfall ◽  
Dense Network ◽  
Rainfall Characteristics ◽  
Rainfall Season ◽  
Geographical Variability ◽  
Dry Spells ◽  
Source Data ◽  
Precipitation Indices ◽  
Drought Occurrence

This study focuses on the geographical variation of drought in northern South Africa (hereafter NSA). It assesses seasonal rainfall characteristics to determine drought occurrence and persistence in NSA. Seasonal rainfall data for the period 1960-2009 is used and was obtained from the South Africa Weather Service (SAWS). Rainfall stations in NSA are well distributed, forming a dense network of point-source data samples. Standardised Precipitation Indices (SPIs) are employed to detect drought occurrence and intensity at different locations. Analysis of SPIs with respect to time suggests that the severity of drought results from the accumulation of consecutive dry spells within a rainfall season and sometimes even consecutive dry rainfall seasons. It also shows the intensity and frequency of drought has increased in recent years.  The trend towards worsening drought conditions has significant socioeconomic implications for the region and other areas with similar geographical settings.

scholarly journals Forecasting seasonal rainfall characteristics and onset months over South Africa

2018 ◽  
Vol 38 ◽  
pp. e889-e900 ◽  
Author(s):  
Steven Phakula ◽  
Willem A. Landman ◽  
Asmerom F. Beraki
Keyword(s):  
South Africa ◽  
Seasonal Rainfall ◽  
Rainfall Characteristics

scholarly journals Spatial and temporal analysis of the mid-summer dry spells for the summer rainfall region of South Africa

Water SA ◽  
2021 ◽  
Vol 47 (1 January) ◽  
Author(s):  
MG Mengistu ◽  
C Olivier ◽  
JO Botai ◽  
AM Adeola ◽  
S Daniel
Keyword(s):  
South Africa ◽  
Markov Chain ◽  
Crop Yields ◽  
Summer Rainfall ◽  
Seasonal Rainfall ◽  
Chain Model ◽  
Summer Period ◽  
Dry Spells ◽  
Dry Spell ◽  
Rainfall Region

South Africa is frequently subjected to severe droughts and dry spells during the rainy season. As such, rainfall is one of the most significant factors limiting dryland crop production in South Africa. The mid-summer period is particularly important for agriculture since a lack of rain during this period negatively affects crop yields. Dry spell frequency analyses are used to investigate the impacts of sub-seasonal rainfall variability on crop yield, since seasonal rainfall totals alone do not explain the relationship between rainfall and crop yields. This study investigated the spatial and temporal occurrences of the mid-summer dry spells based on magnitude, length and time of occurrence in the major maize growing areas of the summer rainfall region of South Africa. Three thresholds of 5 mm, 10 mm, and 15 mm total rainfall for a pentad were used for the analysis of dry spells.  Dry spell analysis showed that dry pentads occur during mid-summer with differing intensity, duration and frequency across the summer rainfall region. Annual frequency of dry pentads for the mid-summer period ranged between 0 and 4 pentads for the 5 mm threshold and 1 to 7 for the 10 mm and 15 mm thresholds.  The non-parametric Mann-Kendall trend analysis of the dry pentads indicates that there is no significant trend in the frequency of dry spells at a 95% confidence level. The initial and conditional probabilities of getting a dry spell using the Markov chain model also showed that there is a 32% to 80% probability that a single pentad will be dry using the 15 mm threshold. There is a 5% to 48% probability of experiencing two consecutive dry pentads and 1% to 29% probability of getting three consecutive dry pentads. The duration and intensity of dry spells, as well as the Markov chain probabilities, showed a decrease in dry spells from west to east of the maize-growing areas of the summer rainfall region of South Africa.

scholarly journals Air quality indicators from the Environmental Performance Index: potential use and limitations in South Africa

2017 ◽  
Vol 27 (1) ◽  
Author(s):  
RM Garland ◽  
M Naidoo ◽  
B Sibiya ◽  
R Oosthuizen
Keyword(s):  
South Africa ◽  
Air Quality ◽  
Quality Indicators ◽  
Environmental Performance ◽  
Ambient Air ◽  
Ambient Air Quality ◽  
Environmental Performance Index ◽  
Time Period ◽  
Source Data ◽  
Potential Use

In responding to deteriorating air quality, many countries, including South Africa, have implemented national programmes that aim to manage and regulate ambient air quality, and the emissions of air pollutants. One aspect within these management strategies is effective communication to stakeholders, including the general public, with regard to the state and trend of ambient air quality in South Africa. Currently, information on ambient air quality is communicated through ambient mass concentration values, as well as number of exceedances of South African National Ambient Standards. However, these do not directly communicate the potential impact on human health and the ecosystem. To this end, the use of air quality indicators is seen as a potential way to achieve communication to stakeholders in a simplified, yet scientifically defensible manner. Air quality indicators and their source data from the Environmental Performance Index (EPI) were interrogated to understand their potential use in South Africa. An assessment of four air quality indicators, together with their source data, showed improvements in air quality over the time period studied, though the input data do have uncertainties. The source data for the PM indicators, which came from a global dataset, underestimated the annual PM2.5 concentrations in the Highveld Priority Area and Vaal Triangle Airshed Priority Area over the time period studied (2009-2014) by ~3.7 times. This highlights a key limitation of national-scale indicators and input data, that while the data used by the EPI are a well-thought out estimate of a country’s air quality profile, they remain a generalised estimate. The assumptions and uncertainty inherent in such an ambitious global-wide attempt make the estimates inaccurate for countries without proper emissions tracking and accounting and few monitoring stations, such as South Africa. Thus, the inputs and resultant indicators should be used with caution until such a time that local and ground-truthed data and inputs can be utilised.

scholarly journals Projected effects of 1.5 °C and 2 °C global warming levels on the intra-seasonal rainfall characteristics over the Greater Horn of Africa

2020 ◽  
Vol 15 (3) ◽  
pp. 034037 ◽  
Author(s):  
Masilin Gudoshava ◽  
Herbert O Misiani ◽  
Zewdu T Segele ◽  
Suman Jain ◽  
Jully O Ouma ◽  
...  
Keyword(s):  
Global Warming ◽  
Seasonal Rainfall ◽  
Horn Of Africa ◽  
Rainfall Characteristics ◽  
Greater Horn Of Africa

scholarly journals Accurate Quantification of Seasonal Rainfall and Associated Climate–Wildfire Relationships

2010 ◽  
Vol 49 (12) ◽  
pp. 2559-2573 ◽  
Author(s):  
Matthew G. Slocum ◽  
William J. Platt ◽  
Brian Beckage ◽  
Steve L. Orzell ◽  
Wayne Taylor
Keyword(s):  
Daily Rainfall ◽  
Seasonal Rainfall ◽  
Wet Season ◽  
Rainfall Characteristics ◽  
Central Florida ◽  
South Central ◽  
Multiple Regression Technique ◽  
Precise Quantification ◽  
Rainfall Anomalies ◽  
Force Range

Abstract Wildfires are often governed by rapid changes in seasonal rainfall. Therefore, measuring seasonal rainfall on a temporally finescale should facilitate the prediction of wildfire regimes. To explore this hypothesis, daily rainfall data over a 58-yr period (1950–2007) in south-central Florida were transformed into cumulative rainfall anomalies (CRAs). This transformation allowed precise estimation of onset dates and durations of the dry and wet seasons, as well as a number of other variables characterizing seasonal rainfall. These variables were compared with parameters that describe ENSO and a wildfire regime in the region (at the Avon Park Air Force Range). Onset dates and durations were found to be highly variable among years, with standard deviations ranging from 27 to 41 days. Rainfall during the two seasons was distinctive, with the dry season having half as much as the wet season despite being nearly 2 times as long. The precise quantification of seasonal rainfall led to strong statistical models describing linkages between climate and wildfires: a multiple-regression technique relating the area burned with the seasonal rainfall characteristics had an of 0.61, and a similar analysis examining the number of wildfires had an of 0.56. Moreover, the CRA approach was effective in outlining how seasonal rainfall was associated with ENSO, particularly during the strongest and most unusual events (e.g., El Niño of 1997/98). Overall, the results presented here show that using CRAs helped to define the linkages among seasonality, ENSO, and wildfires in south-central Florida, and they suggest that this approach can be used in other fire-prone ecosystems.

scholarly journals Perceptions of Climate Change and Drivers of Insect Pest Outbreaks in Vegetable Crops in Limpopo Province of South Africa

Climate ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 27 ◽  
Author(s):  
Mutondwa Masindi Phophi ◽  
Paramu Mafongoya ◽  
Shenelle Lottering
Keyword(s):  
Climate Change ◽  
South Africa ◽  
Insect Pests ◽  
Climatic Factors ◽  
Smallholder Farmers ◽  
Limpopo Province ◽  
Bivariate Analysis ◽  
Vegetable Production ◽  
Dry Spells ◽  
Pest Outbreaks

Vegetable production is a source of income for smallholder farmers in Limpopo Province, South Africa. Vegetable production is constrained by the negative impacts of climate change and pests. This study assessed farmers’ awareness of climate change, farmers’ knowledge of insect pests and factors that influence insect pests’ prevalence. The data were collected using quantitative and qualitative methods. The data were subjected to descriptive and bivariate analysis. About 84.5% of smallholder farmers were aware of climate change. Late rainfall (24.4%), long dry spells (15%) and increased drought frequency (19.4%) were highlighted as dominant indicators of climate change by farmers. Aphids (22.2%), Bagrada hilaris (12.5%) and Spodoptera frugiperda (10.2%) were the most prevalent insect pests within the Vhembe District. Warmer winters, dry spells and high temperatures were perceived by farmers to influence insect pests’ prevalence within the district. It can be concluded that farmers are aware of climate change and climatic factors influencing pest prevalence within the district. Pest risk maps are needed to improve the preparedness of the government and farmers in controlling insect pests under changing climates.

Dry spells assessment with reference to the maize crop in the Luvuvhu River catchment of South Africa

2016 ◽  
Vol 92 ◽  
pp. 99-111 ◽  
Author(s):  
Teboho Elisa Masupha ◽  
Mokhele Edmond Moeletsi ◽  
Mitsuru Tsubo
Keyword(s):  
South Africa ◽  
Maize Crop ◽  
River Catchment ◽  
Dry Spells
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