Citation: Sikhwari, T.; Nethengwe,
N.; Sigauke, C.; Chikoore, H.
Modelling of Extremely High
Rainfall in Limpopo Province of
South Africa. Climate 2022, 10, 33.
https://doi.org/10.3390/cli10030033
Academic Editor: Salvatore Magazù
Received: 24 January 2022
Accepted: 21 February 2022
Published: 28 February 2022
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climate
Article
Modelling of Extremely High Rainfall in Limpopo Province of
South Africa
Thendo Sikhwari
1,†
, Nthaduleni Nethengwe
1
, Caston Sigauke
2,
*
,†
and Hector Chikoore
3
1
Department of Geography and Geo-Information Sciences, School of Environmental Sciences,
University of Venda, Thohoyandou 0950, South Africa; sikhwarimushavhi@gmail.com (T.S.);
nthaduleni.nethengwe@univen.ac.za (N.N.)
2
Department of Mathematical and Computational Sciences, University of Venda, Private Bag X5050,
Thohoyandou 0950, South Africa
3
Unit for Environmental Science and Management, North West University, Vanderbijlpark 1900, South Africa;
32945280@nwu.ac.za
* Correspondence: caston.sigauke@univen.ac.za
† These authors contributed equally to this work.
Abstract: Extreme value theory is a powerful method that is known to provide statistical models
for events rarely observed. This paper presents a modelling framework for the maximum rainfall
data recorded in Limpopo province, South Africa, from 1960 to 2020. Daily and monthly rainfall
data were obtained from the South Africa Weather Service. In this work, the r-largest order statistics
modelling approach is used. Yearly blocks were used in fitting a 61 years’ data set. The parameters
of the developed models were estimated using the maximum likelihood method. After the suitable
model for data was chosen, i.e., GEVD
r=8
, the 50-year return level was estimated as 368 mm, which
means a probability of 0.02 exceeding 368 mm in fifty years in the Thabazimbi area. This study helps
decision-makers in government and non-profit organisations improve preparation strategies and
build resilience in reducing disasters resulting from extreme weather events such as excessive rainfall.
Keywords: extreme value theory; Fréchet class of distribution; maximum rainfall; r-largest
order statistics
1. Introduction
Climate extremes such as floods, droughts and heatwaves have become topical issues
since they have triggered most natural disasters in recent decades that can potentially
affect humans and the natural environment [1]. Climate extreme events are regular across
the globe and impact society in various ways, leading to loss of lives, shortage of food,
failure of crops, famine, mass migration and health issues [2]. The increased number,
frequency and intensity of natural hazards such as floods, heatwaves and hurricanes are
generally attributed to climate change [3–5]. In Africa, impacts of a changing climate
vary significantly by region [6,7]. More than 90% of natural disasters in southern Africa
are related to weather, climate and water. Understanding extreme climate events will
help prepare and formulate mitigation strategies to cope with events associated with
climate change. Modelling and predicting future extreme events become more relevant in
commercial agriculture, to insurance companies, statisticians and meteorologists.
Extreme climate and weather events such as floods, droughts and heatwaves negatively
impact society, environment and resource management in developing countries [6,8,9].
In South Africa, anomalous cut-off lows, tropical cyclones and tropical storms are the major
extreme rainfall producing systems affecting the Limpopo province, while the Botswana
High becomes dominant during heatwaves and drought. Extreme weather events are
common in Limpopo during summertime and often coincide with mature phases of the
El Niño Southern Oscillation. In February 2000, about 700 people lost their lives and
over a million residents were displaced in Mozambique due to flooding associated with
tropical cyclone Eline [10,11]. In recent decades (1980–2015), southern Africa experienced
Climate 2022, 10, 33. https://doi.org/10.3390/cli10030033 https://www.mdpi.com/journal/climate