Spatial and inter-seasonal behaviour of rainfall in the Soutpansberg region of South Africa as attributed to the changing climate

Abstract

The inter-seasonal behaviour of rainfall in the Soutpansberg region of South Africa was assessed in relation to changing climate with an attempt to diagnose some of the contributing external factors. Seasonal rainfall data from 1970 to 2009 was characterised for the Soutpansberg using 23 rainfall stations distributed over the mountain range. The normality of rainfall data was quality-controlled using the Pearson correlation coefficient and a double mass curve. Composite rainfall and standardised anomaly index for the region were calculated in order to assess seasonal variability of rainfall. The results showed that the range experienced a decline in seasonal rainfall, from east to west. The North West (NW) part of the region experienced its lowest rainfall in 1985, with a standardised anomaly index (SAI) of −0.94, and its highest rainfall was experienced in 1978, with an SAI of 0.5. The North East (NE) recorded lowest rainfall in 1985 with an SAI of −1, and the highest rainfall was observed in the years ranging from 1977 to 1980 with an SAI of 1. The South East (SE) experienced lowest rainfall in 1985 with a value of −1.25 below the mean, and its highest rainfall (1.25) was experienced in 1976. The study showed that seasonal rainfall in the north-facing slope was lower than the rainfall in the south-facing slope. Trend line analysis indicated that the NW part of the Soutpansberg experienced the most substantial decrease in rainfall. The NW region was followed by the NE, SW, SE and the Central East (CE) respectively in terms of the decline in rainfall. Such behaviour and trends which varies across space and time is a cause for concern in the period of study. This period was characterised by increase in anthropogenic activities, as earlier studies prior to 1970 demonstrated a near stable pattern in terms of the cyclic activity of rainfall.

Assessment of impact of land use change on the wetland in Makhitha village, Limpopo province, South Africa

“…The study area is located within a subtropical climatic region, with high temperatures in summer and low temperatures in winter. The study area has hot summer months, which usually start from September to April, and winter starts from May to August (Kephe, Petja & Kabanda 2016). The lowest temperature experienced is around 10°C in June and July, and the highest temperature is about 34°C in January (WRC 2001).…”

Cortisol metabolites vary with environmental conditions, predation risk, and human shields in a wild primate, Cercopithecus albogularis

“…Populations in the Soutpansberg deal with overnight temperatures much colder than those in lowland or coastal environments (Coleman and Hill, 2014a), but over the coming decades, the Soutpansberg is expected to become hotter and dryer (Kephe et al, 2016), potentially affecting native plant communities and the animals that rely on them. Evidence from other populations of this species that deal with less seasonal variation indicates that reduced food availability is a major predictor of heightened fecal GC metabolite levels (Foerster et al, 2012;Foerster and Monfort, 2010), and fecal cortisol metabolites (FCMs) more specifically (Thompson et al, 2020).…”

“…An absence of rainfall in the dry season (but not in the wet season) was associated with higher FCMs, indicating that water scarcity might be a challenge for these animals. This western Soutpansberg population has had to contend with increasing drought over the past several decades (Kephe et al, 2016),…”

A geomorphodiversity map of the Soutpansberg Range, South Africa

“…The studies covered fields such as biology (Foord et al 2008, Hahn 2010, Taylor et al 2013, Grey et al 2017 climatology (Kabanda 2004, Kabanda, Munyati 2010, Nenwiinia, Kabanda 2013, Kephe et al 2016, ecology (Mostert 2006, Kirchhof et al 2010, Foord et al 2015, and on geology (Berger et al 2003). Kabanda (2004) describes the Soutpansberg range as a complex terrain of ridges with various peaks, separating vast areas of valley systems.…”

“…The topographic setting of the mountain range gives rise to orographic rainfall and wind patterns that create a diversity of microclimates (Berger et al 2003, Kephe et al 2016. The geological substrate and the geomorphological processes create the basis for the weathering activity and the soil formation that create unique abiotic settings (Musila et al 2005).…”