Observed trends and projections of temperature and precipitation in the Olifants River Catchment in South Africa

Abiodun Morakinyo Adeola; Andries Kruger; Thabo Elias Makgoale; Joel Ondego Botai

doi:10.1371/journal.pone.0271974

Observed trends and projections of temperature and precipitation in the Olifants River Catchment in South Africa

PLoS One. 2022 Aug 9;17(8):e0271974. doi: 10.1371/journal.pone.0271974. eCollection 2022.

Authors

Abiodun Morakinyo Adeola^{1

2

3}, Andries Kruger^{1

3}, Thabo Elias Makgoale¹, Joel Ondego Botai^{1

3

4}

Affiliations

¹ South African Weather Service, Pretoria, South Africa.
² School for Health Systems and Public Health, University of Pretoria, Pretoria, South Africa.
³ Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, South Africa.
⁴ School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Westville Campus, Durban, South Africa.

Abstract

Among the projected effects of climate change, water resources are at the center of the matrix. Certainly, the southern African climate is changing, consequently, localized studies are needed to determine the magnitude of anticipated changes for effective adaptation. Utilizing historical observation data over the Olifants River Catchment, we examined trends in temperature and rainfall for the period 1976-2019. In addition, future climate change projections under the RCP 4.5 and RCP 8.5 scenarios for two time periods of 2036-2065 (near future) and 2066-2095 (far future) were analysed using an ensemble of eight regional climate model (RCA4) simulations of the CORDEX Africa initiative. A modified Mann-Kendall test was used to determine trends and the statistical significance of annual and seasonal rainfall and temperature. The characteristics of extreme dry conditions were assessed by computing the Standardized Precipitation Index (SPI). The results suggest that the catchment has witnessed an increase in temperatures and an overall decline in rainfall, although no significant changes have been detected in the distribution of rainfall over time. Furthermore, the surface temperature is expected to rise significantly, continuing a trend already evident in historical developments. The results further indicate that the minimum temperatures over the Catchment are getting warmer than the maximum temperatures. Seasonally, the minimum temperature warms more frequently in the summer season from December to February (DJF) and the spring season from September to November (SON) than in the winter season from June to August (JJA) and in the autumn season from March to May (MAM). The results of the SPI affirm the persistent drought conditions over the Catchment. In the context of the current global warming, this study provides an insight into the changing characteristics of temperatures and rainfall in a local context. The information in this study can provide policymakers with useful information to help them make informed decisions regarding the Olifants River Catchment and its resources.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Climate Change*
Rivers*
Seasons
South Africa
Temperature

Grants and funding

Partial funding for the background research was received from the South32 mining company. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.