Projections of precipitation and temperature trends in the Breede and Berg River Catchments, South Africa

Abstract

The study assessed historical (2004–2023) and projected (2024–2043) precipitation and temperature trends in the Berg and Breede River Catchments of South Africa's Western Cape Province. Projections were conducted using the MIROC6 model, while the Mann-Kendall trend test and Sen's slope estimator were applied to determine trends. During the 2015–2018 period, 70% of the stations recorded low annual precipitation, ranging from 51.00 to 312.50 mm. Rising temperatures were observed at 80% of the stations, with statistically significant increases of 0.04–0.07 °C per year. Under the SSP2 scenario, 90% of stations exhibited increasing precipitation, with statistically significant increases of 3.97 to 18.06 mm per year at 60% of the stations. Temperature also increased significantly across all stations, by 0.04–0.06 °C per year. In contrast, projected precipitation at all stations under the SSP5 scenario showed a declining trend, with statistically significant decreases of 7.90–20.76 mm per year at 60% of stations, especially during the 2040–2043 period. Temperature is projected to rise significantly at all stations by 0.05 to 0.08 °C per year, exceeding SSP2 by approximately 0.01 to 0.02 °C per year. The study provides empirical evidence required to enhance climate-resilient water management, thus strengthening climate change adaptation in the two catchments.