Spatio-temporal temperature trends and extreme hydro-climatic events in southern Zimbabwe

Abstract

Atmospheric warming and extreme weather events have increasingly become major contemporary issues of global concern, yet relatively few studies have investigated recent decadal-scale climate change and variability in Zimbabwe. This study investigates spatiotemporal temperature and extreme weather events in Mzingwane catchment of southern Zimbabwe for the period 1967–2015. This is achieved through using the Non-parametric Modified Mann-Kendal trend test, while magnitudes of trends are estimated using Sen’s slope estimator. Temporal and spatial trends for extreme dryness and wetness are established by using the Standard Precipitation and Evapotranspiration Index. The results for annual anomalies show a strong positive anomaly (.44 °C warmer) at all five stations for the summer months, while winter months recorded cool anomaly averaging −.28 °C. Trends in annual T_max significantly increased (p < .05) at an average of .16 °C decade⁻¹ at four stations, but excluding Matopos, which decreased significantly at .29 °C decade⁻¹. The mean T_max for the period 1897–1904 was .7 and 1.7 °C cooler than the reference average and 2000–2015 average respectively, while historic T_min is .3 and 2.1 °C cooler. Results of extreme events indicate a significant increase (p < .05) in the occurrence of extreme dry periods since the 1980s. The findings are important for developing appropriate sustainable and adaptive strategies as climate changes.

Keywords:

• Climate warming
• temperature trends
• extreme dryness
• extreme wetness
• SPEI