Analysis of Rainfall, Wind Speed and Streamflow Trends and Their Relationships in the Klip River Catchment, Alfred Duma Municipality, South Africa

Abstract

Ladysmith, a town in South Africa's KwaZulu-Natal province, has experienced flooding almost every year since 1884, resulting in temporary water shortages as well as the loss of lives, properties, and businesses. Ladysmith is a major economic, financial, and administrative hub for both the Alfred Duma municipality and the uThukela District Municipality. This study aimed to study the relationships between rainfall, wind speed, and streamflow trends in the Klip River catchment. The monthly, seasonal and annual trends were studied using the Mann-Kendall test. The study's findings revealed both decreasing and increasing trends in all streamflow, wind speed and rainfall. Streamflow and wind speed increased in most months, while rainfall had an equal combination of both increasing and decreasing trends throughout the year. The average annual streamflow decreased at a rate of -1.39 m3/s, rainfall at -3.05 mm, whereas wind speed increased by 3.68 m/s. On a seasonal scale, streamflow showed a decrease in spring and summer, whereas rainfall increased in the same seasons. In contrast, wind speed showed an increasing trend in all seasons. These results could be helpful in the planning and development of sustainable flood mitigation strategies.