2025 Volume 16 Issue 1 Pages 89-96
Extreme weather events in developing countries can cause economic consequences, livelihood losses, and increased financial and societal costs. Identifying these events is often accomplished through trend analysis of historical climatic and hydrologic data. This study focused on the Diamphwe River basin in central Malawi. The Diamphwe River basin is a vital region supporting wetlands, ecosystems, agriculture, and water supplies, as well as irrigation for winter vegetable cropping for the Dedza and Lilongwe districts. Over 90 percent of local households earn their livelihood through rain-fed reliant farming. Long-term hydrologic trends were analyzed for the region, which is essential for managing and improving its agricultural productivity. Mann-Kendall and Pettit trend tests were conducted using 1975 to 2010 rainfall and river discharge data generated by R software and XLSTAT. The research revealed long-term trends of decreasing rainfall and river discharge, with 1988 as a transition year for the decreasing trends of the parameters in the basin. We also found that there was trend consistency within each month. Both rainy season and dry season months showed decreasing within months trends of the two parameters. Further, the river discharge fluctuation was significant in November and December, when the dry season changes to the rainy season, and in April, when the rainy season changes to the dry season. To sustain rainfed agriculture and introduce irrigated agriculture, it is suggested that water use planning should be based on the assumption that rainfall and river discharge will gradually decrease in/over what time frame? And that river flow fluctuations will become more significant and impactful in November, December, and April.
