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Cyclones are some of the most devastating natural disasters that cause major losses of life and property. A few months after Cyclone Idai swept through Beira, Mozambique between 4 and 20 March 2019. An analysis is presented on the impacts of this disaster by assessing the extent of the floods. This study employed Sentinel-2 imagery and remote sensing techniques including a threshold analysis and an object‑based image analysis (OBIA) approach. Water and non-water land covers were established by using a Modified Normalized Difference Water Index (MNDWI), while the classification approach assessed three land covers. These assessments were done on four dates: (1) 31 January (before), (2) 25 February 20 (before), (3) 12 March (during) and (4) 16 April (after). Accuracies ranging from 74% to 90% were attained. The OBIA approach showed that 61% of the study area was affected by floods, while the threshold approach showed that 55% of the area was flooded. Areas with low elevation and close to the coast were more effected by the floods. After the cyclone, the area under water reduced by more than 20%. The results here could be useful for developing early warning systems, risk assessment, establishing damage and developing natural hazard policies. [ABSTRACT FROM AUTHOR]

This study reveals rainfall variability and trends in the African continent using TAMSAT data from 1983 to 2020. In the study, a Mann–Kendall (MK) test and Sen's slope estimator were used to analyze rainfall trends and their magnitude, respectively, under monthly, seasonal, and annual timeframes as an indication of climate change using different natural and geographical contexts (i.e., sub-regions, climate zones, major river basins, and countries). The study finds that the highest annual rainfall trends were recorded in Rwanda (11.97 mm/year), the Gulf of Guinea (river basin 8.71 mm/year), the tropical rainforest climate zone (8.21 mm/year), and the Central African region (6.84 mm/year), while Mozambique (−0.437 mm/year), the subtropical northern desert (0.80 mm/year), the west coast river basin of South Africa (−0.360 mm/year), and the Northern Africa region (1.07 mm/year) show the lowest annual rainfall trends. There is a statistically significant increase in the rainfall in the countries of Africa's northern and central regions, while there is no statistically significant change in the countries of the southern and eastern regions. In terms of climate zones, in the tropical northern desert climates, tropical northern peninsulas, and tropical grasslands, there is a significant increase in rainfall over the entire timeframe of the month, season, and year. This implies that increased rainfall will have a positive effect on the food security of the countries in those climatic zones. Since a large percentage of Africa's agriculture is based only on rainfall (i.e., rain-fed agriculture), increasing trends in rainfall can assist climate resilience and adaptation, while declining rainfall trends can badly affect it. This information can be crucial for decision-makers concerned with effective crop planning and water resource management. The rainfall variability and trend analysis of this study provide important information to decision-makers that need to effectively mitigate drought and flood risk. [ABSTRACT FROM AUTHOR]