Assessing Temporal Drought Severity in Kenya's Arid And Semi-Arid Landscape Using Google Earth Engine and the Normalized Difference Drought Index

Brian Marvis Waswala-Olewe , George Paul Omondi, Paul Waswa Webala, Romulus Abila

Arid and Semi-Arid Lands have witnessed a surge in extreme climatic events with devastating environmental and livelihood effects. Understanding the dynamics of these extreme events, including drought, is essential for anticipatory action among resource-dependent communities. This study utilised Earth Observatory Systems and Google Earth Engine to analyse 24 years of Normalised Difference Drought Index trends in the Narok West landscape of Kenya across six timeframes (2000, 2005, 2010, 2015, 2020, and 2024). It revealed Normalised Difference Drought Index ranged from -0.489 (April 2000) to 0.469 (August 2005). Additionally, it established that during June-July-August dry seasons, there was an increase in proportionate area under severe drought from 11% in 2000 to 24% in 2024 (average 19.17%, SD: 8.43%); and a decrease in proportionate area under non-drought (good conditions) at 57.5% in 2000 to 40.5% in 2024 (average 40.5%, SD: 7.43%) respectively. Temporal increase in drought events was observed to be increasing from 2015, with extremes witnessed in 2020. Moreover, we established season dry season rainfall averages 147.2 mm (95% CI:100.7 – 193.8) and is decreasing at a rate of 1.25 mm annually. It is anticipated that frequency and severity of drought across the landscape might increase due to weather variability, predominantly attributed to climate change. The increase could have a detrimental effect on water quality and quantity, public and ecosystem health, mental health and wellness, peace and protection, and rangeland ecology. Our study contributes to the body of research on future drought scenarios, which could assist with methodological and empirical studies and corrective actions. To adapt to and manage the effects of changing climate, these scenarios necessitate interdisciplinary community and landscape strategies, including the need for communities to develop comprehensive understanding of the impacts of climate change and plan for the sustainable management of water resources.