Using Google Earth Engine and the Normalized Difference Drought Index (2000–2024) to assess the spatiotemporal drought severity in Kenya's arid and semi-arid landscape

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

Arid and Semi-Arid Lands (ASALs) have seen a surge in extreme climatic events with devastating environmental and livelihood effects. Understanding the dynamics of these extreme events such as drought at the landscape level is essential for anticipatory action among resource-dependent communities in the ASALs. This study utilised Systems Google Earth Engine (GEE) to analyse 24 years of Normalised Difference Drought Index (NDDI) trends in the Narok West landscape of Kenya across six timeframes (2000, 2005, 2010, 2015, 2020 and 2024). Our analysis revealed increasing trends of severe drought conditions (39.7%), moderate drought conditions (1.4%) and decreased drought conditions (2.1%) over the study period. Temporal increase in drought events were observed to be on the rise from 2015 with extreme events most witnessed in 2020. This weather variability, which may primarily be due to climate change, is expected to result in a rise in the frequency and severity of drought and rainfall periods. This could have a detrimental effect on water quality and quantity, public and ecosystem health, mental health and wellness, peace and protection, and rangeland ecology. For future drought scenarios using Earth Observation Systems (EOS) and GEE, mainly NDDI, our study adds to the body of research that could help with methodological and empirical studies as well as corrective actions. In order to adapt to and manage the effects of a changing climate, these scenarios necessitate interdisciplinary community and landscape strategies. There is need for the community to develop a more comprehensive understanding of the impacts of climate change and the need to plan the sustainable management of water resources.