Rainfall Variability and Its Impact on Normalized Difference Vegetation Index in Arid and Semi-Arid Lands of Kenya

Abstract

Agriculture in arid and semi-arid lands of Kenya is depends on seasonal characteristics of rainfall. This study seeks to distinguish components of regional climate variability, especially El Niño Southern Oscillation events and their impact on the growing season normalized difference vegetation index (NDVI). Datasets used were: 1) rainfall (1961-2003) and 2) NDVI (1981-2003). Results indicate that climate variability is persistent in the arid and semi-arid lands of Kenya and continues to affect vegetation condition and consequently crop production. Correlation calculations between seasonal NDVI and rainfall shows that the October-December (OND) growing season is more reliable than March-May (MAM) season. Results show that observed biomass trends are not solely explained by rainfall variability but also changes in land cover and land use. Results show that El Niño and La Niña events in southeast Kenya vary in magnitude, both in time and space as is their impact on vegetation; and that variation in El Niño intensity is higher than during La Niña events. It is suggested that farmers should be encouraged to increase use of farm input in their agricultural enterprises during the OND season; particularly when above normal rains are forecast. The close relationship between rainfall and NDVI yield ground for improvement in the prediction of local level rainfall. Effective dissemination of this information to stakeholders will go along way to ameliorate the suffering of many households and enable government to plan ahead of a worse season. This would greatly reduce the vulnerability of livelihoods to climate related disasters by improving their management

The influence of El Niño–Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario

“…Therefore, a temporally and spatially extensive understanding of how the ecosystem dynamics in the region will respond to changing climate, and of particular concern to eastern Africa, to the ENSO regimes, is needed. Several studies related the variability in African vegetation to ENSO events (Shisanya et al, 2011;Ivory et al, 2013;Abdi et al, 2016;Detsch et al, 2016). However, the emergence of this relationship has been less of a focus, partly due to our imperfect knowledge of the nature of the future ENSO response to changing climate.…”

“…The arid and semi-arid vegetation consists of species that can tolerate aridity for several months as a result of the exceedingly seasonal precipitation (Bobe, 2006). Agricultural activity also depends on this strong seasonality as it determines the cropping times (Shisanya et al, 2011). Maize, beans, coffee, tea, and wheat are among the important agricultural products of eastern Africa together with fruit products and grasses for livestock (FAOSTAT, 2016).…”

Forecasting Regional Sugarcane Yield Based on Time Integral and Spatial Aggregation of MODIS NDVI

“…The topography influences the agro-ecological zones receiving an average of 1,400 mm and 1,800 mm of rainfall in the sub humid and humid zones, respectively [24]. Rainfall in this area is bimodal [25] with a long rain season between March and July, with planting in March for food crops and April for sugarcane; and a short rain season in September to December with planting in September for all crops [26]. This variation in rainfall distribution influences an intensified cropping system with crop diversification and rotation of food crops and sugarcane age.…”

Farmer portfolios, strategic diversity management and climate-change adaptation – implications for policy in Vietnam and Kenya

“…The rainfall pattern is divided into 'long rains' in March−May and 'short rains' in October−December (Shisanya, Recha, & Anyamba, 2011), with light showers occurring during the remainder of the year (Ovuka & Lindqvist, 2000).…”