Is there evidence to support the rising incidence of drought, and if so, what are the causes and remedies?
Drought predictions and early warning systems depend largely on indirect measures based on satellite tracking of green vegetation and rainfall measures and predictions. Neither method has been tested against long term measurements of actual pasture abundance, or the severity of droughts for livestock and wildlife. How well do these drought predictions perform?
Twenty grassland plots in Amboseli measured each month by ACP since 1975 provide a good test of the accuracy of drought predictions. A study, published in PLoS ONE (download here) in August 28 2015 by David Western, Victor Mose and David Maitumo, concludes that neither satellite imagery nor rainfall measures satisfactorily predict extreme droughts. The grazing pressure by livestock and wildlife is far more important in dictating the shortage of forage and severity of droughts.
The study also shows that pasture shortfalls are increasing in frequency and intensity due to grazing pressure have risen nearly three-fold in the past 35 years. Although rainfall has not fallen significantly, grass production per unit of rainfall has fallen by a third, causing a sharp drop in livestock and wildlife production. The causes are explained by the loss of grazing lands to farms, water diversion and permanent settlement leading to the year-round grazing of pastures.
We conclude that the remedies largely lie with herders through better rangeland governance, herding practices based on traditional migratory movements, and grazing rotation (see Better grazing practices hold key to Kenya drought. SciDev.Net. 5 August 2011). Collaborative grazing practices and land use planning are now the focus of ACC’s conservation work with group ranches in Amboseli and the South Rift.
Just as important, the Amboseli study shows that regular rangeland monitoring such as David Maitumo conducts in Amboseli each month can be conducted simply and rapidly by community resource assessors using simple methods. The information feeds back directly to herding committees, allowing them to take stock of pasture conditions, anticipate extreme droughts and plan their responses