Production : Abiotic Constraints : Rainfall Variability and Drought

Modeled percentage of failed seasons due to drought in the study areas (Hyman et al. 2008)

Rainfall Variability and Drought

An important consequence of climate change is the increasingly higher frequency of extreme weather events, including frequent flooding and longer drought periods (Intergovernmental Panel on Climate Change 2001, Easterling et al. 2000). To some extent, impacts from the climate variability on crop production can be overcome by improving water and nutrient managements in high-input crop production systems. However, such improved management options require investments that are not readily available for most smallholder farmers in sub-Saharan Africa (SSA), where only less than 5% of agricultural land area is irrigated. Most crop production area in SSA is thus inevitably vulnerable to rainfall variability and drought.

Drought also often spatially coincides with high levels of poverty in major farming systems, especially in South Asia, the Sahel and eastern and southern Africa (Hyman et al. 2008). However, combined with other agro-ecological constraints (e.g., soil degradation) and the physiology of crops (e.g., different yield sensitivity to drought at different stages of crop growth), it is not always straightforward to understand and assess the vulnerability of agricultural production to climate factors alone. For example, low amounts of precipitation do not necessarily lead to drought, nor is drought necessarily associated with low rainfall (Gommes and Petrassi 1996).

To achieve better understanding of the dynamics in crop production systems, HarvestChoice uses the Spatial Evaluation Framework to simulate multidimensional impacts of the rainfall variability and drought on crop production systems, using historical climate records as well as projected future climate data. Site-specifically simulated crop growth and production responses under a range of climatic and management scenarios help identify and measure vulnerability of different crop production systems. This information will be further used to support making a better choice of investments in cropping systems to stabilize production and minimize risks.

References

Intergovernmental Panel on Climate Change 2001: Synthesis Report, Third Assessment Report of the Intergovernmental Panel on Climate Change. New York: Cambridge Univ. Press, 2001.

Easterling, D.R., G.A. Meehl, C. Parmesan, S.A. Changnon, T.R. Karl, and L.O. Mearns. Climate Extremes: Observations, Modeling, and Impacts. Science 289(2000):2068-2074.

Hyman, G., S. Fujisaka, P. Jones, S. Wood, M.C. de Vicente, and J. Dixon. Strategic Approaches to Targeting Technology Generation: Assessing the Coincidence of Poverty and Drought-prone Crop Production. Agricultural Systems 98(2008):50-61.

Gommes, R. and F. Petrassi, "Rainfall Variability and Drought in Sub-Saharan Africa Since 1960," Working Paper No 9, FAO Agrometeorology Series, FAO, 1996.

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