aWhere’s assessment of a 4-country region (Zambia, Zimbabwe, Malawi, Mozambique) in Southern Africa shows alarming trends. December (2019) to February (2020) were dangerously dry in southern Africa. Precipitation / Potential Evapotranspiration (P/PET) was well below the threshold for maize (P/PET>0.80). This will negatively impact farmers who traditionally expect values of P/PET well above 0.80.
P/PET is a powerful index for understanding the conditions conducive for crop production. As Precipitation (P) drops below PET (the evaporative demand of the environment), the result are dry conditions and plants start to wilt. The threshold for maize is 0.8, when P/PET is less than 0.8, maize is likely to fail. Water stress becomes acute as the P/PET ratio drops below 0.7 and below 0.6 the ecology shifts to grassland and then below 0.4 is when desert conditions prevail.
Delivering local observed weather and insights on shifting weather patterns can empower farmer to adapt by shifting to drought tolerant crops (e.g. sorghum, millets) and investing in watershed management and relief irrigation capacity.
Analytics: Understanding Weather Variability
The Coefficient of Variation** (CV) for P/PET is increasing due to extreme daily and seasonal rainfall variability and points to required investments in watershed management. Weather variability due to climate change causes significant disruptions to food security, water availability, and the economy as it brings increased risk to agriculture and adjacent sectors. aWhere analysts highlight coefficient of variation (CV) to describe the extent of weather variability in specific locations. The CV is shown as a percent and as a general rule, any location with a CV of greater than 20% is considered highly variable. By understanding variability, officials can make data-driven decisions to drive new investments in irrigation infrastructure.
Nearly 73% of the population (~57M people) live in areas where the variance in P/PET for the main growing season is greater than 20%. This is the threshold used by crop breeders for when variance is too high for accurate trial data. This variability in rainfall poses a tremendous risk to farmers who over time lose confidence in investing in good agronomic practices. This in turn leads to lower productivity and risk of food insecurity. The map below shows the CV for the rainy season in this region from 2006-2019 for Precipitation over Potential Evapotranspiration (P/PET) as well as the population impacted by this variability.
Implications and Recommendations
As erratic climate events become the norm, early warning systems and adaptive strategies must be strengthened to sufficiently warn communities and mitigate drought impacts, including building resilience in pastoralist communities. aWhere’s daily-updated data provides the historical observed data needed to make data-driven decisions as well as the current conditions to provide relevant information to farmers and officials on how weather patterns are impacting forage, crop production and water supply. With accurate weather data, Africa can builds resilience to weather variability and adapts to climate change.