Localized drought due to lack of rainfall (WFP, UNEP & NEPA - 2016)

To identify areas which have experienced more frequent or intense rainfall-related drought, we looked at two climate indicators: change in spring precipitation and change in Standardized Precipitation-Evapotranspiration Index (SPEI). Unlike average annual rainfall, which simply tells us that an area has received less total rainfall than normal over an entire year (i.e. meteorological drought), spring precipitation and SPEI give a better indication of where rainfall anomalies might actually have significant negative impacts on crops and livestock (i.e. agricultural drought). Spring precipitation is especially important for rain fed crop cultivation in Afghanistan, as it occurs during a critical stage of plant growth. For this analysis, spring was defined as the months from January to April. The Standardized Precipitation Evapotranspiration Index (SPEI) is widely-used drought indicator, which takes into account not only precipitation but also potential evapotranspiration. For this analysis, the SPEI was calculated over a 12 month period .

Methodology: Information on past climate trends was produced by UNEP and NEPA through reanalysis—a method which combines climate models with observations (satellite and rain-station data). This method was selected due to the scarcity of historical climate observations for Afghanistan before the start of satellite observations in the 1980s, which would make an analysis based solely on observations unreliable. Climate reanalysis are numerical description of the past climate, produced by combining the outputs from climate model with climate observations. Out of the four reanalysis products which were evaluated, the Global Soil Wetness Project Phase 3 (1901-2010) (GSWP3) was selected for this analysis because of its overall good performance over Afghanistan, and its temporal coverage of the entire period of interest, 1950-2010. GSWP3 is generated globally on a 0.5° x 0.5 ° grid.

Source: The map comes from a report "Climate Change in Afghanistan: What does it Mean for Rural Livelihoods and Food Security?", which was produced jointly by the World Food Programme (WFP), the United Nations Environment Programme (UNEP) and Afghanistan's National Environmental Protection Agency (NEPA). The map was produced based on the livelihood zones produced by FEWSNET.