East Africa Drought Watch is a near-real time system that uses Earth Observation and Weather Information to monitor drought conditions in the East Africa region
The platform is a service developed as part of the Intra-ACP Climate Services Project in collaboration with the Drought group of the Natural Disaster Risk Unit at the Joint Research Centre of the European Commission. The system is adopted from the European Drought Observatory and adapted to the conditions in the East Africa region.
Drought is a recurrent feature of the climate that results from a shortfall in precipitation over an period of time, its inadequate timing compared to the needs of the vegetation cover, or a negative water balance due to an increased potential evapo-transpiration caused by high temperatures.
These conditions may be exacerbated by strong winds, atmospheric blocking patterns and antecedent conditions in soil moisture, reservoirs and aquifers, for example. If this situation leads to an unusual and temporary deficit in water availability, it is termed a drought. Droughts are to be distinguished from aridity, a permanent climatic feature, and from water scarcity, a situation where the climatologically available water resources are insufficient to satisfy long-term average water requirements.
Period with an abnormal precipitation deficit, in relation to the long-term average conditions for a region.
Amongst the indicators of meteorological drought, the Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) are the most well-known. They are probabilistic measures of the severity of anomalous dry events, which can be calculated for various rainfall accumulation periods (e.g. 1 to 48 months) and statistically linked to impacts in different economic and environmental sectors.
Snowpack or snow water equivalent (SWE) is another important variable in Northern Europe and in mountainous regions, which affects water availability over the year, by snow accumulation and melt.
When a meteorological drought leads to a soil moisture deficit that limits water availability for natural vegetation and crops.
Drought indicators based on soil water content, such as EDO’s Soil Moisture Anomaly (SMA), the Drought Severity Index (DSI), or the Palmer Drought Severity Index (PDSI), aim to characterize the impact on plant water stress.
Associated with the effects of periods of shortfalls of precipitation (including snowfall), on surface or sub-surface water supply (i.e. streamflow, reservoir and lake levels, and groundwater)
Indicators of hydrological drought, such as EDO’s Low Flow Index (LFI), are usually based on threshold approaches to quantify the volume of water deficit in rivers and reservoirs
When the demand for some economic goods and services (e.g. water, animal fodder, food grains, fish, hydro-electric power) exceeds supply as a result of a weather-related shortfall in water availability.
