Groundwater Drought Assessment
EO Capability Benefits
Groundwater drought assessment involves evaluating the status of aquifers and their response to prolonged periods of water scarcity. This EO capability is based on satellite-based measurements of groundwater storage anomalies to provide a consistent and robust assessment of drought conditions. Key aspects of groundwater drought assessment include detecting drought from underground water storage, drought analysis, and developing drought management strategies. While tracking changes in water levels is crucial for understanding aquifer response to drought, key information on drought severity, frequency, duration, and corresponding trends can be inferred through time series analysis of drought indicators at the pixel level. The information acquired from groundwater drought assessments is essential for developing effective strategies to mitigate the impacts of drought and ensure sustainable water resource use.
EO Capability Description
The groundwater drought assessment is based on the implementation of the Grace Groundwater Drought Index (GGDI), a drought monitoring index used to assess the state of groundwater levels relative to long-term averages using GRACE-derived data. More specifically, the GGDI is a continuous index of groundwater drought based on the methodology of other commonly used drought indicators such as the Standardized Precipitation Index (SPI). In areas with available in-situ measurements, the corresponding drought indicator (Standardized Groundwater Index) can also be calculated to have a more robust estimation.
The methodology used is comparable across regions with different climates and can be calculated for different accumulation periods (e.g. 3-months is used as default to provide an indication of droughts with immediate impacts).
Although the use of a three-month accumulation is used most frequently, shorter, or longer time periods may be considered depending on the context and purpose. Using the monthly groundwater drought index data, it also possible to calculate: the drought frequency of occurrence, duration, and severity.
The combined analysis of groundwater storage anomalies (see related EO Capability) and the drought assessments offers a comprehensive view of groundwater variability that can be implemented over the last two decades up to the present.
