The indicators and indices listed below are based on the IDMP Handbook on Drought Indicators and Indices and have been drawn from IDMP and partner literature and online searches. They are categorized by type and ease of use, and grouped into the following classifications: (a) meteorology, (b) soil moisture, (c) hydrology, (d) remote sensing and (e) composite or modelled. Although listed by ‘ease of use’, it is possible that any, all or none of the indicators may be suitable for a particular application, based on user knowledge, needs, data availability and computer resources available to implement them. The resource needs increase from green to yellow to red, as outlined below. Again, the simplest index/indicator is not necessarily the best one to use.
If you have additional questions regarding the use and calculation of a specific indicator or index, please post an according question to our IDMP Community of Practice.
| Index | Type | Ease of use | Input parameters | Additional information |
|---|---|---|---|---|
| Aridity Anomaly Index (AAI) | Meteorology | A Green | precipitation, temperature, potential evapotranspiration, evapotranspiration | Operationally available for India |
| Deciles | Meteorology | A Green | precipitation | Easy to calculation; examples from Australia are useful |
| Keetch-Byram Drought Index (KBDI) | Meteorology | A Green | precipitation, temperature | Calculations are based upon the climate of the area of interest |
| Percent of Normal Precipitation | Meteorology | A Green | precipitation | Simple calculations |
| Standardized Precipitation Index (SPI) | Meteorology | A Green | precipitation | Highlighted by the WMO as a starting point for meteorological drought monitoring |
| Weighted Anomaly Standardized Precipitation (WASP) | Meteorology | A Green | precipitation, temperature | Uses gridded data for monitoring drought in tropical regions |
| Aridity Index (AI) | Meteorology | B Yellow | precipitation, temperature | Can also be used in climate classifications |
| China Z Index (CZI) | Meteorology | B Yellow | precipitation | Intended to improve upon SPI data |
| Crop Moisture Index (CMI) | Meteorology | B Yellow | precipitation, temperature | Weekly values are required |
| Drought Area Index (DAI) | Meteorology | B Yellow | precipitation | Gives an indication of monsoon season performance |
| Drought Reconnaissance Index (DRI) | Meteorology | B Yellow | precipitation, temperature | Monthly temperature and precipitation are required |
| Effective Drought Index (EDI) | Meteorology | B Yellow | precipitation | Program available through direct contact with originator |
| Hydro-thermal Coefficient of Selyaninov (HTC) | Meteorology | B Yellow | precipitation, temperature | Easy calculations and several examples in the Russian Federation |
| NOAA Drought Index (NDI) | Meteorology | B Yellow | precipitation | Best used in agricultural applications |
| Palmer Drought Severity Index (PDSI) | Meteorology | B Yellow | precipitation, temperature, available water content | Not green due to complexity of calculations and the need for serially complete data |
| Palmer Z Index | Meteorology | B Yellow | precipitation, temperature, available water content | One of the many outputs of PDSI calculations |
| Rainfall Anomaly Index (RAI) | Meteorology | B Yellow | precipitation | Serially complete data required |
| Self-Calibrated Palmer Drought Severity Index (sc-PDSI) | Meteorology | B Yellow | precipitation, temperature, available water content | Not green due to complexity of calculations and serially complete data required |
| Standardized Anomaly Index (SAI) | Meteorology | B Yellow | precipitation | Point data used to describe regional conditions |
| Standardized Precipitation Evapotranspiration Index (SPEI) | Meteorology | B Yellow | precipitation, temperature | Serially complete data required; output similar to SPI but with a temperature component |
| Agricultural Reference Index for Drought (ARID) | Meteorology | C Red | precipitation, temperature, modelled | Produced in south-eastern United States of America and not tested widely outside the region |
| Crop-Specific Drought Index (CSDI) | Meteorology | C Red | precipitation, temperature, dew point temperature, solar radiation, available water content, modelled, crop data | Quality data of many variables needed, making it challenging to use |
| Reclamation Drought Index (RDI) | Meteorology | C Red | precipitation, temperature, snowpack, reservoir, streamflow | Similar to the Surface Water Supply Index, but contains a temperature component |
| Soil Moisture Anomaly (SMA) | Soil moisture | B Yellow | precipitation, temperature, available water content | Intended to improve upon the water balance of PDSI |
| Evapotranspiration Deficit Index (ETDI) | Soil moisture | C Red | modelled | Complex calculations with multiple inputs required |
| Soil Moisture Deficit Index (SMDI) | Soil moisture | C Red | modelled | Weekly calculations at different soil depths; complicated to calculate |
| Soil Water Storage (SWS) | Soil moisture | C Red | available water content, reservoir, soil type, soil water deficit | Owing to variations in both soil and crop types, interpolation over large areas is challenging |
| Palmer Hydrological Drought Index (PHDI) | Hydrology | B Yellow | precipitation, temperature, available water contect | Serially complete data required |
| Standardized Reservoir Supply Index (SRSI) | Hydrology | B Yellow | reservoir | Similar calculations to SPI using reservoir data |
| Standardized Streamflow Index (SSFI) | Hydrology | B Yellow | streamflow | Uses the SPI program along with streamflow data |
| Standardized Water-level Index (SWI) | Hydrology | B Yellow | groundwater | Similar calculations to SPI, but using groundwater or well-level data instead of precipitation |
| Streamflow Drought Index (SDI) | Hydrology | B Yellow | streamflow | Similar calculations to SPI, but using streamflow data instead of precipitation |
| Surface Water Supply Index (SWSI) | Hydrology | B Yellow | precipitation, reservoir, streamflow, snowpack | Many methodologies and derivative products are available, but comparisons between basins are subject to the method chosen |
| Aggregate Dryness Index (ADI) | Hydrology | C Red | precipitation, evapotranspiration, streamflow, reservoir, available water content, snowpack | No code, but mathematics explained in the literature |
| Standardized Snowmelt and Rain Index (SMRI) | Hydrology | C Red | precipitation, temperature, streamflow, modelled | Can be used with or without snowpack information |
| Enhanced Vegetation Index (EVI) | Remote sensing | A Green | satellite | Does not separate drought stress from other stress |
| Evaporative Stress Index (ESI) | Remote sensing | A Green | satellite, potential evapotranspiration | Does not have a long history as an operational product |
| Normalized Difference Vegetation Index (NDVI) | Remote sensing | A Green | satellite | Calculated for most locations |
| Temperature Condition Index (TCI) | Remote sensing | A Green | satellite | Usually found along with NDVI calculations |
| Vegetation Condition Index (VCI) | Remote sensing | A Green | satellite | Usually found along with NDVI calculations |
| Vegetation Drought Response Index (VegDRI) | Remote sensing | A Green | satellite, precipitation, temperature, available water content, land cover, evapotranspiration | Takes into account many variables to separate drought stress from other vegetation stress |
| Vegetation Health Index (VHI) | Remote sensing | A Green | satellite | One of the first attempts to monitor drought using remotely sensed data |
| Water Requirement Satisfaction Index (WRSI and Geo-spatial WRSI) | Remote sensing | A Green | satellite, modelled, crop coefficients | Operational for many locations |
| Normalized Difference Water Index (NDWI) and Land Surface Water Index (LSWI) | Remote sensing | A Green | satellite | Produced operationally using Moderate Resolution Imaging Spectroradiometer data |
| Soil Adjusted Vegetation Index (SAVI) | Remote sensing | C Red | satellite | Not produced operationally |
| Combined Drought Indicator (CDI) | Composite or modelled | A Green | modelled, precipitation, satellite | Uses both surface and remotely sensed data |
| Global Integrated Drought Monitoring and Prediction System (GIDMaPS) | Composite or modelled | A Green | multiple, modelled | An operational product with global output for three drought indices: Standardized Soil Moisture Index, SPI and Multivariate Standardized Drought Index |
| Global Land Data Assimilation System (GLDAS) | Composite or modelled | A Green | multiple, modelled, satellite | Useful in data-poor regions due to global extent |
| Multivariate Standardized Drought Index (MSDI) | Composite or modelled | A Green | multiple, modelled | Available but interpretation is needed |
| United States Drought Monitor (USDM) | Composite or modelled | A Green | multiple | Available but interpretation is needed |