About the Canadian Drought Monitor

The Canadian Drought Monitor (CDM) uses a variety of federal, provincial, and regional data sources to establish a single drought rating based on a five category system. These ratings are shared through monthly maps that show the extent and intensity of drought across Canada. Tracking drought across the country is challenging, as there are varying definitions and indicators used to measure and define its extent and severity. The CDM overcomes these challenges by combining multiple indicators and impacts, and through consultations with federal, provincial, regional, and academic scientists.

Background

Since 2002 Agriculture and Agri-Food Canada has been the lead agency responsible for providing monthly assessments of drought for Canada that feed directly into the North American Drought Monitor (NADM), a cooperative effort between drought experts in Canada, Mexico and the United States. The NADM is based on the methodology of the highly successful United States Drought Monitor (USDM), and as such, has been developed to provide an ongoing comprehensive and integrated assessment of drought throughout all three countries in North America.

A number of provincial and federal organizations are consulted to produce the CDM, in addition to ongoing communication with international partners. In the United States, partners include the National Oceanic and Atmospheric Administration's National Climatic Data Center (NCDC) and the National Drought Mitigation Centre. In Mexico, partners include the National Meteorological Service of Mexico (in Spanish only) (Servicio Meteorológico Nacional – SMN) which operates the Mexico Drought Monitor (in Spanish only).

Data sources

Drought is a "creeping phenomenon" – difficult to define and measure, slow to develop, continuous, cumulative, and long lasting. There is no universally applicable tool for measuring drought; as impacts are non-structural, spread over large areas, and best described by multiple indices.

To address the challenges of monitoring drought in a comprehensive way, the CDM is developed from an assortment of sources, such as: various precipitation and temperature indicators, Normalized Difference Vegetation Index satellite imagery, streamflow values, Palmer Drought Index, Standardized Precipitation Index; as well as drought indicators used by the agriculture, forestry, and water management sectors. Drought-prone regions are analyzed based on precipitation, temperature, drought model index maps, and climate data; and are interpreted by federal, provincial, and academic scientists. Once a consensus is reached, a monthly map showing drought designations for Canada is produced and used by Agriculture and Agri-Food Canada (AAFC) to assess the current drought risk to agriculture.

Classification scheme

The CDM uses a five category system to define the severity, spatial extent, and impacts of drought. Drought classes in the CDM range from D0 to D4, with D0 indicating abnormally dry conditions, and D1 to D4 indicating moderate to exceptional drought. Each category is based on the percentile chance of those conditions occurring. An exceptional drought (D4) for example, represents conditions that historically only appear less than two years in one hundred. Currently the spatial extent of the CDM maps encompasses these five categories across all of Canada except Nunavut and the Arctic Archipelago.

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