The IDMP glossary is a compilation of drought-related terms drawn from the most common and reliable glossaries in this domain.
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| Term | Definition | Source |
|---|---|---|
| Adaptation | The process of adjustment to actual or expected climate and its effects. In human systems, adaptation seeks to moderate or avoid harm or exploit beneficial opportunities. In some natural systems, human intervention may facilitate adjustment to expected climate and its effects. | IPCC, 2014 |
| Adaptive Capacity | The ability of systems, institutions, humans and other organisms to adjust to potential damage, to take advantage of opportunities, or to respond to consequences. | IPCC, 2014 |
| Aquifer | Underground layers of permeable rock, sediment or soil filled with water and interconnected, so the water stays within or flows through them. The two major types of aquifers are confined and unconfined. | GWP, 2017 |
| Aridity | Characteristic of a climate relating to insufficiency or inadequacy of precipitation to maintain vegetation (WMO). Aridity is measured by comparing long-term average water supply (precipitation) to long-term average water demand (evapotranspiration). If demand is greater than supply, on average, then the climate is arid (NOAA). | NOAA NCEI, 2017; WMO, 1992 |
| Available groundwater resource | Volume of water stored in an aquifer which is available for development and use (WMO-UNESCO). It is calculated as the difference between the long-term annual average rate of overall recharge of the body of groundwater and the long-term annual rate of flow required to achieve the ecological quality objectives for associated surface waters (surface waters that are recharged by groundwater) (EC). | EC, 2000; WMO/UNESCO, 2012 |
| Basin (catchment or watershed) | An area having a common outlet for its surface runoff. | WMO/UNESCO, 2012 |
| Climate change | A change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use. | IPCC, 2014 |
| Crop failure | Abnormal reductions in crop yield such that is insufficient to meet the nutritional or economic needs of the community. | EM-DAT, 2017 |
| Desalination | Water desalination: removal of salt from sea- or brackish water. It is achieved by various methods, for example distillation, reverse osmosis, hyperfiltration, electrodialysis, ion exchange, and solar evaporation followed by condensation of water vapour. Soil desalination: removal of salt from soil by artificial means, usually leaching. | FAO, 2017 |
| Desertification | Land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities. | UNCCD, 2019 |
| Disaster | A serious disruption of the functioning of a community or a society at any scale due to hazardous events interacting with conditions of exposure, vulnerability and capacity, leading to one or more of the following: human, material, economic and environmental losses and impacts. | UNISDR, 2017 |
| Disaster Risk | The potential loss of life, injury, or destroyed or damaged assets which could occur to a system, society or a community in a specific period of time, determined probabilistically as a function of hazard, exposure, vulnerability and capacity. | UNISDR, 2017 |
| Disaster Risk Management (DRM) | Disaster risk management is the application of disaster risk reduction policies and strategies to prevent new disaster risk, reduce existing disaster risk and manage residual risk, contributing to the strengthening of resilience and reduction of disaster losses. | UNISDR, 2017 |
| Disaster Risk Reduction (DRR) | Disaster risk reduction is aimed at preventing new and reducing existing disaster risk and managing residual risk, all of which contribute to strengthening resilience and therefore to the achievement of sustainable development. | UNISDR, 2017 |
| Drainage | Removal of surface water or groundwater from a given area by natural or artificial means. | WMO/UNESCO, 2012 |
| Drought | (1) Prolonged absence or marked deficiency of precipitation. (2) Period of abnormally dry weather sufficiently prolonged for the lack of precipitation to cause a serious hydrological imbalance. | WMO, 1992 |
| Drought assessment | Assessment reviewing drought conditions and indicating potential impacts for various economic sectors, such as agriculture and forestry. | NOAA NWS, 2017 |
| Drought forecast | The statistical estimate of the probability of occurrence of a future drought event. | GWP CEE, 2015 |
| Drought impact | A specific effect of drought on the economy, society, and/or environment, which is a symptom of vulnerability. | GWP CEE, 2015 |
| Drought impact assessment | The process of assessing the magnitude and distribution of the effects of a drought. | GWP CEE, 2015 |
| Drought index | Computed numerical representations of drought severity, assessed using climatic or hydrometeorological inputs, including precipitation, temperature, streamflow, groundwater and reservoir levels, soil moisture and snowpack. They aim to measure the qualitative status of drought on the landscape for a given time period. Indices are technically indicators as well. | WMO/GWP, 2016 |
| Drought indicator | Variables or parameters used to describe drought conditions. Examples include precipitation, temperature, streamflow, groundwater and reservoir levels, soil moisture and snowpack. | WMO/GWP, 2016 |
| Drought Management Plan | It is a planning tool that can be applied to the basin scale or to other scales. It aims to define mechanisms and a methodology for detecting and predicting droughts, establish thresholds for different stages of drought as it intensifies and recedes, define measures to achieve specific objectives in each drought stage, ensure transparency and public participation in the development of drought strategies. The main objective of drought management plans is to minimize the adverse impacts on the economy, social life and environment when drought appears. | GWP CEE, 2015 |
| Drought vulnerability assessment | It is a drought vulnerability quantification and description that consist in identifying the relevant factors influencing it, from the point of view of exposure, sensitivity and adaptive capacity. The final aim of a drought vulnerability assessment is to identify the underlying sources of drought impact. | Urquijo et al., 2015 |
| Dry spell | Period of abnormally dry weather. Use of the term should be confined to conditions less severe than those of a drought. | WMO, 1992 |
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