Development of Indicators and Triggers for Drought Plans; A Review

Drought plans as the main measure to mitigate negative impacts of this natural disaster depend on indicators and triggers that characterize drought conditions and indicate time and type of the predefined responses. There are important issues in developing the relevant indicators and triggers; such as combining approach, temporal and spatial inconsistency and statistical incomparability of these indicators and triggers. Also these indicators should be selected with respect to the objectives of the plans. The main goal of this paper is to address such issues and also introduce the advantages and disadvantages of the referred indicators. Finally, the significant role of expert assessment to finalize the selected approach is highlighted and discussed.