Drought has been called a creeping disaster because of the way it develops slowly. Drought doesn't make the headlines the same way other disasters do, but its impacts on crops and water supplies rival those of other disasters. Drought is a persistent and abnormal moisture deficiency having adverse impacts on vegetation, animals or people. There are dozens of more specific drought definitions used around the world based on the lack of rain over various time periods or measured impacts such as reservoir levels or crop losses. Because of the various ways people measure drought, no one has produced an objective drought definition upon which everyone can agree.
Hydrological drought refers to deficiencies in surface and subsurface water supplies.
It is measured as streamflow, and as lake, reservoir, and ground water levels. Agricultural drought occurs when there isn't enough soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought is typically evident after meteorological drought but before a hydrological drought. Key Concepts Drought is a normal part of virtually every climate on Earth. Each place needs its own working definition of drought.