Droughts can be considered as the opposite of floods.
Floods result from an overabundance of rainfall, droughts from a lack of rainfall.
One large rainstorm in the period of a drought may not end a drought. It may takes months of precipitation to end a drought. Whereas it is true that we in Illinois do enjoy an abundant source of water, both surface and ground water, it is not an inexhaustible resource. This fact is driven home during periods when the precipitation is below what is normally expected for a period of time. Drought, although hard to believe, can have a greater impact, financially and on human health, than floods.