The word “drought” is a relative term, and is defined differently by different regions and sources. Webster’s Dictionary defines drought as “a long period of no rain”; though this is an inadequate definition for the water supply industry. Wikipedia describes drought in stages and effects: “As a drought persists, the conditions surrounding it gradually worsen and its impact on the local population gradually increases. Droughts go through three stages before their ultimate cessation.

Meteorological drought is brought about when there is a prolonged period with less than average precipitation.  Meteorological drought usually precedes the other kinds of drought.

Agricultural droughts are droughts that affect crop production or the ecology of the range. This condition can also arise independently from any change in precipitation levels when soil conditions and erosion triggered by poorly planned agricultural endeavors cause a shortfall in water available to the crops. However, in a traditional drought, it is caused by an extended period of below average precipitation.

Hydrological drought is brought about when the water reserves available in sources such as aquifers, lakes and reservoirs falls below the statistical average. Like an agricultural drought, this can be triggered by