Drought is a chronic and troublesome problem in Hawaii, at one time or another affecting virtually every part of the state.  These events often reduce crop yields, diminish livestock herds, desiccate streams, irrigation ditches and reservoirs, deplete groundwater supplies, and lead to forest and brush fires.   Periods of drought invariably give rise to water crises, sometimes requiring imposition of emergency conservation measures.

Drought can be characterized from the perspectives of meteorology, agriculture, hydrology, and socio-economic impacts.  For example, the meteorological perspective would describe drought as a rainfall deficit compared with some normal or expected rainfall amount.  The agricultural perspective could describe drought by its impacts on the agricultural industry due to reduced rainfall and water supply (e.g., crop loss, herd culling, etc.).  Hydrological descriptions of drought may compare stream flows, ground water, and reservoir levels to normal conditions.  Drought can also be described from the socio-economic perspective by the direct and indirect impacts droughts have on society and the economy (e.g., increased unemployment due to failure of an industry because of drought).  Lack of rainfall is not the only factor contributing to the impacts of drought.  Both natural events and human activities, such as expanding populations, irrigation, and environmental needs all put pressure on water supplies.  Lack of rainfall combined with the demands society place on on water systems and supplies contribute to drought impacts.  During the past 15 years, the most severe droughts impacting the Hawaiian Islands have been associated with the El Niño Phenomenon and persistent zones of high pressure systems throughout the islands.

The agriculture industry is usually the first to be impacted by drought.  Lack of rainfall and reduced irrigation water supplies can cause reduced yields, crop failure, and force farmers to delay planting or risk losing their crop.  Drought can destroy pasture and deplete drinking water for livestock.  Ranchers are forced to purchase feed and water and reduce herd sizes to cope with drought.

Another danger associated with the impacts of drought is the heightened potential of wildland fires during extended dry periods.  Continued economic growth and development in the wildland/urban interface areas has increased the risk to human life and property.  Other concerns include the availability of sufficient fresh water reservoirs to combat wildland fires and the looming threat of wildfire on former plantation lands no longer irrigated.

In the past, drought was addressed as a temporary emergency.  Actions were taken in response to impacts in a reactionary fashion.  The most important lesson learned in recent years is that the best time to reduce the impacts of drought is before they occur.  It is important to develop a plan that advocates a proactive drought management approach.  The Hawaii Drought Plan was framed with this approach in mind.

References:
1.  Hawaii Drought Plan, Phase 1, 2000. 
2.  Giambelluca, T.W.  1991.  Drought In Hawaii.   Report R88, Commission on Water Resource Management,
     Department of Land and Natural Resources, State of Hawaii.
3.  Department of Land and Natural Resources, Division of Forestry and Wildlife Website, 2001.
4.  National Drought Mitigation Center.  What is Drought?.  http://www.drought.unl.edu/whatis/concept.htm.