Wai‘anae Ecological Characterization

Drought Conditions

A drought is simply defined as a period of abnormally dry weather. A drought's severity can be affected by factors such as high temperatures, high winds, and low relative humidity. Drought can also result from human activities that increase demand for water. Expanding populations and increased irrigation put pressure on water supplies. A drought classified as "serious" means the rainfall is within 5 to 10 percent of historical totals. In a "severe" drought, rainfall is less than 5 percent of normal.

In Hawai‘i, rainfall totals can be highly variable from one year to another. This variability is evident in the precipitation extremes for locations across O‘ahu. For example, in 1951, the Wai‘anae Valley received 52.67 inches of rain. In the following year (1952), the same area only received 14.32 inches of precipitation (Western Regional Climate Center 2003). If a period of below-average rainfall is followed by a period of above-average temperatures, drought conditions can develop rapidly.

Droughts have impacted almost every island in Hawai‘i, with the most severe droughts of the past 15 years occurring in association with the El Niño phenomenon. El Niño is a disruption of the ocean-atmosphere system in the tropical Pacific. The results of El Niño are increased rainfall along the southern portion of the North American continent and droughts in the west Pacific. During the El Niño years, droughts have occurred during the winter-spring period. Please see the Climate Change and Variability section for more information about the effects of El Niño.

Recorded Droughts within the Hawaiian Islands

Year	Area	Remarks
1901	North Hawai‘i	Severe drought, destructive forest fires.
1905	Kona, Hawai‘i	Serious drought and forest fires.
1908	Hawai‘i and Maui	Serious drought.
1912	Kohala, Hawai‘i	Serious drought and severe sugarcane crop damage for two years.
1952	Kaua‘i	Long, severe dry spell.
1953	Hawai‘i, Kaua‘i, Maui and O‘ahu	Water rationing on Maui ; water tanks in Kona almost empty; 867 head of cattle died; pineapple production on Moloka‘i reduced by 30 percent; rainfall in the islands had been 40 percent less than normal.
1962	Hawai‘i and Maui	State declared disaster for these islands; crop damage, cattle deaths, and severe fire hazards; losses totaled $200,000.
1965	Hawai‘i	State water emergency declared; losses totaled $400,000.
1971	Hawai‘i and Maui	Irrigation and domestic water users sharply curtailed.
1975	Kaua‘i and O‘ahu	Worst drought for sugar plantations in 15 years.
1977 - 1978	Hawai‘i and Maui	Declared state disaster for these islands.
1980 - 1981	Hawai‘i and Maui	State-declared disaster; heavy agricultural and cattle losses; damage totaling at least $1.4 million.
1983 - 1985	Hawai‘i	El Niño effect; state-declared disaster; crop production reduced by 80 percent in Waimea and Kamuela areas; $96,000 spent for drought relief projects.
1996	Hawai‘i, Maui, and Moloka‘i	Declared drought emergency; heavy damage to agriculture and cattle industries; losses totaling at least $9.4 million.
1998 - 1999	Hawai‘i and Maui	State-declared drought emergency for Maui; county-declared emergency for Hawai‘i due to water shortages; heavy damage to agriculture and cattle industries; statewide cattle losses alone estimated at $6.5 million.
2000 - 2002	Hawai‘i, Maui, Moloka‘i, O‘ahu, Kaua‘i	Counties declare drought emergencies; Governor proclaims statewide drought emergency; Secretary of Interior designates all counties as primary disaster areas due to drought; East Maui streams at record low levels; statewide cattle losses alone projected at $9 million.

Source: Commission on Water Resource Management (State of Hawaii DLNR 2003).

Effects and Impacts

The impacts of a drought are not always immediate or obvious to the average person. The impacts may include reduced crop yields, diminished livestock herds, dried-up streams, lower water levels in irrigation ditches and reservoirs, depleted groundwater supplies, the increased probability of forest and brush fires, reduced tourism, and mandatory water conservation.  

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

As undeveloped areas get continually drier during drought conditions, a heightened potential for wild fires develops. If a fire does start, extinguishing the fire becomes a greater challenge in times of drought because of drier grasses and ground cover and also because of low water levels in irrigation reservoirs. Because of the salinity of the ocean, the waters of the Pacific cannot be used in fire-fighting efforts.

The tourism industry of Hawai‘i thrives due to the beauty of the islands and the easy access to most locations. Wild fires cause major devastation to affected areas, and drought conditions may cause public access to be limited in some areas to prevent fires. Both situations can adversely impact tourism and the economy near an affected wild-fire location.

In response to continued drought conditions, conservation efforts may be put into effect. These usually start out as voluntary efforts, but if the drought continues, conservation efforts may become mandatory and strictly enforced. Typical conservation efforts include public awareness campaigns and restricted residential water use for irrigation. If a drought continues, conservation efforts begin to target the large-scale users, such as industry and agriculture. These types of conservation efforts include crop reduction and increased fees for water usage.

References Cited

State of Hawaii Department of Land and Natural Resources (DLNR). 2003. Hawaii Drought Monitor. Commission on Water Resource Management. http://www.hawaii.gov/dlnr/cwrm/drought/index.htm

Western Regional Climate Center. 2003. Comparative Data for the Western States:Hawaii Monthly Average Precipitation (inches). Monthly Data Through End of 2002. http://www.wrcc.dri.edu/htmlfiles/hi/hi.ppt.html

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