Maui Drought Workshop 08

8/6/2019 Maui Drought Workshop 08

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Hawaii Drought


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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.


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Drought can be characterized from the perspectives ofmeteorology,agriculture, hydrology, and socio-economic impacts.

The meteorological perspective would describe drought as a rainfall deficitcompared with some normal or expected rainfall amount.

The agricultural perspective could describe drought by its impacts on theagricultural industry due to reduced rainfall and water supply (e.g., croploss, herd culling, etc.).

Hydrological descriptions of drought may compare stream flows, groundwater, and reservoir levels to normal conditions.

Drought can also be described from the socio-economic perspective by thedirect and indirect impacts droughts have on society and the economy (e.g.,increased unemployment due to failure of an industry because of drought).


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Historical statewide drought events (Hawaii DroughtMonitor and R88)

Year Area Remarks

1901 North Hawaii Severe drought, destructive forest fires.

1905 Kona, Hawaii Serious drought and forest fires.

1908 Hawaii and Maui Serious drought.

1912 Kohala, Hawaii Serious drought and severe sugarcane crop damage for two years.

1952 Kauai Long, severe dry spell.

1953 Hawaii, Kauai, Maui and Oahu Water rat ioning on Maui; Water tanks in Kona almost empty; 867 head of catt le died;Pineapple production on Molokai reduced by 30 percent; Rainfall in the islands hadbeen 40 percent less than normal.

1962 Hawaii and Maui State declared disaster for these islands; Crop damage, cattle deaths, and sever firehazards; Losses totaled $200,000.

1965 Hawaii State water emergency declared; Losses totaled $400,000.

1971 Hawaii and Maui Irrigation and domestic water users sharply curtailed.

1975 Kauai and Oahu Worst drought for sugar plantations in 15 years.

1977-1978 Hawaii and Maui Declared State disaster for these islands.

1980-1981 Hawaii and Maui State declared disaster; Heavy agricultural and cattle losses; Damages totaling at least $1.4 million.


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1983 - 1985 Hawaii El Nio effect; State declared disaster; Crop productionreduced by 80 percent in Waimea and Kamuela areas;$96,000 spent for drought relief projects.

1996 Hawaii, Maui, and Molokai Declared drought emergency; heavy damages toagriculture and cattle industries; Losses totaling atleast $9.4 million.

1998 - 1999 Hawaii and Maui State declared drought emergency for Maui; County declaredemergency for Hawaii due to water shortages; heavy

damages to agriculture and cattle industries; Statewidecattle losses alone estimated at $6.5 million.

2000 - 2002 Hawaii, Maui, Molokai, Oahu,Kauai

Counties declare drought emergencies; Governorproclaims statewide drought emergency; Secretary ofInterior designates all Counties as primary disasterareas due to drought; East Maui streams at record lowlevels; Statewide cattle losses alone projected at$9 million.

2008-?


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Correlation coefficients between the seasonal SOI and the seasonal Hawaiian rainfall index.

Quenouilles (1952) method was used to account for the reduction of effective numbers of degrees of freedom due to

persistence. One and two asterisks indicate significance at the 5 and 1 percent levels, respectively.

Rainfall

SOI Summer Autumn Winter Spring

Spring -0.03 -0.05 0.26 0.17

Summer -0.12 -.011 0.54** 0.34*

Autumn -0.21 0.44** 0.40**

Winter 0.47** 0.50**


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Winter rainfall difference (inches) of the (El Nio/+PDO)

minus (La Nia/-PDO) composite. Dots for rainfall stations

(272).


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The nonparametric Mann-Whitney test for winter rainfall

difference of the (El Nio/+PDO) minus (La Nia/-PDO).


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Winter composite of SST (shading) and surface wind

(vectors). The unit for SST is C and for wind vectors is m/s.


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Winter 200-mb wind vectors. Isotach interval is 10 m/s.

Area with wind speed greater than 40 m/s is shaded.


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Winter composite of east-west vertical circulation. Longitude-height

section of zonal wind and negative pressure vertical velocity (U, -) is

averaged over 15-25N. Shading is for statistical significance. The

Hawaiian Islands are bordered approximately by two vertical lines.


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The SPI has been embraced by NDMC,WRCC, and

the NWS/Honolulu Forecast Office.


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Drought classification based on SPI(NDMC)

SPI values Designation

0.00 to -0.99 Mild Drought

-1.00 to -1.49 Moderate Drought

-1.50 to -1.99 Severe Drought

-2.00 or less Extreme Drought


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Three-month SPI through the end of March 2007 for Kula Hospital 267

-3

-2

-1

0

1

2

3

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

SPI

2001-02


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Drought Risk and Vulnerability

Assessment and GIS Mapping Project


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Another index, the Keetch/Byram Drought Index (KBDI), has been

used for the southeast U.S. over 30 years.

The KBDI, which conceptually describes the soil moisture deficit,

is used to assess wildfire potential as part of the revised 1988

U.S. National Fire DangerR

ating System.

This index depends on daily rainfall amount, daily maximumtemperature, and the mean annual rainfall.


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The relationship between the KBDI and fire activity, as

measured by total areas burned, in the Hawaiian Islandswas explored (Dolling, Chu, Fujioka, 2005, Agricultural

and Forest Meteorology).

Total acres burned (TAB) data from DLNR. Records areshort, only 20 yrs (1976-96).

Because of the non-normally distributed nature of the

TAB, a log transformation is applied to the TAB data.The correlation between KBDI and TAB is significant for

Maui with a p-value well below the 5% level.


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A strong relationship between the KBDI and fire activity is

found for the islands of Maui and Hawaii.


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Summary

Reviewed historical drought events in Hawaii.

Drought in Hawaii generally follows an El

Nio event. Long-lead winter (spring) rainfall

prediction is feasible.

Drought is also affected by the PDO cycle.Rainfall difference between (El Nio/+PDO)

and (La Nia/-PDO).

Maui Drought Workshop 08

Documents

Transcript of Maui Drought Workshop 08