The 1983 drought in the western Pacific

Abstract

A severe drought, from late 1982 until mid-1983, on many islands in the Western Pacific Ocean is attributed to the El Nino effect, a change in oceanic circulation that is typically associated with the Eastern South Pacific Ocean. Because of a lessening of the trade winds, warm Western Pacific seawater flowed abnormally to the west coast of the Americas, inducing an El Nino effect that was possibly the strongest in 100 years. Of the values for total monthly rainfall recorded January through May 1983 at long-term rainfall stations in the Western Pacific, half were the lowest of record. West of longitude 155 t., total rainfall for the five-month period was 28 percent of normal; east of this longitude, 13 percent of normal. In islands of the Caroline and the Marshall groups, recurrence interval of the drought is estimated at 125 years for Koror (Palau Islands), Yap Island, and Majuro (Marshall Islands); and at 250 years for Pohnpei and Kosrae. For most streams in the Caroline Islands, average monthly streamflow for January through May 1983 was the lowest of record each month. On Pohnpei, the streamflow for January through May was ^ to 7 percent of normal; on Moen (Truk Islands), 8 percent; on Kosrae for January through April, 3 to 7 percent of normal. On Moen, the average chloride concentration of ground water (the main source of water for the island) increased from 78 milligrams per liter on February 10 to ^10 milligrams per liter on April 20, 1983. On Saipan, chloride concentration increased by a third, to a value of 878 milligrams per 1iter. Water-conservation measures were imposed on islands affected by the drought. On Guam, conservation was voluntary; on Majuro, water was available for only one hour every third day; and on Jaluit Atoll (Marshall Islands), one gallon per person per day was allowed. Losses of staple food crops (taro, coconut, and breadfruit) were severe, especially on Pohnpei, Kosrae, and in the Marshall Islands. At least half the population of the Caroline and Marshall Islands received U.S. Department of Agriculture food supplements.