WRRCTR No.156 Measured Evaporation in High Rainfall Areas, Leeward Ko'olau Ranges, O'ahu, Hawai'i

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dc.contributor.authorEkern, Paul C.
dc.date.accessioned2008-07-17T22:29:38Z
dc.date.available2008-07-17T22:29:38Z
dc.date.issued1983-10
dc.description.abstractAn evaporating surface made from a dark, porous carborundum stone, 6-in. (152.4-rnrn) in diameter, wetted by capillary rise from a plastic reservoir and shielded from rainfall by a clear plastic cover was designed for rainy areas. Class A pan evaporation at five different sites was 0.6 the water loss from corresponding evaporimeters. Water use by Californiagrass was 1.1 pan evaporation and 0.66 the water loss from the evaporimeter. Evaporation, rainfall, and pertinent meteorological factors were measured at one ridge and four valley sites on the Manoa transect in southern Oahu and at one valley and eight ridge sites on the Kipapa Ridge transect on the leeward Koolau Range slopes in central Oahu. Water use on the Kipapa transect was that predicted by the Priestley-Taylor relationship, while water use on the Manoa transect exceeded that predicted with positive advection from the urban surroundings and probable subsidence of the air from the Koolau crest. Measured rates exceeded those from empirical relationships based on extrapolation of pan evaporation measurements. Of the near normal 1981 rainfall of 149 in. (3784.6 mm), runoff was 27%, evaporation 28%, and deep percolate 45% for the Kipapa watershed water balance. Both runoff and evaporation were greater and percolate less than that given for the 1958 water balance. Direct interception of cloud water added an amount less than 2% of the rainfall on the watershed. Maximum short-term, deep percolation rates were no greater than 1.6 in. (40.64 mm)/day and runoff was 0.53 rainfall^1.28.
dc.description.sponsorshipBoard of Water Supply, City and Country of Honolulu
dc.format.extentix + 60 pages
dc.identifier.citationEkern PC. 1983. Measured evaporation in high rainfall areas, leeward Ko'olau Ranges, O'ahu, Hawai'i. Honolulu (HI): Water Resources Research Center, University of Hawaii at Manoa. WRRC technical report, 156.
dc.identifier.urihttp://hdl.handle.net/10125/1974
dc.language.isoen-US
dc.publisherWater Resources Research Center, University of Hawaii at Manoa
dc.relation.ispartofseriesWRRC Technical Report
dc.relation.ispartofseries156
dc.subjectevapotranspiration
dc.subjectpan evaporation
dc.subjectwater balance
dc.subjectrainfall
dc.subjectdeep percolation
dc.subjectwater use
dc.subjectrunoff
dc.subjectPriestley-Taylor relationship
dc.subjectManoa transect
dc.subjectKipapa transect
dc.subjectOahu
dc.subjectHawaii
dc.subject.lcshEvaporation -- Hawaii -- Oahu.
dc.subject.lcshKoolau Range (Hawaii)
dc.subject.lcshRain and rainfall -- Hawaii -- Oahu.
dc.titleWRRCTR No.156 Measured Evaporation in High Rainfall Areas, Leeward Ko'olau Ranges, O'ahu, Hawai'i
dc.typeReport
dc.type.dcmiText

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