沖縄地域におけるペンマン法による蒸発位の時空間分布
2004 年 9 巻 2 号 p. 31-36
詳細
2004 年 9 巻 2 号 p. 31-36
The evapo-transpiration (ET) observed at Naha, prefectural capital of Okinawa, has commonly been used in scheduling upland-crop irrigation in any area of Okinawa. Estimating the ET endemic to an area of interest and using it in irrigation scheduling may lead to improvement of irrigation efficiency, or beneficial use of marginal water resources in Okinawa. In this context, the present paper deduces prefecture-wide spatiotemporal distribution of Penman-method-based potential evaporation (PE) from the meteorological data available in Okinawa areas, thus drawing monthly-varying iso-PE maps from which local PE-value at a particular location can be figured out. In mapping, the monthly averaged PEs estimated at a total of 18 meteorological stations are referred. However 10 stations out of 18 are devoid of humidity data that are basic needs for PE evaluation. Thus these are imported from the nearest stations to supply the lack. It is demonstrated that use of such imported data insignificantly affects PE-value It is further recognized that PE-values as well as ET-values obtained from multiplying PE by crop coeffi-cient not only temporally but also spatially vary, thus implying that common use of the ET-value at Naha throug-hout the prefecture is inappropriate in terms of beneficial use of water resources.
