We set up
two experimental catchments to provide an improved understanding of
hydrological processes in a subtropical forested area in the northern part of
Okinawa Island, Japan. We calculated runoff using water level data (recorded by
a pressure-type water level gauge installed in a box culvert) and a discharge
rating curve (derived from in situ observations). Water balance calculations for 2010 showed that the rainfall,
runoff and evapotranspiration losses (= rainfall – runoff) were 3403.6 mm,
2285.7 mm and 1117.4 mm, respectively. This result was in agreement with
previous results from other forested experimental catchments in this region.
Direct runoff, as a proportion of event total rainfall, can be expressed by the
empirical equation (Qdirect = 0.0048, Pevent 1.7971,
R2 = 0.9599). When Pevent was 100 mm or less, the ratios of Qdirect to Pevent were less than
15% in general. When Pevent exceeded 100 mm, the ratios were 20% - 30%.
Cite this paper
Kabeya, N. , Shimizu, A. , Shimizu, T. , Ikuzawa, H. , Arakaki, T. , Furugen, H. , Ohnuki, Y. and Asano, S. (2014) Rainfall and Runoff Observations in the Subtropical Forest of Okinawa Island, Japan. Journal of Water Resource and Protection
, 625-634. doi: 10.4236/jwarp.2014.66061
 Wohl, E., Barros, A., Brunsell, N., Chappell, N.A., Coe, M., Giambelluca, T., Goldsmith, S., Harmon, R., Hendrickx, J., Juvik, J., McDonnell, J.J. and Ogden, F. (2012) The Hydrology of the Humid Tropics. Nature Climate Change, 2, 655-662.
 Gossling, S. (2001) The Consequences of Tourism for Sustainable Water Use on a Tropical Island: Zanzibar, Tanzania. Journal of Environmental Management, 61, 179-191. http://dx.doi.org/10.1006/jema.2000.0403
 Kakazu, H. (2011) Sustainable Island Tourism: The Case of Okinawa. In: Carlsen, J. and Butler, R., Eds., Island Tourism: Sustainable Perspectives, CAB International, Wallingford, 171-185. http://dx.doi.org/10.1079/9781845936792.0171
 Ishijima, S., Kimura, R., Yokoyama, T., Shimose, R. and Yoshinaga, A. (2000) Observations of the Surface Temperature of the Northern Region of the Okinawa Island with a Preliminary Analysis of Therein Water Balance. Bulletin of the Faculty of Science, University of the Ryukyus, 70, 49-62.
 Ito, M. (2010) The Water Resource Development in Okinawa Island. Shimatatei, 53, 14-18.
 Sueyoshi, M., Goto, H., Sato, H., Hattori, T., Kotaka, N. and Saito, K. (2009) Clusiidae (Diptera) from Log Emergence Traps in the Yambaru, a Subtropical Forest of Japan. Entomological Science, 12, 98-106. http://dx.doi.org/10.1111/j.1479-8298.2009.00302.x
 Ikuzawa, H. and Kinjyo, M. (1995) Forest Hydrological Catchments in Okinawa. Forest Technology, 644, 13-18.
 Fujieda, M., Shimizu, T., Kinjou, M. and Terazono, R. (1995) Hydrologic Environment in Head Areas on Okinawa Island. Journal of Japanese Forest Society, 77, 145-152.
 Kanna, K., Arakaki, T. and Kinjyo, M. (2001) Effect of Erosion Control Work on Forest Watershed Conservation—A Case Study of Hydrological Observation at Hentona of Kunigami Village. Bulletin of Okinawa Forest Research Institute, 44, 1-14.
 Yoshinaga, A. and Onaga, K. (1993) Effect for Surface Runoff in Small Basin Due to Deforestation. The Science Bulletin of the College of Agriculture, University of Ryukyus, 40, 69-75.
 Kabeya, N., Shimizu, A., Shimizu, T., Arakaki, T., Furugen, H., Ikuzawa, H. and Ohnuki, Y. Canopy Interception Bservations in the Northern Forest of Okinawa Island. Kyushu Journal of Forest Research, in Press.
 Kabeya, N., Shimizu, A., Shimizu, T., Asano, S., Ikuzawa, H., Imada, M., Higa, M. and Fugugen, H. (2011) Rainfall and Runoff Observations in Forested Watersheds Located in the Sub-Tropic Small Island (II). Kyushu Journal of Forest Research, 64, 105-107.
 Japan Society of Hydrology and Water Resources (1997) The Handbook of Hydrology and Water Resources. Asakura Publishing Co. Ltd., Tokyo, 636 p.
 Japan Society of Civil Engineers (1985) Hydraulic Formula Book—1985 Editions. Gihodo Shuppan, Tokyo, 625 p.
 Shimizu, A., Miyabuchi, Y., Shimizu, T., Ogawa, Y., Daimaru, H., Sato, T. and Takeshita, M. (2008) Statistical Report of Hydrological Observations at the Sarukawa Experimental Watershed (January 1987 to December 2000). Bulletin of Forestry and Forest Products Research Institute, 406, 13-65.
 Asano, S., Shimizu, A., Kabeya, N., Hagino, H. and Tamai, K. (2011) Statistical Report of Hydrological Observations at the Sarukawa Experimental Watershed (January, 2001 to December, 2005). Bulletin of Forestry and Forest Products Research Institute, 407, 49-71.