| Co-Investigator(Kenkyū-buntansha) |
OHMIJA Tatsuo Okinawa Prefectural Institute of Health and Environment, Soil Run-off Section, Section Manager, 赤土研究室, 研究室長
FUJII Satoshi Subtropical Environment Remote-Sensing Center, Communications Research Laboratory, Head, 沖縄亜熱帯計測技術センター, 所長
NIHEI Yasuo Science University of Tokyo, Faculty of Science and Technology, Lecturer, 理工学部, 専任講師 (60262268)
YASUMURA Shigeki Japan Coral Reef Conservation & Research Center, サンゴ礁保護研究センター, センター員
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| Research Abstract |
1) Field observations using moored buoy systems with various logger-type sensors, GPS-installed small drifters and others were performed at Shiraho reef in Ishigaki Island in July to September 2000 and July in 2001to find characteristics of currents, waves, temperature salinity, turbidity, etc. The hydrodynamic feature, especially the mean flow field, in the reef are found to be governed by the spatial non-uniformity of the reef topography such as the S1ze and locations of the channels, shoals and reef edges.
2) A smaller scale measurement to observe 3-D local current and temperature fields around coral communities was made also at Shiraho reef in the same period, revealing their characteristic features and the fact that corals may absorb light more effectively than coral sands.
3) The watershed-based numerical model to simulate soil erosion and subsequent discharge into adjacent reef areas with input data such as precipitation, vegetation, soil type and topography has been developed and
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validated with the field data on time histories of turbidity at the Todoroki river taken continuously from June 2000.
4) For examining the long-distance transport of coral larvae. which may be important in the restoration process of the heavily damaged coral reefs due to mass bleaching in 1998 summer a field measurement using an HF-ocean radar system, newly-developed GPS-installed drifters and others was performed to clarify the physical process of the sea-surface currents and the Lagrangian trajectories of tracers at the sea surface in the region connecting the Kerama Ms. and the west coast of the Okinawa Id. Besides larval behavior in the water column and settlement at the bottom were investigated in a laboratory. These results demonstrate that Kerama Isls. may act as a source area supplying appreciable amount of coral larvae to the west coast of Okinawa Isl.
5) At Fukido and Miyara river moth areas in July and August 2001 a field observation was made to clarify the fundamental characteristics of physical environments of mangrove and sea-grass areas.
6) With these field data, numerical models to simulate shallow water turbulent flows in the reef, which governs material and thermal transport in the reef, and coastal 3-D currents in a wide have been developed with the basis of SDS-Q3D model and POM-dual sigma coordinate model, respectively.
7) As a basic theoretical tool for remote sensing of coral reef environments such as benthic cover, a 3-D optical model for coral canopy was developed. Less
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