| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1999: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1998: ¥3,400,000 (Direct Cost: ¥3,400,000)
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| Research Abstract |
Surveys were done on water masses between a strait and sea. Convective circulation drives brackish water to flow out of small embayment, depending on phase between solar radiation and tide. An overstable shallow thermocline was seen inside the tidal front in summer, while an estuarine front as a thermohaline was along the coast in winter. Turbid water was steadily found on the shelf floor, irrespective of season. Contrast in the water column was around or less than ten. Thus, turbidity varies due to tidal currents flowing east-west, which should be measured by the ADP. The logarithmic profile of 50-60 cm/s was found at the maximum flooding (ebbing) tide, while others took the long+linear forms of 40-50 cm/s. different profiles were found in turning tides or places of gradually changing depths, which were close to linear+log profiles as wake flows of 80-90 cm/s. From logarithmic profiles adjacent to fully rough floors, the friction velocity range was 1.5-2 cm/s, equivalent roughness of 0.09-3.3 cm, with an equivalent sediment sizes of 20-50 μm. Concerning with DO in deep water, it was 40% saturated in July, 80% in November and 100% in December. Synchronizing to recovery in DO, chlorophyll exhibited turbid patterns above the shelf floor. In November, C : P ratio was about 100 to the Redfield's ratio, but N : P was 15 times the suggested value of 16. A dense bottom current containing diatoms was seen after the spring bloom, when a sinking pattern was seen toward the deeper water. A river plume was noticed as a depression of Na : light or dessolved matters were vertically uniform, while metals looked suspended. It was found metals were left in sides of the plume. Sediment transport under waves in vegetated areas was discussed from laboratory results. The turbid layer contains sediment, and other organic and inorganic matters, which shows a tendency of mixing in the area of the inland sea.
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