In this study, we proposed a method, which promotes the entrainment of seawater by equipping the river
mouth with the weir, and the effect was examined based on experimental and theoretical analysis. These results
could be summarized as follows :
(1) The energy, in which the river water entrains bay-seawater, consists of kinetic energy and potential
energy of the river water following into the bay. The former is evaluated by densimetoric Froude number
of the river water, and the latter is evaluated by the water-level difference of bay and river.
(2) The effect of the water-level difference of bay and river on entraining the seawater in the bay is more
effective as the kinetic energy of river water is smaller.
Phytopigment and organic substance in the sediment of Manila clam culture ground were investigated. Sediments
were collected from the tidal flat of a Manila clam culture ground in Ariake Bay, Kumamoto Prefecture,
Japan. It were detemined that contents of phytopigment (chlorophyll a and phaeo-pigments), organic substance,
protein, crude fat and organic carbon in the sediment. Positive correlations were found between phytopigment
and organic substances (r = 0.951), and protein (r = 0.946), and crude fat (r = 0.955) and organic carbon (r =
0.979) in the sediment. Fine particles of the sediment contained higher levels of phytopigment, protein and
organic carbon. These results suggest that phytopigment quantity in the sediment may be good index for the food
environment of the culture ground of Manila clam. Phytopigment contained digestive diverticula and glycogen
included foot of Manila clam which were fed fine particles of sediment were also determined. Phytopigment
contained digestive diverticula and glycogen of Manila clam increased with feeding fine particles of sediment.
These results suggest that fine particles of sediment included phytopigment may be suitable food sources for the
Floating artificial reef (FAR) was adopted as one of the business items of coastal fishing ground improvement
and development project (CFGIDP) in 1994, in Japan. Therefor, the FAR should be designed based on design
guidelines of CFGIDP.
In this paper, the method, which calculates the mooring line tension by the division of the line, is shown. And
mooring line tension of the floating fish reef constructed in Kochi prefecture (KUROBOKU No. 1) is calculated by
the both two techniques and these results are compared.