The theoretical formula of three stratified interfacial long waves are deduced and its validity is verified by
The three stratified interfacial long waves consist of two modes that are Mode I and Mode II. These waves
velocity are expressed cI and cII in equation (1') respectively. The wave numbers of these waves are expressed
k1 and k2 in equation (3). These stratified interfacial wave profiles of first and second interface are expressed
ζI1, ζI2, ζII1 and ζII2 in equation (8) respectively. The water particle velocities of these waves in first, second
and third stratified layers are expressed uI1, uI2, uI3, uII1, uII2 and uII3 in equation (9) respectively. These relations
between the profiles and the velocities are shown in figure 2.
This paper presents details of a second order accurate Godunov-type numerical model of the two-dimensional
shallow water equations and shows the application of the model to flow in a vertical sIot fishway. The
model employs Roe's flux function for the convection tems and a non-linear slope limiter to prevent unwanted
spurious oscillations. The model is also based on quadtree grids that adapt to inherent flow parameters, such as
Three test cases are demonstrated using a typical vertical slot fishway. The first test case uses relative
coarse numerical grids and the second uses fine grids. The third one uses solutio-adaptive grids. Comparing the
results between the first and second cases, it is shown that the results largely depends on the size of grids in
interior flow region, even though the flow boundaries are fitted correctly by quadtree grids. Through the comparison
between the results of second and third cases, the advantage of solutio-adaptive grids is demonstrated.
This paper reports on the development and testing of the new type seawater intake works using wave energy.
The one is 'the seawater intake works with cylindrical holes',. one of the most important characteristics of the
works is to having the aeration ability for the improvement of aquatic environment. A hydraulic model test on the
works was conducted in the basin and in the channel. The adequate specifications of the works had to be found by
trial and error. According to the various studies, the works has proved to be good enough. The main results are as
follows : (1) The works with 10 meters length has the ability of training seawater 40,000m3/day when the coastal
waves has the condition that is head incident, 0.5 meter significant wave height and 4 seconds wave period ; (2) In
case of the tide level locates the quarter diameter below from the center of the cylindrical hole ; the works functions
the most effectively ; (3) The reflection coefficient is 0.63 to 0.65 ; the transmission coefficient is no
detected in random waves ; and (4) When the ceiling slab cIoses the wave chamber, the air duct with 0.5 to 1
percent of the ceiling slab area must be constructed to prevent air compression.
Propagation of the seagrass, Zostera marina, was examined by using artificial seeding methods on polypropylene
mats named as a sediment stabilizer mat (SS-mat) used to decreasing sediment disturbance on the sand
substratum off Kushiki, Naruto, Tokushima prefecture, eastem Seto Inland Sea. SS-mats (1m x 1m, 4cm, 23 and
31kg of weights) were made of pemeable meshes. The first experiment was started in autumn, 1995 and the
second experiment in autumn, 1996. Plants of Z. marina, seeded on to the mats, grew successfully for four years
even under a harsh environmental condition of high wave height and fluctuations of the sand bottom level in the
winter season. In both experiments, the shoot density on the SS-mats was observed to decrease after the maximum
number of individual shoots (50-60 shoots/m2) in the first summer season to several shoots/m2 in the 2nd
and 3rd summer seasons. Z. marina plants made reproductive flowering shoots on the SS-mats since 2nd spring
maturing period. The SS-mats were useful in germination of seed and growth of seedlings for Z. marina, but not
useful for the survival of adult plants due to the lack of sand accumulation on the mats. Such long term monitoring
of continuous growth of Z. marina plants on the SS-mats is required for promoting the methodoIogy of establishing
sea grass beds restoration.
This study examined the effects of bottom disturbance associated with wave action on the burrowing behaviors
of the surf clam Mactra chinensis (shell length = 28.5 - 85.0mm) using a vertical circulating water channel.
The burrowing speed of the clam tended to increase with shell length and Shields number as an index of bottom
disturbance regardless of burrowing posture toward water flow. The relationship between the burrowing speed
(V : mm/s), Shell length (L : mm) and Shields number (ψ) was described as V=0.022L+5.989ψ. A large number
of the clams apparently burrowed with orienting their lateral toward the flow. The critical conditions when the
clams could not burrow into the sand and would be washed out of the sand by bottom disturbance were shown as
functions of the shell length and Shields number with ψ =3.087×10-4L＋0.081 and ψ=0.004L＋0.099, respectively.
The critical Shields number to wash the clams out of the sand corresponded to that of shallower limit of
water depth in the clam habitat.
The mean fish body length, the fish body weight and cultured fish number per unit volume of the pen are
estimated from the practical fish culture data of yellowtail, sea bream and so on. Depending on these data, the
relationship between the body length and body weight and numbers of cultured fish per unit volume of the pen
are clarified. Moreover the dissolved oxygen consumption by fish per unit volume of the pen are discussed.