Ariake Sea Research Project, Saga University
For more details, please refer Final outcome report(pdf file).
Our group got three following conclusions
For the numerical modeling of the suspended sediment transport,mapping
of the resuspention coefficent and measureing of the settling veolocity
of the suspended sediment were performed.
The resuspention coefficent in the Ariake Sea could estimated by the
clay content,dry density and vane share st rength of the bottom sediment.
Settling velocity of susupended sediment in the Ishaya Bay,Ariake Sea
were propotinal to the 0.77 power of the concentration of susupended
solid.
The macrofauna of three esturaine tidal flat areas at the mouth of the
Chikugo River,Rokkaku River and Shiota River in the inner
part of Ariake Bay is described.Sampling was done from a boat during
high tide using a Smith -McCintyre grab sampler at 11 station in each
area .Multivariate analyses show that community structure differed
siginificantly between the dital flat. The distrobution of endangered
spceies and invasive species also diffrent between River flats, and
those species occured mainley in the mudflats of the Rokkaku River and/
or Shiota River estuaries. Differences in sediment grain size would be
factor of the diffrences in the macrofauna and the distribution of
endangered and invasive species among the tidal flats.
Influence of Extracellular Polymeric Substances originated from benthic
algae on particle aggregation and sedimentary stabilization in Ariake
Sea was investigated through laboratory experiment. Extracellar
polymeric substances in the lyophilized sediment were isolated as
colloidal carbohydrate fraction. The influence of the polymeric
substances on particle aggregation and sedimentary stabilization was
experimentally examined through rheological measurement. Evaluate of
rheological properties of polymeric subustances solution and
sedimentslurry with polymeric sibistances ,calcium ion were carried out
using a shear rate chargeable rehometer .Evaluate of rheological
properties of polymeric substances solution and sediment slurry with
polymeric substances ,calcium ion were carried out using a shear rate
changeable rehometer . This aqueous solution of polymeric substances
solution behave as Bingham fluids, the shear stress increase with
elapsed time. It would be most like due to hydration. The sea sediment
slurry with polymeric substances behave as non-Bingham fluids. The
stress-strain hysteresis loop width predicts the interaction of sediment
and polymeric substances. Polymeric substances enhance of sediment
stabilization, the effect is greatly improve by calcium ion.
under construction
Contributions of pollutant loads from each river basin along the Ariake Sea are estimated by using runoff and pollutant load models of all class A rivers and Isahaya reclamation reservoir. Considerations for balances of water and substances by field observation clarify problems of unit load method. Seasonal variation in the wind field over the Ariake Sea was investigated and its influence on the current distribution of the Ariake Sea was evaluated. Seasonal variation in hydrography, sediment transport and transparency in the Ariake Sea was calculated with a 3D sediment transport model based on the FVCOM. The influence of the existence of the Isahaya dike on sediment transport and transparency of the Ariake Sea was evaluated with the same model. Though some technical problems are remaining, a high resolution 3D ecosystem model of the Ariake Sea was constructed to evaluate the influence of the open gates in the Isahaya dike. Field survey data were analyzed and it was shown that the suspended sediments in the Isahaya Bay were transported toward the bay head in the autumn non-stratified period. Moreover field and laboratory experiments on the vertical distribution and cell division cycle of Chattonella were performed. Finally all the results of the 5 years research project was generalized and reported at a number of symposiums and workshops.