Forming and Maintaining Mechanism of Tidal Flat in Large River Mouth

(1)吉野河地形年际变化分析利用航片、陆地卫星资料和海底探测资料研究了吉野河口附近地形的年际变化特征。20世纪70年代末，由于S的治理，河口沙洲趋于稳定。同时，对大洪水引起的地形变化也进行了数值模拟研究。(2)吉野河滩底栖动物的特性；调查了河蟹(Uca属)的生态与水力和泥沙特性的关系。(3)交替沙洲上的植物群落；对吉野河形成的两个相邻的交错沙洲进行了全面的植被调查。制作了详细的植被图，考察了前期河流过程对植物群落的影响。(4)泥沙输移的基础研究，半理论研究了泥沙粒径分布对屈服值和泥床临界剪切强度的影响。通过水槽试验，研究了有植被动床的推移质输沙率。

(1) Analysis of annual ahange of topography in the Yoshino river ; The characteristics of the annual topography change in the vicinity of the Yoshino river mouth was investigated using aerial photos, LANDSAT data and bottom sounding data. The river mouth bar has been going to become stable because of the control of dredging river graver after the end of 1970's. The topography change due to a large flood was also investigated using numerical simulations.(2) Properties of benthic animals in the Yoshio river flat ; Inhabitant surveys of fiddler crabs have been conducted and investigated the relation between ecology of crabs (genus Uca) and hydraulic and mud Property.(3) Plant colonies on alternating bars ; A full vegetation survey was carried out on two neighoring alternating bars formed in the Yoshino river. Detailed vegetation maps were made and investigated the influence of prior fluvial process on plant colonies.(4) Basic researches on sediment transport ; Influence of particle size distribution on yield value and critical shear atress of mud bed were investigated semi-theoretically. And bed load rate on movable bed with vegetation were investigated in a flume test.