Forming and Maintaining Mechanism of Tidal Flat in Large River Mouth

(1)吉野川地形年变化分析利用航空照片、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变化特征。70年代末以后，由于疏浚工程的控制，河口拦门沙趋于稳定。利用数值模拟方法研究了大洪水引起的地形变化。(2)吉尾江滩底栖动物的特征对招潮蟹的栖息地进行了调查，研究了招潮蟹的生态与水力和泥质的关系。(3)交错沙洲上的植物群落：对吉野川形成的两个相邻交错沙洲进行了全面的植被调查。制作了详细的植被图，并调查了先前的河流过程对植物群落的影响。(4)泥沙运动基础研究：半理论地研究了颗粒级配对泥床屈服值和临界切应力的影响。通过水槽试验研究了有植被的动床推移质输沙率。

(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.