Forming and Maintaining Mechanism of Tidal Flat in Large River Mouth

(1)吉野河地形年变化分析；利用航空影像、LANDSAT资料和海底测深资料，研究了吉野河口附近地形的年变化特征。20世纪70年代末以来，由于疏浚河道掘进机的控制，河口坝已趋于稳定。利用数值模拟方法研究了大洪水对地形的影响。(2)吉夫河段底栖动物特征；本文对招潮蟹（招潮蟹属）进行了生境调查，探讨了招潮蟹生态与水力、泥浆性质的关系。(3)交替栏上的菌落；在吉野河形成的两个相邻的交替沙洲上进行了全面的植被调查。绘制了详细的植被图，并研究了前期河流过程对植物群落的影响。(4)输沙基础研究；从半理论的角度研究了粒径分布对泥床屈服值和临界剪切应力的影响。通过水槽试验研究了带植被的活动河床的河床荷载率。

(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.