Interrelation between hydrogeomorphic and vegetative processes in rivers.

1)河床长期变化分析：以日本四国吉野河为例，构建了近40年河床几何数据库。个体测量的截面形状用固定的101个点表示。利用经验正交函数法对其地貌过程进行了分析。研究结果表明，该地区存在明显的层积作用，并确定了层积作用的主要模式。2)植被与水文地貌河流调查与分析：对中、吉野河进行了广泛的沙洲植被调查。此外，还通过航拍照片观察了河流植被的定殖成功。定植性状与河流的历史水文地貌条件有定量关系。3)交替沙洲植被网格化图的数值复制：利用低空航拍技术对吉野河下游河段交替沙洲进行实地调查，绘制了交替沙洲植被网格化详细图。应用偏好曲线模型和神经网络模型，从生境物理属性判断网格区优势植被类型。两种模型的精度相近，略高于70%，略低于70%，但生成的地图存在显著差异。4)河床变化模拟模型的完善：通过实验明确了流经植被区域的泥沙悬浮机理，并建立了其模拟模型。在数值模拟的基础上，研究了自成流和混沙互变沙坝的特征。

1) Analysis of long-term riverbed variation : Regard to the Yoshino River, Shikoku, Japan, a data base of riverbed geometry was composed, with respect to the past 40 years. The cross-sectional shapes of individual measuring were represented by fixed 101 points. The geomorphic process was analised with the aid of empirical orthogonal function method. As a result, remarkable bed aggradation was observed and its major modes were identified.2) Vegetative and hydro-geomorphic river survey and analysis : Regarding to the Naka and Yoshino River, vegetation survey on sediment bars was were widely carried out. In addition, colonization success of riverine vegetation was observed referring to aerial photographs. Colonization traits were quantitatively related to historical hydro-geomorphic conditions of the reivers.3) Numerical reproduction of meshed vegetation maps of alternate bars : Detailed meshed vegetation maps of alternate bars formed in a downstream reach of the Yoshino River were produced by field surveys with the aid of an low aerial photography technique. A preference curve model and a neural network model were applied to judge dominant vegetation types of mesh areas from physical habitat attributes. The both models showed similar accuracy of slightly higher and lower than 70 %, however, significant difference was found in the resultant maps.4) Improvement of simulation model for riverbed variation : Mechanism of sediment suspension in flows passing vegetated areas was experimentally clarified, and its simulation model was developed. In addition, characteristics of self-formed streams and alternate bars of mixed sediment were investigated based on numerical simulation.