Longitudinal profiles of most Japanese rivers which are today not at grade can be described by either exponential or power functions. The differences in fluvial processes should reflect the differences in best fit function. In order to clarify the downstream changes in fluvial processes of alluvial river, the downstream changes in the relationships between characteristics of grain size distribution and tractive force, and between tractive force and channel slope were examined for the five rivers in the Kanto plain, central Japan. The composition of channel sediment was separated into several log-normally distributed populations at each sampling point of the river beds. The A-population which is the coarsest size in the separated populations is interpreted to be tractional load, and its size depends on the tractive force which is strongly affected by the channel slope. For the river expressed by an exponential function, the A-population having the grain size of -7 to -6 phi disappears abruptly with the decrease in channel slope in the middle reach. In contrast, for the river expressed by a power function, the A-population having the grain size of -7 to -6 phi is distributed down to near the river mouth, because the decreases both in the curvature and slope of longitudinal profile are small. The downstream limit of the depositional area of the A-population having the grain size of -7 to -6 phi corresponds to the position where the tractive force markedly decreases associated with the decrease in slope along the course of a river. At these positions, the values of the first derivative of the functions best fitting the profiles show about 1/1000 for five rivers. These positions migrate downstream when the best fit function type changes from exponential to power due to the difference in their mathematical characteristics. The distributions of grain size along the middle reach of an alluvial river show the characteristics peculiar to the best fit function type of river profile governing the downstream changes in hydraulic conditions. This implies that both the fluvial processes and the development of the fluvial landforms can be evaluated from the morphological properties of the longitudinal profiles; the best fit function type and the curvature.
An attempt to explain the agricultural land use of an equatorial region around the highland lakes in the southern marginal zone of the Padang (Minangkabau) Highlands, the Province of West Sumatra, was made through both physical and socio-economic approaches. In addition to quantitative analyses of the land use situation in the mid-1980's, the relationship between the dynamics of land use and the changes in socio-economic conditions since the early 20th century was investigated. The principal point of the results of these analyses is that the choice of crops for an upland field was related to transportation and road conditions, and topographic features. We concluded that the inhabitants there responded promptly and rationally to changes in socio-economic conditions including those occasioned by governmental policies. Their positive attitude towards a market economy since the 1920's has been particularly noticeable in a physical environment which is unfavourable for rice production. The development of a road network played a major role in the penetration of a market economy.
This paper first classifies agricultural land use patterns by examining the form and origin of human settlements, agricultural land use components, and their spatial arrangement around settlements or farmhouses, based on previous empirical studies of the lower Asama Volcano. The paper then analyzes the distribution of agricultural land use patterns on the principal lower volcanic slopes in Central Japan. Low-altitude agricultural land use pattern (Type A), characterized by the combination of rice cultivation with fruit or vegetable production, dominates on the lowest part of the volcanic slopes where water is easily available from adjoining rivers, springs, and ponds. The Type A pattern prevails in the zone below 700 meters in altitude. Mid-altitude agricultural land use pattern (Type B) is characterized by variegated land use components including rice, fruits, vegetables, industrial crops, fodder crops, flowers, and seedlings. The Type B pattern dominates in the middle part of the volcanic slopes with an altitude below 1, 000 meters where water is not easily available. High-altitude agricultural land use pattern (Type C), consisting mainly of vegetables, fodder crops, flowers, and seedlings, is predominant in the highest part of the lower volcanic slopes which corresponds to a cool highland climate. The Type C pattern can be divided into two sub-types according to the form of settlement. Among Type C pattern, the dispersed settlement type (Type C 1) generally reflects the characteristics of the agricultural land use patterns found in the newly reclaimed land represented by the reclamation settle-ments of the post-World War II era. Vegetable production and viable dairy farming prevail in Type C 1 settlements. On the other hand, the agglomerated settlement type (Type C 2) represents the characteristics of the agricultural land use patterns found in the high-altitude old settle-ments, where farm households attained large-scale vegetable production after World War II. In general, the Type C pattern dominates in the zone between 900 and 1, 400 meters in altitude. Vertical zonation of agricultural land use patterns, which was clarified on the lower Asama Volcano in previous studies, is the common basic feature of the larger volcanic areas in Central Japan. This is due to the similarities of both physical conditions, e.g., water facilities, tempera-ture, topography (relief), and soil, and socio-economic conditions, e.g., the distribution of settlements by attribute and altitude, traffic facilities, and the distribution of national forests or common lands that could be used for the enlargement of farmland, in addition to the similar processes of historical development on the principal lower volcanic slopes in Central Japan.
Motorization in Japan has been developing since the 1960's and presently shows no signs of decline. Increasingly significant portions of the population are now concentrated in the large urban areas centering around Tokyo, while the surrounding residential areas have expanded concentrically outward. Meanwhile agricultural areas, mountain and fishing villages, and areas with declining industries present conspicuous signs of population decline. With regard to the ratios of transportation means for commuting, and the spreading of privately-owned cars per household of the administrative divisions: wards, cities, and prefectures of Japan, based on the 1980 national census, have identified regional patterns and trends. The areas with higher ratios of commuters by public transportation than by privately-owned cars are limited to only the two metropolitan areas of Tokyo and Osaka and the central cities of the wider region constituted of several prefectures: Sapporo, Sendai, Nagoya, Hiroshima, Kita-Kyushu and Fukuoka and its surrounding cities. The residential suburbs of Tokyo and Osaka display a high-commuting ratio by public transportation and a low-spreading ratio of automobiles per household. The automobile was found to be the most frequent transportation means for commuting in Japanese cities except in the Tokyo and Osaka metropolitan areas. The central part of Japan, covering Chubu and northern Kanto areas, represents an especially high commuting by car ratio and a high spreading ratio of privately-owned cars. These findings reflect the fact that traffic congestion and the lack of parking space in large metropolitan areas work as factors inhibiting commuting by car and car ownership. Consequently, a considerable life-style difference has been confirmed between large city areas, in which commuting by public transportation is common, and the medium and small cities more distant from large metropolises, agricultural areas, and mountain and fishing villages, in all of which commuting by car is more popular and common. Wide-spread use of automobiles as the primary mode of transportation not only provides convenience, but also generates various problems such as the decline of public transportation and additional restriction on an already partially-immobilized segment of the general population, that is the physically-challenged and the elderly.