Paddy fields made on slopes in the form of a series of shelves are called “rice terraces”, or “tanada” in Japanese. These rice terraces are distributed over the whole country except Tokyo, Saitama and Okinawa, and they are particularly concentrated in the Kubiki Hills of Niigata Prefecture, on the Kibi Plateau in Okayama Prefecture and at the foot of the Aso-Kuju Volcanoes in Oita Prefecture. However, farming on these rice terraces has low labor productivity, and with advancement in the age of the farmers in the mountainous areas, it has become difficult for them to continue farming on the rice terraces, and the abandonment of them is now noticeable. Recently, however, the rice terraces have come to be viewed in a different light in their ability to control soil erosion and floods, along with the beautiful landscape which gives amenity and nostalgia to the people. For this report, three settlements endeavoring to sustain the rice terraces-namely, Shirayone, Wazima City in Ishikawa Prefecture, Maruyama, Kiwa-cho in Mie Prefecture, and Ohaka, Chuo-cho in Okayama Prefecture-are selected as the study areas. In Shirayone, Wazima City, the rice terraces are located along the tourist route. Thus, with support from the tourist industry, other economic organizations and the cultivation subsidies from the local government, the rice terraces has long been preserved. In Maruyama, Kiwa-cho, the local government has promulgated the regulations for the sustenance of the rice terraces on the one hand and has employed the farmers to restore the devastated rice terraces on the other hand together with their maintenance and management. In Ohaka, Chuo-cho, the size of operational holdings is relatively large and the agricultural co-operative association is encouraging the farmers towards sustenance of the rice terraces through organic farming and by farming without agricultural chemicals, thus adding value to the rice produced. Now, comparing the measures developed in these three settlements for the sustenance of rice terraces with one another, the following has been found. (1) In the case of a farm household of a small size of operational holdings, it has become difficult to maintain farming the rice terraces unless support of urban inhabitants is given or the government grants income compensation directly to the farm households. (2) In the case of a relatively large size of operational holdings, it is necessary for the sustaining of the rice terraces to increase the value added to the rice produced commensurate with the labor force invested, and one of such ways is the organic farming of paddy rice without agricultural chemicals. (3) As aged farmers retire from farming the rice terraces, the difficulty in securing people who will engage in farming will become a big problem in promoting the sustainability of the rice terraces. To solve this problem, it will be necessary to seriously face the problem of securing the labor force by recruiting farmers from among retired people living on pensions, weekend farmers and voluntary urban inhabitants.
Based on the direct observation of two rock avalanches occurred in the snow-melt seasons of 1993 and 1995 at Karasawa Cirque in Mt. Hotaka-dake (3, 190 m a.s.l., 36°15' N, 137°39' E), central Japan, the characteristics of rock-avalanche processes were elucidated in detail. Observed rock avalanches occurred after the snow on rock walls melted. Exsistence of seasonal frozen layers in the bedrocks was considered to play an important role of the occurrence of rock avalanches. The frozen layers had close relation with seasonal freeze-thaw actions. Moreover, water-regime changes in the rock walls were also controlled by the frozen layers as impermeable layers in and/ or after heavy rains. Rock masses separated from rock walls fell and/or jumped down to snow-covered talus slopes and, after being mixed up much snow, flowed on the slopes with reducing its speed. Finally, the rock masses and snow formed dirty avalanche tongues in deposition areas. In the rock avalanche occurred on July 10th, 1993, its travel distance and duration of processes indicate the veocity of about 70 km/h in average and about 100 km/h in the maximum. Volume of debris of a rock avalanche with frequency of once in tens of years is more than 103 m3, and one with frequency of once in several years is about 102 m3. Relative vertical mass transfer in unit area, which is estimated for quantitative comparison of process intensity, has the rate of 106 t · m/ km2 ·year. Rock avalanches occur in a cyclic pattern which fundamentally depends on the structure of rock walls. Low magnitude rockfalls and small rock avalanches occur on the denselyjointed rock walls under the control of diurnal freeze-thaw actions and water-regime change affected by intense rainfall. Its occurrence is more frequent than once in several years. Erosion on densely jointed walls induces gradual instabilization of neighboring sparselyjointed walls, and finally provokes higher magnitude rock avalanches there. The latter takes place less frequent than once in several decades.
Many old documents show that the Ainu in the Edo period (1603-1867), who were fishers, hunters and gatherers, were a migratory people. It is also widely accepted that the Ainu moved seasonally from their home residences. This probably indicates that the residents of these settlements were relatively stable. But a detailed analysis of other documents shows that two types of mobility were found in Ainu society : inter-settlement movement of households and inter-household movement of the inhabitants. In the Takashima district during the years 1834-1871, the high death rate was the main cause for inter-household movement of the inhabitants. This type of mobility is entitled “Coping Mobility”. The purpose of this paper is to show that during the years 1848-1858 the composition of households in the Nemuro district of Hokkaido varied as a result of inter-household movement of its members, and the main cause for the high mobility was not the high death rate but the high divorce rate. In the Nemuro district, the population of the Ainu decreased dramatically between 1848 and 1852, and then it increased between 1852 and 1858 (Figs. 1 and 2). Their life had already changed depending less on fishing, hunting, and gathering, under the influence of the Wajin. Most permanent residences were located within the same settlements (Fig. 3), but many resident members moved between households (Fig. 4). The number of persons per 100 inhabitants during a 10-year period who moved between households was very large, especially in the Nemuro district and also in the Takashima and Monbetsu districts. But the number was much smaller in the Mitsuishi and Shizunai districts and the southwestern part of Sakhalin (Table 1). The stability of the household members was much lower in the Nemuro, Takashima and Monbetsu districts than in the Shizunai district and the southwestern part of Sakhalin (Fig. 5). Four factors were recognized as main causes for the movement of household members : (1) the death of a spouse, (2) the death of someone other than a spouse, (3) the divorce of amarried couple, and (4) the separation of someone other than a spouse (Fig.8). About 81% (510/631) of the total number of persons who moved between households did so owing to these four reasons. When we include the cases where people moved for two or more reasons, about 68% (349/510) moved because of divorce, and about 94% (481/510) moved because of the divorce and/or the death of a spouse. Persons who moved between households owing to divorce moved individually in most cases, rarely together. When they moved together, they were in most cases unmarried children and their mother (Table 5). About 54 % of the men divorced between the ages of 20 and 34, and about 62% of the women divorced between the ages of 15 and 34 (Fig. 9). The rate of divorce was much higher in the Nemuro district than in the Takashima, Monbetsu, and Shizunai districts and in the southwestern part of Sakhalin (Table 7). The typical pattern of mobility among households is as follows. After a married couple divorced, the former wife moved to another household, usually by herself, sometimes the children would accompany her (sometimes the children would move with the father). In many cases the divorced persons moved to another household to remarry. When they did not move for marriage purposes, they moved to the households where their siblings, fathers and/ or mothers dwelled. This was the first move for the unmarried children. When the unmarried children grew up, they might move to another household for their own marriage. This would be their second move. Then if they divorced, they would move to a third household. In the Nemuro district the inter-household movement of the inhabitants is regarded to have been caused by the high divorce rate. This type of mobility is entitled “Preparative Mobility”.
The objective of this study is to examine the centrality of Sendai City in the regional urban system in the Tohoku district through the analysis of agglomeration processes and locational patterns of lodging facilities and their operations in urban areas. Japanese lodging facilities can be divided into two main categories : Japanese style lodging, called ryokans, and western style hotels. Most lodging facilities in the Tohoku district were composed of ryokans in the 1960s. When the size and number of hotels began to increase rapidly in Sendai in the early 1970s, western style hotels multiplied in the Tohoku district, following the trend that occurred in the main metropolitan regions of Tokyo-Yokohama and Kyoto-Osaka-Kobe. The increase in the number of hotels in Sendai, as well as in Sapporo, Hiroshima and Fukuoka in this period, signifies that hotel construction diffused from the largest cities to regional central cities following the national urban hierarchy. After the first increase in hotels in Sendai, hotel construction diffused to prefectural capitals and other major cities in the Tohoku district. This agglomeration process reflected the spatio-temporal differences among the cities. Each city is different in terms of population size and growth, urban functions and access to major transportation networks. In Morioka City, for example, the number of hotels increased rapidly in the early 1980s, after the opening of the Tohoku-Shinkansen (Tokyo-Morioka), which connected the northern Tohoku district with Sendai or Tokyo. The opening of the Tohoku-Shinkansen also resulted in the second rapid hotel increase in Sendai. While the number of ryokans in urban areas has remained stable or has decreased since the 1970s in the Tohoku district, locational patterns of ryokans and hotels have changed considerably, especially in Sendai. In 1970, the majority of hotels were ryokans, which were densely located, traditionally in the CBD and its surrounding areas in Sendai. However, after the first and second phase of new hotel construction, ryokans located in the CBD decreased rapidly because of rising land prices and the construction of high-rise buildings. As a result, in 1996 the western style hotels were clustered in the CBD, while ryokans remained dispersedly in the surrounding CBD areas. However, few hotels were located in the core of Sendai's CBD near the station because this area had already been developed before the first increase in the number of hotels. The rapid and large-scale increase in the number of hotels in Sendai was a result of an increase in the range of services that they provided. Most of the hotels constructed during the first period of increase were commercial hotels catering to the needs of tourists. Therefore, the main function of their hotels was lodging. However, many hotels that were built during the second period of increase were equipped with convention facilities. Thus, hotel operations started to revolve around banquets, conventions and restaurant dining. These operations, especially large-scale convention halls, also attracted business customers from Tokyo and the Tohoku district. The agglomeration processes of lodging facilities reflect the regional urban system and urban structure, and the functions of lodging facilities signify the geographical characteristics and the centrality of Sendai.
A doughnut-shaped pattern of spatial distribution of small earthquakes appeared before an M5.8 earthquake which occurred in eastern Yamanashi on 6 March 1996. The pattern was observed in the conspicuous activity which started about two months before the M5.8 earthquake. The central part of the pattern, where remained as a gap during the active period, was filled with aftershocks of the earthquake on 6 March. The activity before the M5.8 earthquake was an abnormal one in a sense that CHASE (Yoshida et al., 1996) showed such a large value that exceeds three times of the standard deviation. We expect that watching change of seismicity by making a CHASE-plot is useful for estimating occurrence of major earthquakes, although we should examine the practicality and applicability of the method further using the data of much longer period and in other regions.
Geographers and environmental scientists prefer to construct Spatial Information System (SIS) decision support from the smallest possible data. This is due to the considerable cost of ground-based surveys for data collection. This paper extends on the work of (Kirkby, 1994; Eklund et al., 1995) and reports on the use of machine learning classifiers to obtain the minimum sample size for ground-based data surveys. The study proposes a method to assess ground-based data collection using machine learning classifiers. In this domain, the inductive learning program C4.5 (Quinlan, 1993) was used to verify that a high performance classifier, better than 95 % classification accuracy on unseen data, can be constructed using 235 sample points in the study area. We compare this result to the magnitude of sample sizes required for back-propagation neural networks (NN) and instance-based learning (IBL) with the same classification accuracy on unseen data. We examine the reasons and implications for these variations for classification accuracy in this domain.
There are many farm ponds in the western part of Japan and they play important and essential roles in rice field cultivation. Of the farm ponds in Hyogo Prefecture, 1372 were damaged by Hyogo-ken Nanbu Earthquake in 1995. The author aimed to clarify the features of the damaged farm ponds from an impounded water level of them. The results are as follows. In the case of valley closed ponds (tani-ike), ponds of high water level were hardly damaged and those of low water level were heavily damaged. In the case of flat ponds (sara-ike), ponds of high water level were heavily damaged and those of low water level were hardly damaged. In both cases of valley closed ponds and flat ponds, ponds of middle water level were slightly damaged. The farm ponds located just near fault lines and those not repaired for more than 100 years were heavily damaged, although their water levels were in safe rangefor the reason above mentioned. Also the farm ponds repaired or built in recent years were hardly damaged, although their water levels were in dangerous range. Many valley closed ponds were damaged, because their water levels were decreased under the influence of drought of previous summer.