Tenryu River Research Articles

MUSICAL INSTRUMENT INDUSTRY IN HAMAMATSU

Hamamatsu industrial region which are located in the western part of Shizuoka Prefecture is an old industrial region in the Tokai region. The most important industries of the region are cotton textile, musical instrument and transportation machinery and they are called big-three industries in this region. And the others are fabricated metal, machine tool, timber, dying and food industries. These industries have never developed separately at all, but they have developed in close relationship with each other, and the preceding industry in this region has functioned as leading industry for the birth of new one. The output of the musical instruments in the Hamamatsu region now accounts for 99.5% of piano production and about 80% of organ production in Japan, and such exclusive production of musical instruments in the Hamamatsu region is not accidental even at all, but the localization was sustained by the geographical conditions and the industrial context of the region. The manufacturing of musical instruments in Hamamatsu was started by Torakusu Yamaha. He was born in Wakayama, became a repairman of medical appliances and stayed in Hamamatsu by chance. When he established Yamaha Organ Company in 1888 and began to make organs, there were several favorable conditions for him in Hamamatsu, especially the capitals and the techniques. The capitals offered to him by the entrepreneurs in Hamamatsu were those accumulated in this region through the tea and cotton texitile manufac Luring from the Feudal Days and among the techniques offered were those of the ingravers in Hamamatsu, and of the ship carpenters in Kakezuka, the old harbour of the Hamamatsu clan at the mouth of River Tenryu. Torakushu Yamaha established the Nippon Gakki Company in 1897 and began the production of pianos in 1900. Koichi Kawai who was an engineer, a inventor of piano action and also a head of the piano action in Nippon Gakki Co. established Kawai Gakki Company in 1927 and since then the production of musical instruments in Hamamatsu has developed. After the Second World War, the new factories of musical instruments have increased year by year. They reached 32 factories in 1961 (16 in 1950), and they produced mainly pianos. The special features of the production after the War are the increase of parts-making works of small scale and piano factories. Nippon Gakki and Kawai Gakki also developed in close connection with such parts-making works. The plywood is very important material for the production of organ and piano, and plywood factory was already established in the Hamamatsu region in 1908 by Nippon Gakki. The facilities and the techniques of plywood production has given birth to the woody propeller production in 1921 and this has once more given birth to the metallic propeller production since 1931. These propeller industry by Nippon Gakki has not only become the core of the munition industry in Hamamatsu during the Second World War, but also the foundation of the transportation machinery industry with main production of motor bicycles and moter boats after the War.

A STUDY ON THE AEOLIAN BED-FORMS IN ENSHUNADA BEACH, SHIZUOKA PREFECTURE, CENTRAL JAPAN-THEIR CONFIGURATIONS AND CRITERIA OF FORMATION

Enshunada beach located in Shizuoka Prefecture, Central Japan, is divided into two similar arcs by the advancement of the delta of River Tenryu (Fig. 1). In this region, the weather is so fine that the surface of beaches is dry in winter. Sand drift occurs by strong westerly to northwesterly wind which is prevailing in winter (Fig. 2). Various aeolian bed-forms are formed on the backshores in this beach (Fig. 3). These aeolian bed-forms are classified into sand ripples (Photo. 1(a)), granule ripples (Photo. 1 (b)), and dunes (Photo. 1 (c) and (d)) according to the wave-length. Regardless of size of the wave-length, aeolian bed-forms have two characteristics. One is that they have transverse ridges against the wind direction, and the other is that they have a gentle slope in the windward and a steeper slope in the leeward (Fig. 4). In dunes, two kinds of the bed-forms are observed; one has the smooth curve all over a dune from windward slope to leeward slope (Photo. 1 (c)), and the other has the straight and steeper slope, which is called “slip face” in the leeward (Photo. 1 (d)). The former is named “wavy dune”, and the latter is named “dune with slip face” by the author. In addition to ripples and dunes, two plane forms are observed. They are “flat bed” which involve large amount of sand drift, and “plane bed” which involve the least amount of sand drift. Bed-fours observed in this region are classified into following six types by their wave-lengths and the characteristics of configulations: “plane bed”, “sand ripples”, “granule ripples”, “wavy dunes”, “dunes with slip face”, and “flat bed”. Sand ripples are generally formed everywhere in these beaches and granule ripples are observed on backshores of Nakatajima where bed materials contain granule and coarse sand (Table 2). In many cases, dunes are formed on the backshores of eastern districts in both arcs. For the formation of the dunes, a long fetch of wind and a supply of sand are neccessary. In the eastern districts, the direction of prevailling wind is parallel with the strike of beach lines (Table 1). Because the mean diameter of bed materials varies from place to place, there are some differences in wind velocity (V1.0), which corresponds to the formation of sand ripples. As the mean diameter is larger, V1.0 is slightly larger in Nakatajima than in any other places. The transformation of the dune profiles were measured by leveling on Dec. 6, 8, and 14, 1974 in Chihama (Fig. 6 and Table 3). The wave-length change is generally small. The wave-height change is clearly recongnized and it is classified into following three types: Type 1 There is no distinct change of wave-height, Type 2 Wave-heights increase markedly, and Type 3 Wave-heights decrease prominently. There is a good correlation among these three types of changing dune profile, the wind velocity (V1, 0), and the condition of formation or disappearance of ripples (Table 4). When the wind velocity is small, the dune profile change becomes the type 1 and the ripples are formed clearly. When the wind velocity is medium, the dune profile change becomes the type 2 and the ripples disappeare. When the wind velocity is large, the dune profile change becomes type 3 and the ripples completely disappeare. Thus it seems that the types 1, 2, and 3 correspond to the cases of ripple formation, dune formation, and flat bed formation respectively. Aeolian bed-forms are the results of processes occuring at the interface between the sand bed and air flow.

THE PHYSICAL CHANGE OF PADDY FIELDS AND THE LOCAL GOVERNMENT POLICIES IN THE DOWNSTREAM AREA OF THE TENRYU RIVER

The purpose of this paper is to delineate some characteristics of recent changes of agric-ulture in the Hirose section of Toyooka village and the Ryuchi section of Hamakita City, which are both in Shizuoka Prefecture. It should be noted that the physical location of these two areas are in the downstream region of the Tenryu River. An important given factor in this study is the central government's allotment quota of rice growing acreages. Constructions of two large scale dams, the one installed at Sakuma in 1956 and the other at Akiba in 1957, in the upperstream of the Tenryu reduced the supply of materials such as gravels, sands, and silts to the downstream, in comparison to the supply obtained prior to construction. One results was the lowering of the riverbed. Another conributing factor was the removal of existing river supplied materials for urban construction in recent years. The overall result consisted of lowering of the ground water and poorly preserved water condi-tions in the paddy fields of the nearby areas. To somewhat alleviate this problem, some local governments introduced a “Paddy Field Improvement Project”, which called for replacement of gravels immediately below the top soils by old alluvial soils, obtained from the slopes of hills nearby. Many factors have to be taken into account when considering actions taken by individual farmers and/or groups of farmers in relation to decisions made by the local governments. Some of these factors are; (1) the size of the area under cultivation ; (2) the incentive of the individual farmer; (3) urban influence. For example ; Ryuchi is closer to Hamamatsu than Hirose; and (4) degree of enthusiasm and capital investment in administrative pro-grams by local governments. In Hirose, the village administration originated and utilized to a large extent, the “Paddy Field Improvement Project”, which brought increased rice production per unit of land and previous unused land under cultivation. As one result of the above, it was assumed that number of owner-farmers (whose sole occupation is farming) would increase as opposed to the previous situation. Taking into consideration of political factors and administration enthusiasm, this village would be used as a model for other local governments. In Ryuchi, on the other hand, the “Paddy Field Improvement Project” fell behind the expectations of the local government, because of lack of cooperation between the local government and the farmers. The allotment quota in Ryuchi was easily achieved, be-cause unused acreage has increased in recent years. The lack of a choice of local impro-vement programs resulted in the diversification of agriculture by individual and groups of farmers. One problem, which confronted the agricultural development of Ryuchi, was the urban influence of nearby Hamamatsu City. Many job oppotunities resulted in the break-up of full-time farmers into part-time farmers. The administrative effort of the Toyooka village resulted only in a slight rise in income of farmers. In both areas, if we take full-time farmers, for example, we find that both followed the same process of occupational specialization, due to the overall Japanese economic syst-em. As a result of the above, it can be concluded that local government assistance is limited under the present agricultural system.

REGIONAL STRUCTURE OF THE ELECTRONIC PARTS INDUSTRY IN THE KAMI-INA DISTRICT, NAGANO PREFECTURE

This paper aims at an analysis of the industrial aspect of the regional structure in the case of the Kami-Ina district, Nagano Prefecture, Central Japan, where the electronic parts industry has been developed. The electronic parts industry is labor-intensive, depending much on cheaper labor force. Main factories usually contract a part of the manufacturing processes, mainly those of lower productivity, with many subcontract factories. In this respect, the arrangement of production organization becomes hierarchical, being composed of main factories, branch factories, subcontract factories and housewife-laborers. Spatially speaking, the hierarchical production organization forms a kind of circular structure, that is to say, some of the main factories or finished-goods factories are located in the central urban area of the region and some of the branch factories are located in the intermediate zone, whereas in the surrounding rural areas many subcontract factories are scattered. In respect to the structure of the labor force of the electronic parts industry in this region, female laborers are more numerous than male ones in almost all factories. The larger the scale of the factory is, the younger female laborers work and the smaller the scale of the factory is, the more the housewife-laborers work. Almost all of those who work at home are housewives. In respect to the relationship between the factories and the farm villages, it can be said that larger-scale factories located in the central urban area gather younger laborers from the surrounding farm villages. Small-scale subcontract factories located in the rural areas gather housewife-laborers from smaller farm. In many cases, the seasonal housewife-laborers from larger farms are not employed by small-scale subcontract factories in the rural area.Compared with villages on the terrace of the Tenryu River, the farm villages below the terrace tend to draw more housewife-laborers, of more aged generation in general, for food and wooden-ware industries, decreasing the number of employies in electronic parts industry.

天竜川における水生昆虫群集の構造, biotic indexおよび季節変動

Ecological studies were made of the aquatic insect communities in the Tenryu River, Central Japan, in the summer of 1967, with special reference to their composition, the biotic index calculated according to BECK-TSUDA's method. During the years from 1968 to 1969, the seasonal change of aquatic insect communities and the biotic index were studied in the area of polluted water by wastes from the KP pulp plant located in the upper reach. The results are as follows 1. In July, 1967, the aquatic insect fauna was poor in the Tenryu because of various reasons. The net-spinning caddis-worm Hydropscyche ulmeri was dominant at most stations there. 2. The aquatic insect communities were composed of 20 to 29 in the number of species, of which the maximum numbers attained in May, the minimum in July, at the station Tatsuno-A (relatively clean water) in the samples by using a quadrat (50×50cm). The number of species at Tatsuno-B (150 meters down from the KP pulp plant) was 2 to 4, and that at Shinmachi (2 kilometers down from the same plant) was 8 to 14. 3. The individual numbers and standing crops of many species of aquatic insects became minimum in summer in quadrat samples at Tatsuno-A, and increased from autumn till winter. 4. The seasonal change of the biotic index was 37 to 53 at Tatsuno-A, 3 to 7 at Tatsuno-B, and 12 to 25 at Shinmachi.

中部地方の微小地震活動 (3)

We set up a temporary seismographic network with four stations in the western part of Sizuoka Prefecture, central Japan, for the observation of microearthquakes during the period from July to August in 1970.The results obtained in the observation were as follows; very shallow earthquakes occurred to the east side of the Tenryu river. But in the north-west side of the Median Tectonic Line and in the vicinity of Lake Hamana, many earthquakes were located as deep as Moho discontinuity showing a systematic focal mechanism.These distributions of focal depths were similar to those in Inuyama area where many earthquakes occurred at shallow depths in Mino-Tanba belt and those in Ryoke belt were below the Moho discontinuity.

Analysis of Degradation on Aerial Photographs

This study is the numerical analysis of degration's masses and it's factors. We have obtained the factors of degradation on aerial photographs, and estimated the point rainfall with digital terrain model.We performed a test on this method to the River Tenryu and obtained the satisfactory results.

ON THE DISTRIBUTION OF “SHIMA-BATAKE” (ISLAND-LIKE OR MICRO-BUTTE-LIKE UPLAND FIELD) LANDSCAPE

By “shima-batake” landscape is meant landscape in which upland fields of various shapes, approximately 50-80 cm. above the ground of paddy-fields, are distributed among paddy-Melds, much as micro-buttes are scattered over a plain, or numerous small flat islands are scattered over the sea. In regions where “shima-batake” are densely distributed, there are cases in which the area of upland fields is larger than that of paddy-fields. The purpose of the present paper is to clarify in which regions such landscapes are found. In the first place, after making a detailed inquiry into the relationship between the distribution of “shima-batake” and micro-land forms as well as irrigation in the Hamana and Iwata Plains in the downstream region of the Tenryu River, consideration was given to the origin of “shima-batake.” By a similar method of investigation, inquiry was made into the downstream plains of the Kiso River, the Yahagi River, the Toyo River, the Sagami River, the Kuji River, the Naka River, the Shinano River, the Agano River, the Kariyata River, etc., and also the coastal plains of the Tone River, the Kinu River, and the Naka River, as well as the downstream plains of the Yoro River, the Obitsu River, and the Koito River, on the west coast of the Boso Peninsula, the Kujukuri coastal plain, and two other regions. Approximately 40 years ago, Prof. Glenn T. Trewartha expressed his opinion concerning the “shima-batake” in the downstream plain of the Tenryu River (Annals of American Geographers, Vol. 18, 1928, pp. 127-257). In a recent work, he has expressed the same opinion as before (Japan, a Geography, 1965, p. 652). His opinion is as follows: As a result of the flooding of the Tenryu River, large deposits of detritus were made in the paddy-fields, and the irrigation canals were buried. In their work of restoration following the disaster, the farmers removed the detritus from the paddy-fields and irrigation canals, and piled it up in one part of the paddy-fields, which they later leveled out to make upland fields. These up-land fields formed the “shima-batake.” The present writer, however, cannot agree with this opinion in view of the fact that “shima-batake” are distributed even in diluvial tablelands that are entirely free from any danger of flooding, as well as for other reasons. The present writer holds the following view: In regions where “shima-batake” are distributed, the slope of the land surface is extremely gentle, and the surface abounds in micro-relief. (In general, the difference in height between the high parts and the low parts is less than about 80cm.) Again, the water-level of the irrigation canals in such regions is approximately the same as the height of the lowest part. Moreover, the source of irrigation water is far from abundant. In such a region, in the days before pumps could be used, the farmers had no choice but to level down the high parts and make paddy-fields in order to expand their paddy-fields. The present writer thinks that it was as a result of the expansion of paddy-fields in these regions by individual farmers that the complex distribution pattern of paddy-fields and upland fields was formed. Recently, in regions where plentiful irrigation water has been made available by the use of pumps, “shima-batake” have been leveled out, and the whole region has been made into paddy-fields. Again, in regions where the area of paddy-fields cannot be expanded because of the limitation of irrigation water, and in other places where it was felt desirable that the upland fields should be left as they were, numerous small “shima-batake” have been combined to form upland fields with large areas.

A study of Paridae community in Japan

1. Censuses of Japanese tits were made intensively at Tenryu River basin ca. 500m of altitude (102 times, 1957-'60) and Keito Mt. region below 1000m (95 times, 1963-'65), in Nagano Prefecture, Central Honshu. Supplemental censuses were made at: lowland Hokkaido (Sarobetsu, Kawayu, Gojukkoku and Onuma), subalpine Central Honshu (Kamikochi, Shiga), Shikoku (Kurokawa), Kyushu (Mt. Hiko, Ishiwara) and Tsushima (four places). These places had different vegetational environment and species composition of tits, but they were absent in pure evergreen broadleaved woods of southern Japan.2. The species of tits studied are: Aegithalos caudatus (Aegithalinae), Parus major, P. ater, P. varies, P. montanus and P. palustris (Parinae).3. At peripheral parts (Tenryu, Kurokawa, Ishiwara) of Paridae habitat of simple woods around human habitation, P. major and Ae. caudatus were main species; and only the former was found at the extreme periphery. P. varius joined them if there was a good amount of broad-leaved desiduous woods; P. ater occurred as a main member only during winter in Central Honshu where there was a mixed forest (Keito region); the main members were replaced in summer by P. ater and P. montanus at wet subalpine mixed forest (Kamikochi, Shiga); while in swampy lowland broadleaved forests of Hokkaido (Kawayu, Onuma, Gojukkoku), Ae. caudatus, P. major and P. palustris formed the main members, the last species becoming dominant in the more swampy part. P. varius and P. montanus occurred always in small numbers, but they may be more plentiful (dominate the others) elsewhere where they are best adapted respectively.4. The following three types of sympatry and ecological segregation among tits could be concluded:a. Two main species may coexist in similar abundance, but their types of social population fluctuation is different: Ae. caudatus concentrates into a compound family flock after breeding, while in P. major families are become dispersed. Thus, the two abundant species can coexist at peripheral areas.b. Two species may coexist in similar numbers and show parallel seasonal fluctuations, but the degree of fluctuation is different: Fluctuations of P. major and P. ater at Keito area were parallel but the wintering population of the latter species greatly increased, becoming very scarce in breeding season.c. One of the coexisting two species may dominate the other in number: P. montanus and P. varius in studied areas were decidedly few in number, although they coexisted with P. major and fluctuated parallel with it.5. Ae. caudatus is different from Parus species in the type of social population fluctuation and thus can be sympatric at such a peripheral part where P. major is abundant. Other Parus species may be similar in social fluctuation type, but coexist with each other by their different degrees of abundance in species composition due to different habitat preference or particular seasonal movement. P. montanus and P. varius, for example, are entirely allopatric in habitat, while P. ater is partly and seasonally sympatric with P. major and others.

Aerial Photographic Interpretation of Soft Ground (Part 1)

(II) A trial of interpretation of soft ground by the morphometric analysis of micro-geomorphology.1) A study based on the methods and techniques of “micro-landform” analysis on aerial photographs mentioned previously is carried out in case of the alluvial lowlands in the lower Tenryu River Region, close to Hamamatsu City, on the Pacific coast of Central Japan, before the discussin on the morphometric analysis of micro-geomorphology. From this study, the methods of the systematic classification of “micro-landform units” are proved to be useful to infer but surface materials also the surface layer type of soft ground.2) However the surface distribution ranges and types of soft ground are ascertained, the depth or thickness of the soft ground is not determined. As mentioned by Belcher (1960), it is difficult to interpret the thickness or depth of materials from aerial photographs. In order to examine the possibility of interpretation of the thickness of soft muddy layers which compose soft ground from aerial photographs, it is necessary to study the relationship between the thickness of the layers and the micro-geomorphological features seen on the photographs. For this purpose the writer tried to measure the distribution pattern of the “micro-landform units” by a simple morphometric analysis using aerial photographs. The morphometric data are compared with the geologic data obtained from bore hole excavations, in case of the alluvial lowlands formed by the Tenryu and the Ota Rivers.The distribution pattern of the “micro-landform units” is measured by “Micro-Relief Ratio (MR) ” defined byMR=Total area of micro-relief in a unit area/Unit area (1 sq. km.) ×100 (%) .Where, micro-relief means areas of shight elevation such as former channel bars, natural levees, etc., as well as abandoned low water channels.The value of MR shows the distribution density of coarse granular materials on the surface of alluvial lowlands, and the relative area formed by muddy deposits. From Fig 2-2., the total value of MR in a lowland area is thought to be a approximate index showing the geomorphic development processes, the stability of the depositional environment and the ratio of the volume of fine grained materials to the total volume of materials transported by the rivers in the recent years. Consequently, one can expect that the smaller velues of MR indicate thicker fine grained deposits.Based on these hypotheses, the relationship between MR and the thickness of muddy deposits including peat layers (UM & LM) is analyzed and discussed. Furthermore, the relationship between the “Damage Percentage (DP) ” of wooden houses caused by To-Nankai Earthquake in 1944 and MR is discussed.3) The correlation between the thickness of muddy deposits (Tm) and the value of MR is not so distinct as shown in Fig. 2-11 a & b. But, generally speaking, Tm increases exponentially with decreasing MR. The maximum thickness of UM appears at the value of MR between 8% and 32%, and the total thickness of UM and LM exceeds more than 30m. or 40m. at the value of MR of less than 20%. When the mean value of MR was calculated in the 1km. zone crossing the lowlands (MR mean), it is the area where MRmean is less than 20% or 30% that one can expect the coexistence of both surface layer type (UM) and deep layer type (LM) of soft ground. And in such areas, for instance natural levee zone and lagoonal delta of the Ota River, one can also expect that the total thickness of soft muddy deposits is greater than 30m. or 40m (see Fig. 2-10) .

PROBLEMS ON THE STREAM-PIRACY BETWEEN THE TENRYU AND THE TOYO RIVERS IN CENTRAL JAPAN

It has long been believed by many geographers in Japan that the Tenryu River beheaded the Toyo River along its middle course near Nakappe town, and then the Ochise River, a tributary of the former, encroached through the wind gap into a fossil valley of the previous main stream of the latter, having remained a valley watershed (Talw asserscheide in German) at Ikeba village. This valley watersched has a length of about 500 meters, sloping gently to eastward. Its west end is terminated by the valley-head of the Shimano-kawa, one of the source streams of the present Toyo River ; and the eastern margin slopes gently into the stream of Tero-sawa, one of the source streams of the Ochise River in the Tenryu drainage basin, forming several alluvial cones. Through his observations, the writer cannot approve of the opinion of stream-piracy above mentioned. The reasons are as follows:—1) The breadth of the Ikeba valley watershed is too narrow to assume that it was the previous main stream of the Toyo River.2) Both sides of the valley watershed show concave slopes with no terrace landforms.3) The outcrops along the valley floor are all composed of angular and ill-sorted talus deposits without water worn gravels. So the Ikeba valley watershed cannot be assumed to be the fossil valley of the Toyo River. On one hand, some geologists presumed a fault-line along this valley watershed, the pioneer of whom was B. Naumann, who found the “Medianlinie”, the main geotectonic line in southwestern Japan. Though the writer could not find any actual evidence of a fault, it is rather probable that the valley watershed here was originally formed as a fault valley.

Ikehata-mae Site in Shizuoka Prefecture

1) Situated at 255-9, Of uji 12-ku, Iwata-shi, Shizuoka Prefecture, this site lies on the west side of the higher part of Iwata-bara Upland rising on the east side of the Tenryu River. (Fig. 1, Mark×)2) Excavation was carried out for a week from August 21st to 26th, 1960, under auspicious of the Board of Education for Iwata City.3) The excavation began from Trench A measuring 20 meters by 2 meters, followed by the work on Trenches B and C lying on the north and south sides of the Trench A, respectively. Layers in the site are as follows. (Fig. 2)I Humus (black soil).........20-30cm II Dark brown soil.........30-40cm III Brown soil.........10-40cm IV Light yellowish brown soil.........30-40cm V Yellow clay with gravel.........30-40cm VI Gravel.........?The second dark brown soil is the only layer yielding artifacts, which were always found together with gravel. Judging from such a status, they had something associated with gravel. The association is common to all the trenches in this site. In addition, nothing but stone implements was excavated from the site.4) The materials of the stone implements are sandstone, slate and shale, largesized ones being made of the first two materials, while small ones of the last, with a single exception made of chert. Accordingly, the industry carried in this site can be said to have developed according to the so-called Bladetechnique using the shale as its main material. (Figs. 3-6)5) Artifacts from the site are as follows : Knife-blade.........39 Bifaced tool (or point?).........1 Spatulate scraper.........1 Gravers (burins).........5 Burin-spalls.........4 Scrapers......... Blade cores.........7 Blades.........48 Grooved hone.........1 Hones.........5 Hammer stone.........1 Polishing and rubbing stones........5 Milling stone.........1 Flakes and chips.........202 Total: 3236) This site is characterized by the Stone-age Culture rich in variety of stone implements represented by the so-called knife-blade stone implements. In other words, it can be said to be of the Knife-blade industry which has a strong tendency to the microlithic. Among finds are included a milling stone, the kind of which has never been discovered before out of sites of the same age, polishing and rubbing stones, hones, etc. According to the fact, economical basis of the Japanese Pre-ceramic Culture Age, which has been thought vaguely to be on the life of food gathering mainly by hunting, now comes to the stage to he reconsidered with materials newly unearthed from this site.

Development of Irrigation System and Land Use on the Tenryu Alluvial Plain and the Mikatahara Tableland

The present Paper has two main objectives---the first is to make an inquiry into the problem of the reasons why, unlike in the case of most alluvial plains in Japan, the ratio of paddy fields to cultivated land is small in the Tenryu alluvial plain, and also to study the type of land use which is prevalent there; the second is to make an investigation of the progress made since the Meiji Restoration in the retarded development of the Mikatahara Tableland, which is an elevated fan lying to the west of this alluvial plain.In the first place, the present writer has tried to clarify the distribution pattern of the paddy fields and upland fields in the alluvial plain, and he has taken special note of the wide distribution of the peculiar butte-like upland fields. The upstream region of this alluvial plain constitutes a fan, while the downstream region forms a delta. As there is a complex distribution of former river courses, natural levees, flood plain swales, flood plain bars, etc., in the delta region, the land surface abounds in microrelief. The irrigation water for the paddy fields in this alluvial plain is supplied by the irrigation canals leading from the mouth of the gorge of the Tenryu River. However, because of the low water-level of the Tenryu River, the water-level of the irrigation canal is likewise low; in addition to this, the slope of the plain surface is extremely gradual, so that in the days when pumps were unknown, it was impossible to supply water to parts of the plain that were even only slightly elevated. Thus, the present pattern of land use which resulted from these circumstances dates back to old time. In order to obtain an income from upland field crops, the cultivating farmers cultivated sweet potatoes, wheat, and barley, to which were added cotton, indigo-plant, mulberry, sponge-gourd, peanuts, melons, and other commercial crops which were raised in accordance with the vicissitudes of the times.The Mikatahara Tableland is located at an elevation. Hence, it was difficult to procure water from the Tenryu River. Moreover, as the ground water is deep, drinking water was not easily obtainable, the result being that almost the whole of the tableland remained unreclaimed even until as late as the Edo Period (1603-1867). This unreclaimed land was utilized by the cultivating farmers dwelling in the lower regions as source for the grass used in the production of compost. In the Meiji Period (1868-1912), portions of this land were developed by members of the warrior class who had become cultivating farmers, but for the most part, the land became a crown holding. In the latter half of the period of crown holding, approximately half of the land was reclaimed by cultivating farmers of the neighborhood to whom it was loaned. In time, the extensive areas left uncultivated became military grounds. After the Second World War, most of the military grounds were released for development as upland field land. Later, however, plans were altered, and ultimately, as part of the project for the multiple development of the Tenryu River, modern develoment plans were made for the making of paddy fields by supplying water by means of a large irrigation canal from the large-scale dam constructed in the Tenryu River. Work on this project is currently under way.

Aerial Photographic Interpretation of Soft Ground (Part 1)

(II) A trial of interpretation of soft ground by the morphometric analysis of micro-geomorphology.1) A study based on the methods and techniques of “micro-landform” analysis on aerial photographs mentioned previously is carried out in case of the alluvial lowlands in the lower Tenryu River Region, close to Hamamatsu City, on the Pacific coast of Central Japan, before the discussin on the morphometric analysis of micro-geomorphology. From this study, the methods of the systematic classification of “micro-landform units” are proved to be useful to infer but surface materials also the surface layer type of soft ground.2) However the surface distribution ranges and types of soft ground are ascertained, the depth or thickness of the soft ground is not determined. As mentioned by Belcher (1960), it is difficult to interpret the thickness or depth of materials from aerial photographs. In order to examine the possibility of interpretation of the thickness of soft muddy layers which compose soft ground from aerial photographs, it is necessary to study the relationship between the thickness of the layers and the micro-geomorphological features seen on the photographs. For this purpose the writer tried to measure the distribution pattern of the “micro-landform units” by a simple morphometric analysis using aerial photographs. The morphometric data are compared with the geologic data obtained from bore hole excavations, in case of the alluvial lowlands formed by the Tenryu and the Ota Rivers.The distribution pattern of the “micro-landform units” is measured by “Micro-Relief Ratio (MR) ” defined byMR=Total area of micro-relief in a unit area/Unit area (1 sq. km.) ×100 (%) .Where, micro-relief means areas of shight elevation such as former channel bars, natural levees, etc., as well as abandoned low water channels.The value of MR shows the distribution density of coarse granular materials on the surface of alluvial lowlands, and the relative area formed by muddy deposits. From Fig 2-2., the total value of MR in a lowland area is thought to be a approximate index showing the geomorphic development processes, the stability of the depositional environment and the ratio of the volume of fine grained materials to the total volume of materials transported by the rivers in the recent years. Consequently, one can expect that the smaller velues of MR indicate thicker fine grained deposits.Based on these hypotheses, the relationship between MR and the thickness of muddy deposits including peat layers (UM & LM) is analyzed and discussed. Furthermore, the relationship between the “Damage Percentage (DP) ” of wooden houses caused by To-Nankai Earthquake in 1944 and MR is discussed.3) The correlation between the thickness of muddy deposits (Tm) and the value of MR is not so distinct as shown in Fig. 2-11 a & b. But, generally speaking, Tm increases exponentially with decreasing MR. The maximum thickness of UM appears at the value of MR between 8% and 32%, and the total thickness of UM and LM exceeds more than 30m. or 40m. at the value of MR of less than 20%. When the mean value of MR was calculated in the 1km. zone crossing the lowlands (MR mean), it is the area where MRmean is less than 20% or 30% that one can expect the coexistence of both surface layer type (UM) and deep layer type (LM) of soft ground. And in such areas, for instance natural levee zone and lagoonal delta of the Ota River, one can also expect that the total thickness of soft muddy deposits is greater than 30m. or 40m (see Fig. 2-10) .

Running Sands of Tenryu River and its Problem

Running Sands of Tenryu River and its Problem

FLOOD DEPOSITS OF THE TENRYU RIVER IN THE VICINITY OF KAWAJI, NAGANO PREFECTURE

On June 28, 1961, a disastrous flood took place at various parts of the Tenryu River course caused by heavy rainfall accompanied by the Baiu front. In the district of Kawaji, that is situated at the southern end of ma Basin occupying the upper part of the Tenryu River drainage, a violent inundation occurred and the deposits brought by the flood water covered the inundation area thickly. Except those of branches, the flood deposits are divided into three categories, that is, gravelly, sandy and silty materials. In the cases of the sandy and silty materials, it is recognized that the deposits are well sorted. Namely, grain size distribution of most samples from these two is limited between the two sizes as is shown in . Fig. 4. Then, the writer determined graphically the finer limit of the sizes of a sample and presumed that the particles of sediments smaller than this size moved in the form of suspended load and flowed out with flowing water. If we represent the value of this critical size by “d0”, and the value of settling velocity of do in standing water by “w0”, w0 may be proportional to values of the vertical component of the turbulent flow which are functions of the velocity of the main flow. The distribution of w0 is shown in Fig. 5. Considering the foregoing aspects and Fig. 5, it may be interpreted that the flood-flows reduced abruptly its velocity near the entrance of the studied reach, and its high velocity zone forms a meander in the middle part of the flooded area while the flood deposits were being settled.

Studies on the fluctuation of number of Long-tailed Tits along the slopes of the River Tenryu, Nagano (2)

1. This paper discusses the seasonal fluctuations of the number and flocking of Aegithalos caudatus trivirgatus along slopes of the River Tenryu, Nagano. It is based on 166 observations made during 1956-60, and, following the first paper (Tori, No. 75, 1960), reports the behaviour of flocks in different divisions of the home range.2. The study area consisted of 9 divisions, A to H. The 90% of the total number observed occurred in H, 40% in E and F, 20% in A and B, the divisions being closer to human habitation towards A.3. In division H, flocks were continuously seen with the peak numbers in May and June, while in A and B they occurred from autumn to the next spring, but disappeared during the summer.4. The flocks tended to move from H to A divisions in their daily, as well as annual behaviours, in the latter the movement having been commenced from September and October.5. The 30% of the total number observed lived between the divisions A and H, and only 8% of which adhered to A-division-side and the lest towards H.6. Only 2% of the total number observed remained in the study area for breeding and this may be due to the budding off of small flocks which was noticed several times from autumn to winter.7. The budding off of small joint flocks towards winter is directed from H to A-divisions. There were also a few movements among them and the last flocks which immigrated into A-H area settled as breeders.8. In April and May a large joint flock was formed by gradual concentration of family flocks.9. Pair formation tended to be earlier towards A-division and was delayed towards H, where the breeding was prolonged.

Studies on the fluctuation of numbers of Long-tailed Tits along slopes of the River Tenryu, Nagano

1. This study on the Long-tailed Tit was made during February 1956 and August 1959, at the slopes along the River Tenryu, Kamigo-mura, Shimoina-gun, agano.2. Seasonal fluctuation in the number of individuals and flocking behaviour are described.3. Seasonally, the number of individuals was maximum in mid. and late June and minimum in late March.4. Sudden big change of number was characteristic, showing the movement by flock unit.5. In two years of the study, 30% of the yearly maximum remained to breed within the study area. The breeding success was ca. 70%, and rates of increase after breeding was about 140% and 180%.6. The types of fluctuation of the number of individuals were: 1) January-March With lowest number but least variable. 2) April-May Number suddenly increased by occurrence of family flocks. 3) June-July With maximum nember of individuals. 4) August-December Number less than maximum but with frequent fluctuation between 10-30 birds.7. Seasonal flock classification was possible as follows: 1) February-April Period of pair formation. 2) May Period of 'family flocks'. 3) June-July Period of a 'large joint flock'. 4) August-October Period of breaking up into 'medium, and small joint flocks'. 5) November-January Period of 'winter flocks' and formation of home range.8. The flocks of the study area had communication with those of adjoining areas, especially in the period of 'large joint flock' of the summer.9. One to two winter flocks of the total of 20 individuals inhabited a belt of area about 120 km2. But, occasional imigration of the flocks of other areas and the emigration of some early wandering flocks were noticed.

Problems of the Quaternary History of the Atsumi Peninsula and its Adjacency in the Tôkai Region

The Quaternary sediments in the Atsumi district can be divided into four stages, each reflecting a submergence, same as other areas in the Tokai region.The earliest stage is the Atsumi formation which is considered to be a deltaic deposit of the ancient River Tenryu. Its molluscan fauna indicates a large shallow bay such as present Ise Bay, and neither a small inlet nor an open sea. The fauna is quite different from the present community of the south open coast of the peninsula. It might be surmized either the Shima Peninsula was further projected to the east at that time or the like of a peninsula existed at that time to the south of the present Atsumi Peninsula, preventing the ancient large bay from free communication with the south open sea.An up-warping movement has been taking place on the Atsumi Peninsula since the early Pleistocene. The brachy-anticline thus produced agrees with the present topography of the peninsula, and reveals close resemblance to those of Udo hill and Makinohara area in the Tokai region.

天竜川中流域山村の地域性に関する若干の考察

The object areas of consideration by the author are:a) the catchment-area of the Toyama-gawa, one of the tributaries of the River Tenryu (on the side of the Akaishi Mountains).b) the catchment-area of the Wachino-gawa (on the side of the Kiso Mountains).It may be admitted to say that the present state of a mountain village can not be correctly recognized without considering over the process of its social development.The author has comparatively considered several mountain villages in the two areas descripted above and emphasis were put on the differences between these two groups of villages in order to get true pictures of their present status.In some respects, they have common characteristics; for example, both areas supply themselves for food supporting them only for three months in a year. In other respects, however, remarkable differences are observed between these two, especially their economic conditions. Forestry offers a good example; at present, the former shows vigorous activity in lumbering, while the latter doesn't, because of shortage of its forest resources.1) The causes which have brought the differences in the present activity in lumbering are as follows: -the catchment-area of the Toyama-gawa has much larger wooded land than that of the Wachino-gawa, since the former has been left behind by the latter in the progress of carrying capacity. The roads in the latter districts were repaired as early as the first 10 years of this century, while in the former it was in 1944 that the roads for auto-trucks were built for the first time, and as a result, the private-owned forest resources, the main spring of todays activity, has long been preserved without being deforested.2) From feudal days, there runs the Sanshu highway connectitg the Central Highland with the Tokai district through the upper region of the catchment-area of the Wachino-gawa.Owing to this environment, the life relying upon this highway was established. Its origin can be traced back so far. But when the people were left behind the modernization of traffic, they were forced to depend more and more upon the forest resources in order to support their life. Unfortunately by such regrettable denudation during World War II, their economic condition ran on a dead rock.In order to overcome this difficult situation, the following may be suggested to be effective;i) surface rights of the forests separately belonging to each village, though once divided, should be united again, and all the forests should regain their original status as a complete common property.ii) after its accomplishment, rationalization of the forest management should be carried out.3) As for the area of the Toyama-gawa, rationarization of the managment both for the private forests and those belonging to the communities would never fail to bring much benefit to the majority of the inhabitants in future.4) It is necessary for each area to divide its private-owned forests into two parts, namely, into forest for economic use and for agricultural use; the forest for economic use should be divided again into two parts, one is for lumbering, the other for charcoal. It is needless to say that in each of these three parts thus divided, long year range plans for tne purpose of accumulating forest resources should be put into practice.Regarding the area of the Wachino-gawa, the author feels it proper to say that, for the reconstruction of its economic life, rational management of the forests for charcoal production ought to be strengthened.