The intensity of landform transformation due to various kinds of large-scale land development in Japan has been magnified since the 1960's when Japanese postwar high economic growth came in real earnest. Japanese geographers, however, paid only a little attention to such phenomena except natural disasters caused through human impact on land. On the other hand, geographers in foreign countries, such as the United Kingdom, the United States, France, Germany and East European countries, have continuously recognized from early times the important role of man as a geomorphic agent and they have accumulated field studies on landform transformation in the process of systematic establishment of anthropogenic or environmental geomorphology.
In the last few years, the importance of landform transformation studies has gradually been recognized in Japan. In order to promote systematic and comprehensive studies, a Working Group on the Man-Made Landforms and Land Transformation was organized in 1980 in the Association of Japanese Geographers, and a symposium on “Land Transformation and Related Environmental Changes” was held in 1981. This special issue on “Landform Transformation” carries the papers which are rewritten from the reports presented in the symposium.
This paper aims at overviewing the trends and problems inherent in the previous and recent Japanese studies on anthropogenic transformation of landforms and landforming process through a comparative review of foreign studies and at promoting the progress in this field. In the English-speaking countries, landform transformation problems have been studied since Marsh (1864) and Sherlock (1922), who wrote “Man and nature” and “Man as a geological agent”, respectively. Among the problems, man-induced soil erosion has been recently highlighted over again to contribute to solve the environmental problems, which proved to be more urgent in the 1970's. In the French-speaking countries, accelerated landforming processes caused by human activities have been studied both in the homelands and the former overseas settlements through a climatic geomorphological approach. In Germany, the concept of anthropogenic geomorphology was introduced by Fels (1934) and the studies similar to those in the French-speaking countries have been performed mainly in Central Europe. In the East European countries, in particular in Czechoslovakia and Poland, classification and mapping systems of anthropogenic landforms have been intensively studied.
Japanese geographers tried to analyse both ancient and recent landform transformation and related environmental changes as a part of the subjects of historical and applied geography, respectively, though they paid little attention to the man-made landforming processes themselves which have been recognized through recent activities by the members of the Working Group on the Man-Made Landforms and Land Transformation.
However, many tasks require further research in the context of landform transformation studies and their application to environmental management. In particular, following subjects must be stressed hereafter.
1. Socio-economic analysis related with landform transformation and its control,
2. Morphogenetic classification and mapping system of man-made landforms,
3. Historical approach enabling the reconstruction of long-term man-induced geomorphic processes,
4. Comparative geographic studies including climatic geomorphological approach,
5. Experimental studies and field measurements of man-induced geomorphic processes,
6. Assessment of the magnitude, areal extent and temporal sequence of the resulting effects on environment, and
7. Comprehensive land transformation studies and their application to environmental managemeut.

View full abstract

Large-scale landform transformations for various purposes of land developments have been recently active in Japan. They have required the researchs from the viewpoint of anthro-ogenic geomorphology which contains both man-made and man-induced landforms and p related phenomena in its scope. This paper reveals the recent trends of the change in types of landform utilized and estimates the magnitude of man-made landforming processes in the intensely developed lands in Japan.
Because the statistics showing the actual states of landform transformation have not been sufficiently prepared yet, the estimation of magunitude of artificial landforming processes in this study progresses inevitably in a felicitous combination of selected detailed surveys and effective generalization. First, landform modification types and magnitude are investi-gated with the aid of very large-scale scheme drawings etc. at the small number of typical development sites for each purpose and in each type of landform. The area of develop-ment and the volume of artificially-removed earth provide the simple indices of landform-modification magnitude. The greater volume between artificially cut material and filling one is used to represent the volume of artificiallyremoved earth in the site because most of earth cut from higher location is usually applied for filling in the lower location within the same development site except for ones in the flat lowlands and the reclaimed lands. The normal depth of surface disturbance is defined as the average of the ratio of the above volume to area of the site for both every development purpose, e. g. residential, industrial, agricultural, etc., and every geomorphic location which is classified into the follwing four intermediate-scale geomorphic units: the lowlands (Holocene alluvial and coastal plains), the terraces (mostly of late-Pleistocene age), the hills (mostly composed of early-Pleistocene and/or Neogene de-posits with mid-Pleistocene cover in part) and the mountains. The areas for several pur-poses of development sites, which are usually provided with administrative districts, are also retotalized according to these geomorphic units. The normal depth of surface disturbace and the total area of development, both of which are arranged according to the development purposes and the intermediate-scale geomor phic units, are applied for the estimation of the total volume of artificially-removed earth.
Some results of the estimation are as follows:
1. The land development for various purposes became very active around 1960 and has been advanced with distinct decrease in the mid-1970's. The trends correspond well with changes in the national-scale socio-economic activity.
2. The rapid increase of intense land-developments since 1960 has proceeded in concurrent with the remarkable changes in locational condition of landform for residential, agricultural, and industrial sites from the lowlands and terraces to the hills, and further to the mountains in the case of agricultural development. For instance, more than 40% (in area) of the newly-developed residential sites are located in the hills. Moreover very extensive area of golf courses, which may exceed the total area of residential development, has been developed during the same period and most of them are located in the hills.
3. The increase of development area and the changes in its locational condition of landform to the hills have caused distinct rise of artificially-removed earth volume. The total volume of earth removed artificially during 20 years since 1960 in Japan may reach the order of 10¹⁰m³, which means 1 or 2×10³m³ of earth material has been removed an-nually from every1km² area.

View full abstract

In spite of rapid expansion of man-made landforms after the 1960's in Japan, Japanese geographers, especially geomorphologists have paid little attention to this problem.
As geomorphologists perform genetic approach to natural landforms by means of precise analysis of geomorphic processes, man-made landforms must be studied genetically by precise analysis of the processes of human actions. Present author offers the genetic approach to the man-made landforms by analyzing 1) the original geological and geomorphological conditions, 2) the purpose of human actions, 3) the method of transformation, 4) the characters of businesses acting on landforms, and 5) the regulations controlling landform transformation.
From such a viewpoint of analysis, the author deals with the man-made landforms resulting from the opencast mining of porcelain clays and silica sands around Seto City, Aichi Prefecture. The studied areas are located in the northern part of Seto City and the Yakusa district of Toyota City, where many mines are densely concentrated because of thick deposits of high quality porcelain clays and silica sands. These areas are composed of gravel beds of the Yadagawa Formation, Plio-Pleistocene (the Mizuno Gravel Bed) where low relief hills with summit level of 180_??_190 m high spread over (Fig. 1). The Seto Forma-tion beneath the Mizuno Gravel Bed is composed of porcelain clays and silica sands which are just mined, and are subdivided into three members ; the Motoyama Kibushi Clay Bed (upper), the Mizuno Clay Bed (middle), and the Yadoko Silica Sand Bed (lower) (Figs. 2 and 3).
Landforms of mining fields are generally characterized by disordered distribution of large mining hollows such as honeycombs. Each hollow consists of steep cliffs, step-like benches, . abandoned roads and settling basins in the bottom of hollows. Such features are common to almost all mining fields (Fig. 4, alos see stereo-pair air photographs). The Mizuno Gravel Bed which is called the “surface layer” by mine workers is evacuated and transported to the abandoned mining fields or the upper part of valleys to make flat or rolling surfaces. The dump of the evacuated surface layer, called “thane-yama”, is used to fill up: the abandoned mining hollows.
The ceramic ware industry of the Seto district is one of the traditional localized industry of Japan which dates back to the 11th century. In general, scale of business is very small and the working system is old-fashioned. Such character also reflects on the mining works. About eighty percent of mining businesses have less than ten workers (Table 1), and the area of each mining field is also very limited (Figs. 5 and 6). This results in numerous disordered congregation of honeycombed mining hollows.
Since the mining of porcelain clays and silica sands was provided under the Law of Mining Safety enacted in 1951, the mining method was gradually changed from pit mining to opencast mining for the sake of safety of workers by the administrative instruction of the Local Mining Safety Office of Nagoya. After the World War II, bulldozers were intro-duced as digging and excavating machine and motor trucks for transportation of mined minerals spread over this area, leading to the considerable increase of mining efficiency (Table 2). Moreover, especially after the 1960's, the rapid propagation of digging machines such as large bulldozers, power-shovels, loader shovels have greatly exaggerated the land form transformation. Present detailed features such as height and width of bench cliffs, benchs and roads of mining fields seem to be provided by the capacity and function of these heavy machines and dump cars.
Mining regulation is a most important factor controlling the landform transformation. The Local Mining Safety Office of Nagoya guides mining businesses according to the guidline for the opencast mining of non-metal ores (Table 3) under the Law of Mining Safety.

View full abstract

This paper describes the large-scale post-World War II urban development and the counter-measures planned for environmental protection and disaster prevention in the municipality of Kobe. The following is the summary.
1. The urban development has progressed with rapidity since the 1960's.
2. The large-scale development was initially concentrated in piedmont areas near the central section of the city but has been gradually expanded to remote mountaineous areas, mountain tops and hill areas.
3. The acreage of development per development program was approximately 20 ha in the beginning but has been gradually enlarged to above 50 to 60 ha.
4. Public undertaking predominates in the development.
5. This large-scale development was purposed to obtain rock and soil required for the reclamation of land along the coastal area, because of the solution of deficiency of flat land areas in Kobe City and also of the prevention of mountain slope slide disaster.
6. The reclaimed land was intended for enlargement of port facilities, public utility, industrial and residential areas.
7. Various countermeasures for environmental protection and disaster prevention have been studied in planning the civil engineering works for this large-scale development program The details are itemized as follows:
1) the suitability of a place getting of rock and soil used for the waterfront reclamation and the conservation of landscape
2) methods of cutting mountains
3) transportation methods of rock and soil
4) prevention of sediment transport due to heavy rainfalls during and after cutting works
5) flood control systems
6) slope stability
7) prevention of changes in the wind system
8) assessment of changes of ground-water flows by reclamation works
9) the others

View full abstract

Most landforms which we see now do not reflect excludingly the results of natural forces. They were formed in various times of the past by pure natural processes, by natural processes affected by man and/or throughly by human activities, and they were later in some measure modified.
In the Sekkasen region in Osaka Prefecture mentioned here, landform transformations were remarkable from the 5th to the 12th century. They are summarized as follows;
Many of the small old tombs are located on the tops of hills, on the ridges of lower hills and upper terraces. On the contrary, most of the big old tombs, the biggest of which amounts to 10⁶m³ in volume, were constructed on middle and lower terraces. The direct transformations by the construction of old tombs were excavation and accumulation of soils, and the secondary transformations were coused by soil erosion, increase of the width of rivers and of the volume of sediments, changes of river courses and so on.
Next, ruins of the kiln of the “Sue-ki” were extensively distributed on the hills and the terraces. In case of the Senpoku Hills, 70% of the ruins of the kilns are concentrated on the slopes of hills and the cliffs of terraces. By construction of these kilns, not only landforms but also vegetation were remarkably modified. As the concentrating area of the ruins of the kiln coincides with the area of the Senpoku New Town, about 80% of these ruins were destroyed and disappeared by the construction of roads and housing lots.
The aim of the construction of huge reservoirs and ditches in this region was to irrigate the terraces. While the reservoirs were built in the lower to upper reaches of the rivers, the ditches were dug to conduct water of the east rivers to the terraces of the west. At the middle of the 5th century, the middle terrace, where the relative height from the flood plain was the smallest, was chosen to construct a reservoir, and at first the “Yosami-ike” Reservoir was constructed. Its aim was to reserve temporarily the water of the former Amano River and dissected valleys which cut into the terraces, and to send water to the lower reaches of the river afterwards.
The “Hario-no-taiko” Ditch was constructed at the middle of the 6th century mainly to conduct water of the former Tsuzuyama River into the middle terrace of the west. The excavated length on the terrace amounted to 2, 000m, and the irrigable area was about 550 ha. Further, the “Komuku-no-taiko” Ditch was constructed about the end of the 6th century for the same purpose. Total length of the ditches was about 6, 000m, and the irrigable area on the terrace was about 300 ha.
The “Sayama-ike” Reservoir was constructed by damming up the whole valley plain formed by the former Amano River at the beginning of the 7th century when exploiting of terraces of the lower reaches was in advance and the need to irrigate the upper reaches of the river became pressing. It is considered that at the beginning of the construction the length of the north bank was about 300m and the area of the reservoir was about 20 ha. It was, however, enlarged to more than 50 ha in 1608. It took today's shape by the reconstruction of it in the 1920's. In addition to this, with construction of the reservoir, the “Yoge” Ditch was dug as a draining ditch extending over 1, 000m in total.
By introduction of the “Jon” grid-system, an ancient land division system, not only the lands with micro-reliefs were levelled, but also old dissected valleys, irrigation and draining ditches, footpaths separating rice fields and so on were arranged in order.

View full abstract