The rice reduction policy in Japan has been enforced since 1970 for the purpose of solving the problem of overproduction. This has largely influenced the paddy field land use throughout the country. Farmers' response to this policy varies by region. In this paper, the purpose of study is to consider both the factors making the variation among farmers' responses to this policy and the characteristics of one-crop farmers who have been influenced by the rice reduction policy. The areas of study are Miho and Azuma villages in Ibaraki Prefecture. The former is located in southern shore of Lake Kasumigaura and the latter in the lower plain of Tone river. These are typical one-crop areas, i. e., rice, in Kanto plain.
Farmers have individually changed their crops in the Miho village. On the contrary, in the Azuma village, the crop changing is carried out by village community. The difference of these responses to the rice reduction policy largely depends upon the one of physical soil conditions and social conditions as follows:
In the Miho village, soil of paddy field is drained or ill-drained. A lot of part-time farmers live in this region and they have farm fields under 1.5 ha. The main source of their income is not the farming income but full time salary in other industry. The influence of the rice reduction policy on household incomes is not so much as that of other one-crop paddy field regions. Consequently, individual farm household can allot other crops to their own drained paddy field at will. Moreover, these farmers get the same profit per 10 ares as that of rice growing by adopting both soybean growing which has a benefit of the crop changing subsidy, and wheat growing as a second crop.
On the other hand, although most of the farmers are part-time employees in other industries in the Azuma village, their incomes mainly depend upon agricultural income and they can not expect so much other income. For this reason, they are much dependent on the paddy income. Most of the paddy field are consisted of ill-drained soil. Thus the farmer in this region took the passive attitude toward the early rice reduction policy. However, at the beginning of reinforcement of the rice reduction policy from 1978, a lot of farmers feared that the enforcement of this policy might diminish the farm house paddy income. In order to find a way out of these difficulties, it was proposed that the farmers should response to the rice reduction policy positively and change from one-crop farming to plural-crop farming to increase the income. For that reason, they carried out the land improvement and established the mutual cooperation system. Consequently, the crop changing area from paddy field exceeded double during the four years from 1978 to 1982. Mutual cooperation system means that the full-time farmers rent the crop changing area of paddy field from small part time farmers. As the result of the establishment of mutual cooperation system, the number of full-time farmers with plural-crop farming has increased. It clearly illustrates that mutual cooperation system played an important role in maintainnning and developing both full-time and part-time farming. However, the income of farmers with 2.0 ha farm has not increased after the establishment of the mutual cooperation system. Such problem will be an important subject for regional agriculture in the future.

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In the Daisetsuzan Mountains which are mainly composed of Quaternary andesitic lavas a number of block streams and block slopes are recognized. The block stream on the Chubetsudake NW slope is one of them. This study aims to elucidate the origin and the process of movement of this block stream on the basis of the data on the morphological and sedimentological characteristics of the block stream and the size and orientation measurements of boulders.
The block stream shows following characteristics.
1) Most of deposits have an openwork texture.
2) Ridges and furrows are formed on the surface of the block stream.
3) Transverse ridges and furrows are found on the upper part of the block stream and longitudinal ones are found on the lower part. But at the central winding part of the block stream ridges and furrows are transvers outside and longitudial inside.
4) The block stream is rarely covered with vegetation except lichen.
5) Brocken trees are found at the lower part of the block stream.
6) Two tephra layers are recognized on the boulder surface. The age of the upper layer is ca. 200 y. B. P. and that of the lower one is thought to be several hundreds years ago at most because the two tephra layers are only interbedded with a thin humus layer.
The results of the size and orientation measurements of boulders can be summarized as follows.
1) Boulders are better sorted on the several convex part in the longitudinal profile than remaining parts.
2) At the several localities in the longitudinal profile the orientation of boulders tends to parallel to the slope direction.
From the above, the origin of the block stream is thought to be a rockslide-avalanche. The directions of the ridges and furrows at the central winding part of the block stream suggest that the velocity of the movement was lower outside and higher inside.
The ages of the two tephra layers indicate that the block stream was probably formed around several hundreds years ago.
In the Daisetsuzan Mountains which contains young volcanoes there is a high possibility that a volcanic earthquake might trigger a rock avalanche. The last eruption of Asahidake is inferred to take place about 500 years ago. As this age approximates to the tephrochronologically inferred age of the block stream, the volcanic activity of Asahidake possibly caused the rockslide-avalanche on the Chubetsudake NW slope.

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The Nagdong River Basin occuping the area of 24, 000km² with 525km long trunk stream is located in the southeastern part of the Korean Peninsula. The alluvial plain along the lower Nagdong is divided into two areas, i. e. the down-reaches basin and the river-mouth delta.
This study intends to clarify geomorphic characteristics and geomorphic development of this plain in relation to post-glacial sea-level change. The investigation is made up of micro-landform classification, stratigraphic analysis, and restoration of depositional environment.
The main findings are as follows:
1) There are buried valleys below the 50-70m thick alluvium in th delta, and below the 15-10m thick one at Woegwan located about 210km upstream from the river mouth.
2) The alluvium of the delta is classified into the following six different layers in ascending order; Basal Gravel (BG), Lower Silt-Clay (LC), Middle Sand (MS), Middle Silt-Clay (MC), Upper Sand (US) and Upper Clay (UC). The LC and MC are considered to be the bottom-set bed deposited in the transgression phase. The MS and US are considered to be the foreset or topset bed formed in the regression phase.
3) The above mentioned sequence of alluvial deposits shows that there are two large sealevel fluctuations in the post-glacial time in this plain as demonstrated in the plains of Central Japan (Ikeda, 1964).
4) In the longitudinal profile, the LC and MC show a wedge-shape structure which is sharp upstream. These layers were traced up to 50km (LC) and 150km (MC) from the river mouth.
5) In the cross-section of down-reaches basin, silty clay lenses are recognized on the both sides of main stream and are identified as back marsh deposits which formed in submerged environment during the transgression.
6) Geomorphic development of this alluvial plain are summarized as follows:
a) The down-reaches of Nagdong River was drowned in the postglacial transgression. This drowned valley was consequently filled continuously with stream deposits supplied from the neighbouring mountain sides and with flood deposits provided from the main Nagdong River sides. The area of water surface was gradually decreased. The back marshes such as Upo, Samolpo etc., are the latest remnants of water surface.
b) The delta plain formed on the river mouth is made up of three different geomorphic units, that is, the main delta, the lower delta and the marginal marsh. In the bay, the main delta was formed by bifurication of main stream resulting in the formation of interdistributary islands. By contrast in the bay mouth which is affected by open sea, the lower delta consisting of beach ridge, swale, and barrier islands has been developed. The development of main delta provided the enclosure of water surface and resulted in the formation of marginal marsh.

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Many factors control morphological and structural features of alluvial fans. The author assessed quantitatively by statistical analyses the degree of importance of factors influencing the features of fans (Table 9 and Fig. 3).
The dominating factors that exert an influence upon volumes of alluvial fan deposits are in order of importance as follows; the stage when fans were formed, drainage basin area, vertical displacement during the Quaternary, a sedimentary environment, existence of an intermontane basin, and presence of volcanoes (Table 9). Because the stage is the most important factor influencing the volumes, it is demonstrated that the interpretation of the differences of volumes in each stage is very important. Furthermore, all the dominant factors, with the exception of sedimentary environment, control the debris production. Consequently, the volumes are determined strongly by conditions of debris production.
Concerning the alluvial fan area, the dominating factors are drainage basin area and stage (Table 9). The size of fans during specific stages are in good agreement with volumes of fan deposits (Table 8). These phenomena are attributed to great fluctuations of debris from one stage to another. Incidentally, under suitable conditions of other factors the areas are not necessarily large in spite of the great volumes of fan deposits. Rather the areas are very much related to the thickness of the fan deposits.
Mean slopes of alluvial fans are controlled primarily by relief ratio and drainage basin area, and secondly by geology (rock type) of drainage basin and climatic conditions. Alluvial fans are steep in drainage basins underlain by tuff, agglomerate, and volcanic rocks, whereas in Southwest Japan where the precipitation is intense they are gentle.
The factors controlling the depths of stream downcutting in alluvial fans are in order of significance as follows; the time elapsed after the cessation of fan formation, stage, variations in climatic conditions, existence of volcanoes, vertical displacement, These factors are concerned with climatic changes, crustal movement, and volcanic activity which produce changes of transportation load. Of the factors, it is demonstrated that the interpretation of the differences of downcutting for each stage is the highly important. On the contrary, such factors as drainage basin area, existence of an intermontane basin, relief ratio, and geology of drainage basin, which cause changes of transportation load to a lesser extent, have little influence upon the depth of downcutting.

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