1. Japan is a rainy country, not infrequently visited by heavy rainfalls. “Syûchugô-u” is rather a new word in Japanese with a special nuance which means rainfall characterized by its tremendous amount concentrated within a narrow limited area in a short interval of time.
Such a sort of rainfall is liable to cause a terrible damage for human living and activities, hence this subject becomes one of the most urgent problem in the field of applied meteorology and climatology in Japan.
In the previous studies (1967, 1968, 1970), the present author made clear the distribution and secular change of heavy rainfalls for the sixty years up to 1960. Before a full discussion in this paper, an exact definition of heavy rainfall is indispensable. In the first paper (1967), the writer adopted the occurrence number of heavy rainfalls whose daily amount exceeded 10% of the annual totals in the respective years. However, someone suggested him that this definition is too severe for the practical purposes and then it was altered to 5% of annual totals in the second paper. Notwithstanding, 5% is adequate in a case while in others 10% is more preferable according to circumstances and the . standard limit is by no means unique according to the purpose and aim of the study. For this reason, both are used in this paper as occasion demands and, for distinguishing them, those exceeding 5% of annual totals are called “heavy rainfall” and the others “extraordinarily rainfall”. At many places in Japan, the latter commonly occurred once in about twenty years while former was experienced once in about three to four years.
2. Heavy rainfall is most frequent in typhoon and Bai-u or the rainy season in early summer in Japan. For the determination of these two types, the following method is used. Taking the twenty years' record of monthly and daily rainfalls, number of heavy rainfalls that occurred in the earlier summer from May to July (A) and those from August to October (B) are reckoned. If (A) is significantly larger than (B), it is called Bai-u or earlier summer type and typhoon season or later summer type for the reversed case. A method of significant test at 20% level is applied for this judgement. For example, if (A) and (B) are 18 and 2 respectively among 20 occurrences, the difference is distinctly significant at 20% level. Generally the following frequency k is necessary for total number n to discern the significant difference between them at 20% level.
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When a difference between (A) and (B) is small, it is commonly insignificant and included in the mixed type. Fig. 1 shows the distribution pattern of these types. In entire Japan, the Baiuperiod type heavy rainfall spreads continuously in the western and northern part of Kyusyf and in western Chyugoku and also is scattered in limited areas in Hokuriku and Tosan (inland mountainous region from Gifu to Nagano Prefecture), while the typhoon period type develops in far wider regions.
3. Secular change of extraordinarily heavy rainfalls for the period of seventy years from 1901 to 1970 is examined. For this purpose the entire period is divided into seven equal intervals of ten years. In the next step, total sum of extraordinarily heavy rainfalls occurring at forty-one places in Japan are calculated as shown by the following series:
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For this time series, the secular trend is expressed by the trend index devised by E. Suzuki (1968).

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The demand and supply of water for irrigation in the area along the Minuma Irrigation Canal in the basin of the Nakagawa has been influenced since 1960 by the following factors:
(1) Completion of the Tone Grand Dam open to many canals
(2) Carrying out of the rice crop control
(3) Urbanization in progress
(4) Progress of ground-making works
(5) Increase in the number of irrigated lands
(6) Spread of the earlier cultivation of rice and of the direct sowiag of rice.
We were able to estimate in advance the surplus amount of irrigation water over the amount newly in demand. It turned out that surplus water had been brought forth by ruining rice fields because of urbanization and also by various administrative policies including the rice crop control. The way of water use, however, has not changed as much as that of the land use.
This resulted from the following three factors:
(1) It is not long since the way of water use came to be influenced by an administrative policy and by urbanization in progress accompanied by the change of the way of land use.
(2) The demand for irrigation water necessary for groundrmaking works has increased all the more for a selfish irrigation plan the plan for more and more frequent use of water, so that the whole system of irrigation has not yet been re-organized.
(3) The actual conditions of surplus water and the method of irrigation in the areas possessive of surplus water form technical and economical obstacles.
Not thatt the way of water use has not changed at all as that land use has changed.
Of course, it has changed not in the aspect of surplus water, but in the aspects of natural and historical characteristics of irrigation canals and of social characteristics of irrigation water for paddy fields. And also it has changed merely as a result of a shortage of water caused by the change of the agricultural use of land.

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By considering the land value along the streets as one of the elements which may indicate the character of the central shopping streets, it has become clear that the land values along the central shopping streets are associated with other characteristic elements on the streets, and that the extents of the central shopping streets in CBDs are controlled by the land value along the streets.
Making use of the land value along the streets, discussions treated here may be summarized as follows:
(1) There are three types of the central shopping streets (A, B and C) in view of the arrangement of the land value in each block along the central shopping streets.
(2) When the difference of the land value of the central shopping streets in CBDs is measured by the land value along the streets (peak of land value=100%), types of the central shopping streets can be divided into a, a' ………e.
(3) Types of the central shopping streets reckoned on the ratio of the length to the land value of each block along the central shopping streets can be divided into (1)_??_(5).
Next, the writer has tried to establish synthesized types of the central shopping streets from the above-mentioned characteristics of the land value along the. central shopping streets as fol-lows: Aa(1) for Sendai, Bc(1) for Takamatsu, Ae(4) for Gifu, Kôchi, Kôfu and Saga, Aa(2) for Sapporo, Okayama and Kokura (Kitakyûshû), Ba(2) for Hiroshima and Himeji.

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Deposited snow in the early stage of melting season has a complicated structures, with many different kinds of snow layers and ice-sheets. An ice-sheet in the snow layer acts as an impermeable layer for the downward moving free water and creates a water bearing layer on it. Horizontal movement of water in this water bearing layer is examined in this report.
In this experiment, horizontal movement of water is measured by using colored water. The relation between velocity of water and horizontal angle of snow layer is represented in Fig. 2, in which the velocity increases in proportion to the horizontal angle of snow layer. Large difference exists between lines A-B and C-D, which may be caused by the difference in texture of snow. Structures of the deposited snow at the time of these experiments are shown in Fig. 1.
For the comparison of this result, velocity of vertical seepage is obtained in Fig. 3. Horizontal movement of melted water in the snow layer is considered as an important factor of runoff in a mountainous region from the stand point of snow hydrology.

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