A lot of submarine sand ridges were found in the East Channel of the Tsushima Strait by the survey which is one of the project of the Hydrographic Department, Maritime Safety Agency, Japan, named “the Basic Map of the Sea in Coastal Waters”.
These submarine sand ridges are classified into two types; one of which is U-type and the other is longitudinal type. The U-type sand ridges develop in the narrowest part of the channel between southernmost of Tsushima Island and Iki Island. The longitudinal type sand ridges extending northeastward develop abundantly in the vast area behind the U-type sand ridge area. From the relations between that regular arrangement of sand ridges and distributions of current velocity and grain size of sediments, the authors concluded that at the present these sand ridges are not in growing stage by the Tsushima Warm current, but have been made by tidal currents at a past age in which sea level lowered at the depth of -80 meters. It's inferred that in that stage, the narrowest channel was 40km broadening to 80km in the northeast; and moreover the pression about 40m-depth ran through the center over which 2-3 knot-tidal currents flowed. In these circumstances like the present Malacca Strait, both the narrower spacing sand ridges in the northeast shallow bottom and the broader spacing ones in the central depression were built up.
These sand ridges covered the submarine terraces at the depth of -90m to -120m. Accordingly, abundant submarine sand ridges are formed on the way of the rising sea level after the Würm glacial stage when -110m to -120m terrace cut presumably.

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The late Holocene deposits in the lowlands are subdivided into three regional pollen assemblage zones, i. e. Quercus-Fagus zone, Cryptomeria-Fagus-Quercus zone, and Pinus zone in ascending order, based on the occurrences of the regional temperate trees. The ages for the base of each zone are older than ca 6, 000y. B. P. for the lower, 2, 700-2, 000 radiocarbon y. B. P. for the middle, and ca 1, 000y. B. P. for the upper. From a comparison with the previous studies on the mountainlands, it suggests that Cryptomeria and Pinus have spread mainly in the lowlands, and these have not made an striking invarsion upon the Fagus forests in the mountainlands.

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The following has been become clear by my researches:
1) ‘Gentian Cultivation’ in Yokote Basin was started in 1971. The cultivation area increased rapidly in connection with the Reorganization Industry of Rice Feld Utilization and the Promotion Industry of Flower-Growing district in Akita Pref.
2) ‘Gentian Cultivation’ is accompanied with the agricultural conversion in Yokote Basin. The cultivation area is on the level ground from a topographical point of view. The magnification of the area in Ômagari-Senboku district is expected in future.
3) The technical introducers of ‘Gentian Cultivation’ are five now in Yokote Basin. The order of the introduction in the districts is as follows; Yuzawa-Ogachi district, Ômagari-Senboku district and Yokote-Hiraka district.
4) ‘Gentian’ cultivated in Yokote Basin are chiefly forwarded to the other Pref. markets. The cultivated ones in Ômagari-Senboku district are forwarded to the markets of Akita City, Hokkaido and Tokyo, and they show high profits. On the contrary, the cultivated ones in Yuzawa-Ogachi district are forwarded to the Tokyo markets only, and they show low profits.
In recent years, the supply of ‘Gentian’ cultivated in Akita Pref. has been increasing rapidly for Akita Fresh-flower Market.

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Kowakubi in Nishisen and Kotane in Kyowa are both located in Senboku, Akita Prefecture, and both of them are situated on the meandering parts of the Omono River. Some marked features of agricultural water supply in these areas are as follows;
Before 1925, people depended on river-bed lakes and irrigation ponds for irrigation water. In those days they often disputed about water-rights for want of water supply.
From 1926 to 1945, water was pumped up from the Omono River. and land improvement plan was carried out even under the unfavorable situations of the impoverished rural communities and World War II.
From 1946 to 1965, a strong desire for an agricultural production, awakened by the Agrarian Reform Policy by the Japanese Government, accelerated the progress of the land improvement plan, with a food supply increase program planned by the government.
In these areas, some geographical features had made the natural influx of water from the Omono River difficult. And they spent a great deal of money and labor in exploiting peat bogs and swamps.
The completion of both the prefecture-managed Kowakubi Pumping Machine and the main irrigative canal has afforded the ample and constant supply of water, and at the same time, has made the increase of rice production possible.
The improvement of agricultural water supply has greatly influenced these areas in their working conditions, habitual practices of water supply and house structures.

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Sciences whose philosophical and theoretical bases are given by the general system theory, are developed by some kinds of paradigms. A basic paradigm of modern geography that is underlying the general system theory may be the spatial diffusion theory. Studies about the cities may be defined as the studies to demonstrate the parts of the urban systems.
Urban system would be changed and generated by the diffusion of urbanization. It seems that the urbanization has four dimensions—urban growth, industrialization, emergence of middle class and the rise of the nationalism. The changes of those dimensions bring forth the changes of the social, economic, political and cultural systems which compose the urban system complex. However, those are nonspatial systems. Therefore, it needs that the nonspatial systems to project on earth-surface, and then they are transferred into the spatial systems as the models.
The urban system complex can be studied by setting the resolution level. And the urban system theory can synthesize two traditional approaches for study of cities; the one is the study of city as the system and the other is the study of the systems of cities. Three cardinal resolution levels of the urban system are distinguished to urban geographers; daily urban system, regional urban system and national urban system. Above the national level, we can see the world urban system as the whole urban system. Although a city, It is composed of many subsystems and latent interactions. They are elements of a city system, and at the same time, they are elements of the regional and national urban systems. Those various levels of urban system compose the hierarchical urban system as the whole.
On the viewpoints mentioned above, author would like to propose the present problems on the study of urban system,
1. The urban system should be analysed on the various resolution levels with many variables. On the basis of the outcomes of many analyses the urban system complex can be synthetically interpreted.
2. It is important that the demonstration of the growth patterns of urban system in accordance with the progress of urbanization by the time-serial study. To study the growth patterns of the urban system could contribute to solve the actual urban problems and could provide useful advices for planning.
3. The forcasting of the urban system in future is also important. It will be achieved by the synthetical study which includes the study of the urban system structure, shape, nature, boundary, dimension and the cause of changes along the time-serial axis. This may mean a study of the spatial diffusion effects of urbanization.
4. Finally, the relationships between the urban system and regional system in the integrated space system should be systematized and the hierarchical structures should be made clear in their systems.

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