The Toko River Low]and, about 10 km long from south to north and 5 km wide from east to west, is located in the northeastern part of Hokkaido Island. The plain mainly consists of alluvial sediments of the Toko River, which are classified upper alluvial surface (Tosa surface) and lower alluvial surface. The upper alluvial surface is dissected in its northeastern part and composed of sandy sediments covered with Tokoro Volcanic Ash I-IV. The lower alluvial surface distributes along the Tokoro and Rai-Tokoro Rivers and its sediments are composed of sand and peaty silt. The geomorphological history of the Tokoro River Lowland in the latest Pleistocene and Holocene Periods is inferred as follows; (1) In the latest Pleistocene, former fluvial valleys were drowned by transgression and were filled with sandy and silty sediments. (2) In the early Holocene, sand spit or sand bar was formed at the mouth of embayment. (3) With progress of transgression, an embayment had extended to the southern part of the lowland. And very fine sediments such as clay and silt are deposited in the bottom of the lagoon. (4) A delta composed of sandy sediments was formed towards the northern part of the lowland around 5,500 y. B. P. (5) About 4,000 〜 3,OOO y.B.P., a slight regression caused dissection of the delta and formed Tosa surface. (6) After following transgression, the lower alluvial surface was formed covering with peat and silty sediments.
Dewa Hills in Yamagata Prefecture is composed of three mountainous regions: the Chokai Volcano, Dewa Hill (in the narrow meaning) and the Gassan Volcano. The mountains are dissected by several rivers, such as the Nikko-gawa R., the Aisawa-gawa R. and the Tachiyazawa-gawa R. These are representative of the each region mentioned above in the order. The present investigations have been conducted with the aim at elucidating the hydrological and geochemical features of the rivers by comparing each other. The results are summarized as follows: 1. The Nikko-gawa R. forms parallel basin composed of two featherlike basins. The drainage basins of the Aisawa-gawa R. and the Tachiyazawa-gawa R. are radial and featherlike respectively. Therefore, the average basin width of the Tachiyazawa-gawa R. is minimum. 2. In regard to the development of the tributaries, the first and second laws of Horton are applied to the above mentioned rivers. The bifurcation ratio of the Nikko-gawa R. is nearly equal to that of the Tachiyazawa-gawa R. The same is true for the length ratio. 3. Concerning to the quality of water, the main dissolved constituents in the Nikko-gawa R. and the Aisawa-gawa R. are sodium bicarbonate and sodium chloride due to the influx of the oil field brine in the drainage area. Different from these rivers, the dominant dissolved mineral in the Tachiyazawa-gawa R. is calcium sulfate which is supplied with the upper reaches subjected to the solfataric action of the Gassan Volcano. 4. According to the yearlong observation of the quality of water, the mean annual concentrations of Na^+, K^+, Cl^- and SiO_2, are in the following order: the Aisawa-gawa R. ≧ the Nikko-gawa R. ≧ the Tachiyazawa-gawa R. But in the case of Ca~<2+> and S0^<2->_4, the different order is found to exist: the Tachiyazawa gawa R > the Aisawa-gawa R. > the Nikko-gawa R. 5. The quality of water of the rivers has been statistically kept constant for these thirty years. 6. The transportation of total dissolved minerals and individual constituents in the streams was observed in 1979 fiscal year. A simple relationship is found to exist between each mineral discharge (Q_d) and flow rate (Q): Q_d=aQ^n, where a and n are constants dependent on the ion and the river. Regarding the same ion, the n value of the Nikko-gawa R. is nearly equal to that of the Tachiyazawa-gawa R. 7. Annual total discharge per unit drainage area (km^2) is estimated at 100 tons for the Nikko-gawa R. and the Tachiyazawa-gawa R. and 200tons for the Aisawa-gawa R. The annual amount of transportation of individual constituents is in the order: Na^+<Ca^<2+>, HCO^-_3>C1^->SO^<2->_4 for the Nikko-gawa R. and the Aisawa-gawa R. ; Ca<2+>>Na^+, HCO^-_3>S0^<2->_4>Cl~- for the Tachiyazawa-gawa R.
At present the total number of the ponds above I ha of benefited area in Japan is about 97,500 and the benefited area about 1,140,000 ha. The authors have analyzed their development, irrigation, conservation, maintenance and policies. (1) A large number of them are situated in some prefectures along the Inland Sea of Seto from the Kinki district. The reason is, it seems, not only there is frequent rainfall, but also they have no large rivers for water sourses, though they have the land fit for paddy field, and people there have relied upon ponds. (2) To consider periods in which those ponds were built. Before the Edo period, were built in the Seto-Inland-Sea district (e.g. prominently in Kagawa Prefecture) and the Kinki district; and they were distributed sporadically in Aichi and Fukushima Prefectures. After the Edo period, were built in the northeastern part of Japan and fewer in the southwestern part. After the World War II, large reservoirs were made in the valleys by the modern-type dams and the benefited area per one reservoir was strikingly extended. (3) At present, 87% of the total number of the ponds are small-scale ones with the capacity of less than 30,000 m^3. Building and maintenance of them are made dominantly by buraku (or village communities) or water-use associations in accordance with the buraku administration. But the maintenance has been made difficult by decreasing the function of the rural communities, due to either depopulation of the farmers, in the case of the ponds in the remoter areas, or the increase in the number of worker farmers and transferred uses for houses and factories, in the case of the ponds in the urbanized areas. (4) Present study, it was emphasized to increase of their uses as living environments: multipurposes, such as their uses as landscapes, drainage, open space or fire water, should be considered. It is expected that we should establish systematic scheme for their appropriate management by local governments. (5) To consider the improvement situations of the ponds in relation to natural hazards. Old ponds built before the Edo period are as many as 34% of the total ponds, but only 20% have been improved. Many of them are situated in the southwestern part of Japan where earthquakes, typhoons and land slides occur more frequently. So the authors have proposed that local government should not only proclaim the maintenance regulations of the ponds, but also check their uses and conservation periodically based on the standard of the classified measures for conserving them against natural hazard.
In the 10th year of Genroku, the Shogunate ordered the chief Daimyo (feudal lord) in each province to revise the Kuniezu (the map of each province). At the time of this revision, much importance was attached to the drawing of boundaries of Kuni (province) and Gun (county). The Shogunate map officers inspected each Shitaezu (the revised rough Kuniezu) to find out whether their boundaries were in accord with the boundaries of the neighboring provinces. The inspection of the Shitaezu became especially strict during the middle of the undertaking. A few of the Kuniezu had already been revised when this change in the way of inspection occurred. Such being the case, the early revised Kuniezu was not always detailed enough. Therefore, further additions had to be made (Kafumi) to the boundaries marked on the Kuniezu. In this paper the author revealed the process the revision of the Sendai Han (feudal clan) Kuniezu as the example of Kafumi. The Sendai Han Kuniezu was first revised quickly in the 12th year of Genroku. But just after the new Sendai Han Kuniezu had been presented to the Shogunate, Kafumi was ordered. Sendai Han tried to ascertain the boundaries with its neighboring clans once again and again exchanged the boundary maps with those clans. Additions were made (Kafumi) to the Sendai Han Kuniezu after a reinspection of the exchanged boundary maps. It was in the 14th year of Genroku that Sendai Han completed the revision of Kuniezu.