The ancient Otsu-Kyo was established by the Emperor Tenji on the southwest of Lake Biwa in 667 A.D.. The capital remained there for only five years until it was transfered to Asuka in the Nara basin. Regarding the scale or the accurate location of the Otsu-Kyo site, we have not obtained any accepted opinion in spite of much discussion by the historian Dr. Sadakichi Kita and many other scholars for over the past 50 years. Owing to the excavation of the site of the Sufuku-ji Temple, however, which is said to have been built by Tenji in the northwest of the capital, it has become unquestionable that the capital was situated somewhere around Shigasato, a little to the north of present Otsu City. Besides, in prewar days Dr. Jiro Yonekura, a historical geographer, considered this palace site to have adopted the Jori system of one cho (109m) square itself, but did not clarfy its scale. It is after the war, in particular, that old capitals of almost the same period, e.g., Fujiwara-Kyo (694-709 A.D.) in the Nara basin and Naniwa-Kyo (652-686 A.D.) in the Uemachi upland of Osaka, have been increasingly unearthened and that researches into the Jori or the Jobo allotment have been pursued accordingly under historico-geographical methods.
The present writer investigated in this paper the reason why in the region south of Lake Biwa, the Jori pattern of its western part where Otsu-Kyo had been built was found extending exactly north and south, in contrast with that of the eastern par following natural inclinationons by the lake. The author then proved that the land of the western part in question had been allotted as an extension of the Jori of Kinai districts, such as the western Kyoto and Yarnashina basins. Furthermore, it was found out that, as shown by the line AB in Fig. 1, the summit line about 500 meters high, leading to the south of Mt. Hiei, had been chosen as the north-south basic line, and that the line CD passing through Mt. Gyoja (440.6m) at a right angle to it, as the eastwest basic line. In Otagi-gun of Kyoto, namely, ancient Yamashiro province, there lay 15 jos from south to north, which has turned out to be also the case in Shiga-gun of ancient Omi province where Otsu-Kyo was placed.
In the second section, it was estimated that Otsu-Kyo was half as large as the early Naniwa-Kyo. To put it concretely, the capital formed a rectangle with the 10 cho (1090m) east-west side and the 15 cho (1635m) northsouth side, in the center of which there was a palace area of 5 cho (545m) square. In addition, the length of one bo was not equal to 360 shakus (109m) of the Jori system, but to 450 shakus (136m) of the urban Jori system. There were four bos recognized symmetric as in Fig. 3, as well as the main street running in the middle of the palace site.
Thus, the author regarded Otsu-Kyo as having been reorganized into the Jobo system, on the basis of the former Jori pattern. This study was made by means of the measurement of land pattern in Otsu-Kyo and the survey of the distribution of land names (Koaza) or of other micro land forms.
Although the duration of Otsu-kyo was no longer than 5 years, its city plan was carried out so completely that not only various official buildings but storehouses, schools and temples were also constructed. Moreover, the location of Otsu-kyo fell in with a starting point of the old Hokuriku Road. It occupied a very important place, inview of both land and water transportation, viz., with the roads leading to Kyoto, Asuka and Naniwa and with the outports, Karasaki and Hamaotsu on the lakeside, to utilize rivers such as the Uji and the Kizu.

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The River Takahashi, which flow through the west side of the Kurashiki city in Okayama Prefecture, had naturally brought about, from the Middle Edo period down to the Meiji era, not only flood damages invited by the collapse of embankment, but also such incidents as ill damage and lack of the water for irrigation, because its river bed had been higher than the plain on both sides of the river.
Tracing the period as well as the cause to all over the basin of the river Takahashi, and furthermore, scrutinizing the socio-economical circumstances at the times when such a change took place, the author here tried to clarify the conclusive cycle system between the river bed rising and its pertaining phenomena (Table 6th).
Summing up, there were zones of the Tatara_??_industry (sand iron industry by foot-bellows smelting process) at the valley of the upper stream Takahashi from ancient times. Stabilizing and extension of the embankment had already begun to develop the newly reclaimed paddy-field at the lower stream area from about the 15th century onward. Since then in the latter half of the 17th century several records came to be found in the ancient manuscripts, indicating that earth and sand which were washed down in the sand iron gathering process, increasing in quantity, had caused the river swelling; the more waste they flowed down after digging out, the more unwiedly it had been accumulating at the basin and shifted the delta toward the lower stream area. Physical aspects favourable for the newly reclaimed paddy-field development had been rebuilt up in such a way. In keeping pace with it, additional stabilizing and extension of the embankment accelerated the river bed swelling more and more.
In the latter half of the 18th century, enormous quantity of earth and sand were going to sweep away from the granite mountainous district in consequence of the reckless deforestation at the hilly countries, and the river bed of the Takahashi had been still continuing to swell higher. These rising of the river bed closely interrelated to the socio-economical fluctuating periods, and almost all their timing were coincidated with each other. The same process are found more or less at many other rivers which flow from the Tatara industrial zones such as the Chugoku mountainous district of Japan.

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