The surface currents of Lake Biwa-ko deduced from driftbottle experiments
スポンサーリンク
概要
- 論文の詳細を見る
The currents of lake water are very important in limnology, but the investigation for such problems had scarcely been carried out in this country.<BR>About thirty-five years ago in Lake Biwa-ko, Shiga Prefecture, the greatest lake in Japan, measurements by EKMAN current meter had been obtained by the staff of Kobe Marine Observatory for the first time and a series of three swirls, anti-clockwise, clockwise and anti-clockwise were observed from north to southward.For generation of such a current system, they had pointed out the three local wind directions, south to southeast, depending on the topographical condition around the lake basin, but the existence of these swirls have not yet been ascertained.<BR>In the summer season of 1960, we tried the drift-bottle experiments in Lake Biwa-ko to observe the surface current. On Aug. 12, we released 300 bottles from 6 stations, 5 of which stood on the cross line over the lake, and next time, on Sept. 2, 500 bottles from 14 stations on the longitudinal axis of the lake. The percentage of recovery was about 33% for the first time and 57% for the second. The distribution of drift-bottles recovered around the lake are tabulated in locality number and the frequency of recovery in each location as well as the drift time deduced from the time of recovery for the first bottle ashored are also described in the table.<BR>In the first experiment, the bottles released from STs. I and II were recovered in various positions along the coast in the northern part of the lake, and the bottles from the Stations III to VI are recovered only at the west coast. In the second experiment, some of the bottles released from the Stations I-1 to II were recovered only at the southwest coast. Such drift current may be assumed to set up due to the lake water effluent to the Seta River in the southwest end of the lake. Some of the bottles released from the Stations III to VI were recovered only at the southeast coast in narrow range and the tendency appears contrary to the first experiment. Although the bottles released from the Stations VII to X were recovered at the southeast coast in comparatively wide range, none was recovered at the north or northwest coast, where many bottles had been recovered in the first experiment.<BR>With reference to the wind direction at Hikone Meteorological Observatory, Locality No.9, on the east coast of the lake, it may be able to understand the difference between the both experimental results. In the first experiment, as the southeast wind was predominant, the drift-bottles had been flown nothward, but in the second time northwest wind was so predominant that the bottles could not easily flow northward.<BR>Though such a wind drift may apparently be considered, the lapsed time from release to recovery of the bottles are enormously divergent, as in Figs. 4 and 5, which may deduce the counter-clockwise circulating currents in the northern part of the lake. Velocity of the currents may be estimated 510cm sec<SUP>-1</SUP> from these experiments.
- 日本陸水学会の論文
日本陸水学会 | 論文
- キイロカワカゲロウの孵化におよぼす水温の影響〔英文〕
- キイロカワカゲロウ羽化の経日・日周変化〔英文〕
- Studies on Taxonomy and Distribution of the Freshwater Snails,Genus,Semisulcospia in the Three Islands inside Lake Biwa
- びわ湖南湖におけるタテヒダカワニナおよびカゴメカワニナの分布とその決定要因について
- ちりとり型金綱による河川底生動物採集上の問題点