琵琶湖南・北湖の交流特性

Abstract

It is very important for engineers to know how the alternating current between the south andthe north basin in Lake Biwa occurs there. There are seiches and density currents in main flowpatterns which control it. The period of 1st mode of the seiche is about four hours, but it seems tochange by water level.The probability for occurrence of seiches is related to both wind speed and wind direction.That is, when daily mean speed of wind exceeds 2 m/see, the probability for occurrence of seichesbecomes 0.5. Moreover, wind directions of NNE and SSW components contribute especiallyto the occurrence of seiches.The density currents occasionally happen in fall and winter season. The discharge due to thedeveloped density current, which flows from the south to the north basin, is about 2, 000, 000 m3/day.