Abstract
In this paper, the authors have tried to clarify some basic limnological features of three lakes called “Megata” in northwestern part of Oga Peninsula, especially aiming to compare the water quality in recent years with that about forty years ago (S. Yoshimura, 1936). This paper presents the result obtained by several surveys undertaken from 1973. Some results are summarized as follows:
a) From this investigation, the bathymetric maps as shown in Figs. 2, 3 and 4 were obtained.
b) In these three lakes, the water temperature gradient in thermocline in summer is higher than other lakes in Japan, and especially it is very high in Ichino-megata.
c) According to the result of the analyses, the water quality in Nino-megata is slightly different from that of the other two lakes.
d) A linear relationship is found to exist between the total amount of the precipitation in preceding winter and each content of Na+ and Cl- dissolved in the lake water in spring.
