Collection and analysis of water temperature data as the basic material for the study of global warming and aquatic environment

最近全球变暖的趋势已经从气候数据中得到了广泛的认识。湖泊和河流等内陆水域也受到气候变暖的影响，但验证这一趋势的数据并不充分和不完整。本项目收集了日本20世纪下半叶的水温资料。关于湖泊的数据来自(1)县政府发布的水质年度报告，以及(2)大学和水文学或湖泊研究所的观测。关于河流的数据来自(1)农业部进行的调查，(2)来自水温研究所报告的数据。地下水数据由千叶大学提供，可以说，近期的气候变暖已经对湖温和湖泊循环系统产生了影响。日本和其他地区的湖泊结冰天数也有所减少。本研究总结的基本资料将对讨论全球变暖导致的水环境变化具有重要意义。

Recent trends on the global warming have been widely recognized from climatic data. Inland waters such as lake and river are also affected by the warming, but the data to verify the trend are not sufficient and incomplete. Water temperature data in the later half of 20^<th> century in Japan were collected in this project. Data on lake are taken from (1) Annual report on water quality published by prefecture offices, and (2) Observation by universities and institutes on hydrology or limnology. Data on river are summarized from (1) Investigation made by the Ministry of Agriculture, and (2) Data from the report by Institute of Water Temperature. Data on groundwater were supplied from Chiba University.It can be said that the recent climatic warming has already influenced on lake temperature and lake circulation system. Numbers of days with ice cover of lake have also reduced in Japan and the other regions.The basic material summarized in this study will be important in discussing the change of water environment due to the global warming.