抄録
Land cover changes around lake basin have caused aquatic environmental degradation such as eutrophication or water pollution. In particular, increase of nitrogen and phosphorus components to the lake due to land cover changes of surrounding areas has been serious. Estimating influent loads from lake basin to the lake through rivers is very important in the management of lake environment. In this paper, the relation between total amount of nitrogen to the lake and land cover distribution was investigated with remote sensing. Lake Kasumigaura was selected as a test site for the case study.
LANDSAT MSS data from 1979, 1984 and 1990 were analyzed to produce land cover distribution map of the area. Land cover categories include urban area, paddy field, forest area and field. Lake basin areas were delineated with DEM for individual rivers to the lake. And the relation between total nitrogen of rivers and land cover distribution at the lake basin was analyzed. As a result, it was found that urban area and field in the land cover categories gave influence to the eutrophication of Lake Kasumigaura. Furthermore, in order to evaluate total annual pollution load (total nitrogen) to Lake Kasumigaura,
(1) basic unit of total nitrogen load for each land cover categoris
(2) influent annual total nitrogen to the lake were estimated from land cover change patterns from MSS data and from the total nitorgen concentration measured at each rivers to the lake.
