Satellite analysis for water flow of Lake Inbanuma Original Research Article

Multispectral satellite data sets and site surveyed data was utilized for water quality assessment. Lake Inbanuma represents a complex situation of major optical constituents and emergent spectral signals for remote sensing analysis. As such it provided a good test of the combined radiometric correction methods developed for optically sensed satellite data. Based upon results of repetitive laboratory experiments we examined this region by several field campaigns synchronized date and time with satellite observations. As results, first, in proportion to increased chlorophyll content reflectance absorption appeared in the portion between 625 and 675 nm whereas near infrared peaked at approximately 720 nm. Second, the spectral ratio of red and near infrared reflectance was diagnostically useful for assessing high chlorophyll-a levels in regional water. Third, the chlorophyll-a based trophic state index, established by Carlson in 1977, was used to calculate the results from the field campaign data. Based upon those factors, two transformed Landsat Thematic Mapper data sets were digitally analyzed. The complicated pattern and direction of eutrophic/hypertrophic lake water flow resulting from the “open-and-shut operation”, was analyzed. Regional variances in trophic state index values were observed. Also, the over all change in the trophic state of Lake Inbanuma indicated a specific efficacy in the “open-and-shut operation”. The accumulation of these digitally analyzed data will aid in further understanding the appropriate intervals of operation and will contribute to more accurate regional environmental assessments.