Abstract
Remote sensing techniques have provided new scientific tools for measuring water qualities in the natural environment. Interpretation of the signals recieved by remote sensor may make it possible to assess the water qualities both in quantitative and qualitative way. As yet, however, little is known about the specific effects on the spectral reflectance of the water body. Laboratory and field spectro-metric studies, along with theoretical studies of bio-optics, are the means by which these characteristics will be defined.
This paper describes field experimental work which forms part of an overall program intended to identify effects of water quality measurement by remote sensing. The measurements of spectral reflectance just above and below the surface, and water quality measurements were carried out at Lake Kasumigaura. Correlation coefficients were culculated on the spectral reflectance and water qualities.
The results showed that :
(1) Water qualities were highly correlated with the spectral reflectance above the surface at the region of 720nm while the other regions showed insignificant results. However, correlation between spectral reflectance just below the surface and water qualities was significant at 540nm and 694nm regions.
(2) Improved correlation can be clearly obtained if we consider the ratio of reflectances R(λ), R(694)/R(442) and (R(442)-R(694))/(R(442)+(694)).
