Estimating temporal and spatial variations in water clarity at Lake Tahoe, California-Nevada, using ASTER multi-spectral remote sensing data

A new method for measuring spatial variations in water clarity at Lake Tahoe was developed and tested based on light reflected from the lake bottom at three near-shore training areas. A series of ASTER images spanning four years were selected for this study. A band ratio was applied to the image data to isolate water-leaving radiance and minimize the effects of specular reflectance (sun-glint). Spectrally processed data were converted to a GIS compatible format and then incorporated into to a 3-dimensional model of the lake for analysis. The maximum depth of visibility (MDV) was determined for each training area by intersecting select ASTER image contours based on discrete band ratio values, with bathymetry contours. MDV values were then compared with their respective band ratio values in an attempt to determine if the spectrally processed ASTER data could be used to study water clarity across the entire lake.