Multi-temporal water depth mapping by means of Landsat TM

The water depth in coastal areas was assumed to be linear with the first principal component of the logarithms of the detected signals within the spectral bands of the satellite sensor. Hence, relative water depths (digital counts) were computed. Charts of absolute water depths were then derived by the application of several calibration points with known water depth. The charts produced in this way were compared with available sounding charts. Multi-temporal images were used to assess the quality of the method and to detect morphological changes.