Based on the physical mechanism of light transmission in water

the concept of water optical thickness is introduced into the transmission study

and then an integrated model for quantitatively calculating water depth by using remote sensing techniques was presented in this paper. Take Felaixia reservoir in Guangdong as a case study in this paper. Firstly

SPOT5 remote sensing data through radiation correction and atmospheric correction were converted into reflectance image in accordance with actual surface reflectance. Secondly

the information of waters was extracted by comparing the spectra of waters and lands

and then optical parameters of waters were substituted into the integrated models

selecting the appropriate bands of remote sensing

for calculating the water depths. Finally

the calculated water depths were input drawing software to generate the remote sensing map of water depths. The influence of sand mining and cage culture

such as turning muddy and high chlorophyll concentration of the reservoir waters

on the precision of water depth information has been considered in the model building in this paper

and hence multispectral remote sensing data were successfully applied to improve the calculation accuracy．