Abstract:
Lyzenga’s depth invariant index (DII) method and Sagawa’s bottom reflectance index (BRI) method.
To evaluate the role of each method in Khanh Hoa waters, Tuan Le water, with a high seagrass
coverage and moderate turbidity, and Thuy Trieu Lagoon, with high biodiversity of seagrass species
and turbidity water, were selected as representatives. 70% of the survey data was used for ground
training data of seagrass (dense and patchy), muddy-sand and sand features and the interpretation
of both methods, whereas the remaining 30% of the survey data was used for validation of the
mapping results. The maximum likelihood classification approach was used to extract the seagrass
map and evaluated by overall accuracy as well as the Kappa coefficient. The processing results
show that, in Tuan Le water, using the DII method gives an accuracy of 82.1% and the BRI of
80.1%; and in Thuy Trieu Lagoon, the DII method has an accuracy of 80.67% and the BRI of
80.0%. These results demonstrate that both methods have high accuracy results in both areas, but
the method of BRI gives better results.
