we presented a newly regional three-band model to estimate Chla（Chlorophyll-a） directly by a case study in Taihu Lake and Shitoukoumen Reservoir.Inherent optical properties of the target waters were investigated to determine the model coefficients describing the relationship between three-band combination and Chla concentration.Results show that the proposed model is intended to both provide high accuracy and greatly reduce the uncertainty caused by regression algorithms.Based on the accurate and long-term water optical observations

the regional three-band models designed for different water areas would promote the operational monitoring of Chla in inland waters.