Taking the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) as the research area

this study 1) considered the interaction between water ecology and human society

internal and external environmental changes

2) constructed an index system that can reflect the water ecological state of the GBA more comprehensively

and 3) quantified the water ecological state of the GBA and its evolution trend from 2010 to 2019. Concerning the water ecology risks faced by the GBA

seven driving factors were selected

such as the annual runoff of the Xijiang River and the Beijiang River

the downstream tidal level

and the urbanization rate of the GBA. Taking the driving factors as the input and the four water ecological state indices as the output

the water ecological state reactor of the river network urban agglomeration in the GBA was constructed and its driving mechanism was studied. Results showed that 1) the water ecological state of the GBA has been improving in the past ten years; 2) the aquatic state was greatly affected by the annual runoff of the Xijiang River and downstream salinity; 3) the habitat index was under the rapid urbanization which shows a downward trend

but the rate of decline has slowed year by year; 4) meanwhile

rapid urbanization has shown an improvement of urban sewage treatment and effective control of the salt tidal upward

which has a positive impact on the improvement of the water quality in the GBA; 5) the water security of the GBA continues to improve despite the influence of changes in the diversion ratio and natural disasters.