To reveal the impact of urbanization on urban river systems, the Buji River Basin, a typical highly urbanized watershed in the Guangdong, Hong Kong and Macao Bay Area, was selected as the study area. Based on Landsat satellite images from 1988 to 2015, Google Earth high-resolution images from 2003 to 2017, the river system data in 2019, as well as literature on the river improvement projects of Shenzhen City since 1980, the characteristic indices of river channel change were constructed to evaluate the spatial and temporal evolution of the river in the process of urbanization using remote sensing data and GIS technology. The study shows that: 1) From 1988 to 2015, the land use/land cover types of the Buji River Basin changed dramatically, and the urbanization rate increased from 24.55% to 61.78%. Generally, the urbanization showed the spatial and temporal characteristics of "fast first, then slowed", "spreading from downstream to upstream", and "developing along the river then towards the periphery". With the development of urbanization, the improvement of the Buji River has gone through four stages: pre-improvement, flood control measures, flood control and ecological restoration measures, and dredging measures. 2) The spatial and temporal evolution of the river was affected by urbanization. The increase of population and GDP has a driving effect on the river channel change. Different urbanization processes in different places have had different impacts on the river system, and urbanization has had different impacts on the main stream and tributaries of the Buji River. 3) On the whole, from 2003 to 2017, the proportion of surface channel, bending coefficient of surface channel, and river surface rate of the Buji River decreased by 19.06%, 9.63%, and 1.79%, respectively, which were negatively correlated with urbanization level. The river bed hardening rate was positively correlated with urbanization level, with an increase of 6.47%. This study provides a reference and theoretical support for river improvement and flood control and disaster reduction in urbanized areas of China.
