A series of reservoirs have been and are being constructed in the Lijiang River, Southwest China to regulate the flows. The operation of these reservoirs, mainly for flood control in wet season and tourism cruise improvement in dry season, dramatically altered the hydrological regime in the downstream, thus imposed significant impacts on the aquatic ecosystem.
The evolution of riparian vegetation is an important indicator to quantify these impacts. This research focuses on the understanding of the vegetation dynamics and the succession of the riparian zones due to the flow regulations by the reservoir operations. The study developed an integrated model which couples a two-dimensional hydrodynamics module with a vegetation evolution module. Owing to the ability to represent spatial heterogeneity and local interactions, the vegetation module used the unstructured cellular automata (UCA) method, which implemented a triangular grid. The developed model was calibrated by the historical vegetation data and the field observations. After calibration, the model was applied to a typical reach of the Lijiang River. Through the simulations, the previous changes of the riparian vegetations were analyzed and their future developments under the new flow regulation scheme were predicted. In particular, the potentials of UCA in ecosystem modelling were well illustrated through the study.