To improve the safety of water intake and alleviate the waste heat pollution from thermal power plants, a new depth-averaged turbulent model (DEASM) based on explicit algebraic Reynolds stress model is developed to describe the whole thermal shallow flow. The algorithm of the turbulent model is based on SIMPLE procedure and discretized on unstructured grid. QUICK scheme is modified to improve the precision of advective flux approximation. The numerical results show that the simulated data by the model are well consistent with the experimental data, including section velocity, circulation streamline and the geometrical centers, flow diversion point and temperature distribution. The present depth-averaged turbulent model provides a detailed and unified pattern for solving the shallow thermal flow in adjacent and distant zones.