Abstract:Due to the special terrain of Chongqing City, various types of drainage trunks have been built along the Yangtze River and Jialing River. Once pipeline bursts, it will endanger the water quality of downstream water intake. After the impoundment of the Three Gorges Reservoir to 175 meters, aiming at the sudden water pollution that may occur in in Chongqing Section of Yangtze River, a two-dimensional hydrodynamic water quality coupling model was built based on the measured topographic and hydrological data, and using optimal inversion method to determine the roughness. The finite element method is used to simulate the temporal and spatial variations of pollutant concentrations (BOD5, COD, TN, TP) under the conditions that the fractured pipeline was completely repaired after 24h or 48h in the high and low water periods. The simulation results can provide a scientific basis for the optimization of the emergency plan under the sudden drain pipe rupture in Chongqing.