HE Hua-xiang, ZHOU Zu-hao, NIU Cun-wen, WANG Hao (State Key Laboratory of Simulation and Regulation of River Basin Water Cycle, Institute of Water Resources and Hydropower Research, Beijing 100038, China)

Abstract: Based on the dualistic water cycle theory, a distributed watershed water quality model called WEQ has been improved on the physical mechanism, including the processes of pollutant generation and flowing into river and so on. The improved WEQ is strengthened in its physical mechanism of pollutant from farmland, using MUSLE equation for reference to calculate the amount of soil erosion and coupling water quality and dualistic water cycle process in dynamic computation. Once the amount of water use from industries and lives in river or water storage in reservoir are changed, the changes of water quality load or concentration are considered. The model has been applied in the Nenjiang River basin to simulate spatial distribution rule of COD and ammonia nitrogen and water quality variation characteristics of river cross-section. The simulation results show that MSEQ=1.81, Re=37.4% in calibration period and MSEQ=1.45, Re= 33.8% in verification period. In order to ensure the simulation error within reasonable limits, the amount of pollutants should be adjusted with the investigation results and the river cross-section pollution load should be verified with the monitoring data.

Key words: dualistic water cycle theory, watershed distributed water quality model, construction model, Nenjiang River basin

Published in: Journal of Hydraulic Engineering, Vol. 44, No. 3, 2013