Comparison of Two Models for Calculating Water Environment Capacity of Songhua River

Abstract

Water environment capacity is an important conception in environmental science. As a basic theory applied in EIA (Environmental Impact Assessment), water environmental capacity is also an indispensable factor in making District Environmental Planning and total water pollutant control. With the statistic monitoring data of 17 water quality indexes from 2001 to 2005 of six monitor sections offered by Harbin Environmental Protection Administration, assessment of water quality of Songhua River along Harbin City was made. Sensitivity analysis was performed to identify the critical model parameters from 17 indexes. COD and NH₃-N were selected as the key parameters to be calculated. Both one-dimension and two-dimension water quality model were calibrated and used to derive the water environmental capacity in Songhua River. Discussion was developed to show the model performance evaluation. The conclusion was generated that two-dimension water quality model provides a more conservative water environmental capacity than one-dimension model. There is no water environmental capacity in Harbin City region of Songhua River, which needs pollutant reduction. Up stream and down stream of Harbin City can bear with the current wastewater discharge.