Emission Control in River Network System of the Taihu Basin for Water Quality Assurance of Water Environmentally Sensitive Areas

As pollution incidents frequently occurred in the functional water areas of the Taihu Basin, Yangtze Delta, effective emission control to guarantee water quality in the Taihu Basin became the priority for environmental management. In this study, a new total emission control (TEC) method was proposed with an emphasis on the concept of water environmentally sensitive areas (WESAs). This method was verified in Wujiang District and the techniques can be concluded in three steps: (1) a 1-D mathematical model for the study area was established and the model was calibrated using field measurement data; (2) based on an analysis of administrative planning and regulations, WESAs were identified as the main controlling objectives for emission control calculations. The weighting coefficient of local pollution sources was investigated to discuss the effectiveness of TEC on water quality improvement at WESAs; and (3) applying the river network mathematical model, water quality along the river segments was simulated under different pollution control plans. The results proved the effectiveness of TEC in the study area and indicated that a 14.6% reduction in the total amount of ammonia-nitrogen (NH3-N), as well as a 31.1% reduction in the total amount of chemical oxygen demand (CODcr), was essential in order to meet the water quality standard in the WESAs.