Characterizing pollutant loading from point sources to the Tongqi River of China based on water quality modeling

It is vital to elaborately understand the pollution sources in environmental management. Based on water quality modeling, one procedure was proposed to characterize the pollutant loading from point sources to environmental medium. It included four steps: (1) identifying the pollutants' discharging units (abbreviated as PDUs) according to the outlets distribution along the river; (2) based on the hydraulic characteristics of the river, dividing the river into several segments; (3) introducing the water quality model of the river with calibrated and verified modeling parameters; and (4) estimating and characterizing the pollutant load. The methodology was programmed and applied in characterizing the COD load from point sources to the Tongqi River of China. All point sources along the river were identified to be six PDUs. The temporal variation of the pollutant discharged from point sources could be described by the curves or functions in the procedure. COD load was at the peak of the curve from noon to dusk (about 10:30 a.m. to 8:30 p.m.), and from the midnight to the morning they were stable, at the bottom. This comprehensive understanding for pollution sources could be important in helping decision makers to schedule and control the pollutant load into the river.