Technical challenges with BOD/DO modeling of rivers in Taiwan

Many rivers and streams in Taiwan receive significant BOD and ammonia loads from domestic and industrial wastewaters. These loads are characterized by excessive strength (high concentrations and wastewater flows) – often with great spatial intensity. In many cases, an additional significant load enters the stream before the upstream input is fully stabilized in the receiving water. The classic DO sag and recovery curve in rivers associated with single point source BOD loads (as found in most textbooks) are therefore rare in Taiwan’s rivers. As a result, a different modeling approach must be adopted to address technical challenges associated with modeling for water quality management in Taiwan. In this paper, the modeling results of two rivers in Taiwan are presented to demonstrate the associated technical issues and difficulties, as well as recommend further effort to meet these challenges.

► Spatial variable CBOD deoxygenation rates are needed for modeling rivers in Taiwan.
► Comparing model results of two rivers clearly demonstrates this need.
► Classic DO sag and recovery curves are missing in these rivers.
► Field data are needed to derive in situ CBOD deoxygenation and nitrification rates.