CCHE2D Water Quality and Chemical Model Capabilities and Applications

According to 1998 Clean Water Act Status by USEPA, sediments, pathogens, nutrients and metals are leading pollutants for rivers, streams and creeks. To study those water quality problems efficiently, it is necessary to develop a comprehensive model framework based on physical, chemical and biochemical processes. CCHE2D model has been developed for this purpose, which comprises of five independent models: two-dimensional depth-integrated hydrodynamic model, cohesive and non- cohesive sediment transport models, water quality (eutrophication) model and chemical fate and transport model. The eutrophication model simulates eight variables representing nitrogen, phosphorus, dissolved oxygen, and carbon cycles. The effect of suspended sediments on the phytoplankton growth is taken into account. The chemical fate and transport model simulates physical transport process and chemical fate processes such as sorption/desorption, evaporation, hydrolysis, photolysis, and bio-degradation. Both models solve the transport equation. The numerical scheme has been verified using steady and unsteady analytical solutions. Models have been validated using field measurements. Their applications are shown in this paper as well.