ClearWater-Riverine: An Integrated Water Quality Modeling Framework for Riparian and Floodplain Ecosystems

Watersheds comprise a complex web of interactions as water, heat, nutrients, and contaminants flow in varying frequency and quantities through riverine ecosystems. Integrated process-based riverine water quality models that incorporate these processes and interactions in river channels, riparian buffers, and floodplain ecosystems are needed to predict changes to watersheds due to stressors such as land use and climate change, as well as changes associated with beneficial actions, such as ecosystem restoration. ClearWater-Riverine, the U.S. Army Corps of Engineers Engineer Research and Development Center’s (USACE-ERDC) new state-of-the-art riverine water quality modeling system, simulates water temperature and water quality in branching river systems and floodplains, incorporating hydrodynamic, water quality, and meteorologic inputs from multiple sources, including hydrologic, hydraulic, and non-point models, climate models, and observed data. ERDC's Corps Library for Environmental Analysis and Restoration of Watersheds (ClearWater) provides water quality kinetics, heat budget, and transport simulation capabilities in ClearWater-Riverine. The ClearWater modules were developed to extend state-of-the-art hydrologic and hydraulic (H) modeling tools and has linked or integrated with several widely used USACE H models to simulate water quality in rivers, reservoirs, and watershed runoff. ClearWater-Riverine leverages two-dimensional Hydrologic Engineering Center River Analysis System (HEC-RAS) river-and-floodplain models to enable cost-effective, data-driven impact assessments, planning studies, and aquatic ecosystem restoration and management. To efficiently transfer data between models, ClearWater-Riverine uses open-source file formats that support large, complex, and heterogeneous data and metadata. ClearWater-Riverine's modeling framework links hydrologic, hydraulic, hydrodynamic, water quality, and vegetation models while providing data visualization and analysis capabilities. The integrated modeling system enables identification of system vulnerabilities as well as adaptation pathways that improve ecosystem resilience to environmental stresses, predicted to increasing due to frequent and intense extreme precipitation events and diminishing freshwater flows. This presentation will give an overview of the design of the ClearWater framework, modules, engine, and modeling methodology, the process of linking water resource models International Congress on Environmental Modelling & Software iEMSs with the water quality modules, and the data storage and exchange design and methods. An application of the integrated ClearWater-Riverine water quality model will be demonstrated, illustrating its benefits for effectively evaluating water quality impacts and designing ecosystem restoration projects.