Linking surface water and groundwater models within the WaterCAST Catchment Modelling Framework

摘要

Traditional catchment models developed for water management purposes tend to focus on one or other of surface or groundwater processes. Where both are represented, there is generally a bias in detail towards either surface or ground flow processes, with the other often represented in a simplistic manner. WaterCAST has been developed as a "Whole of Catchment" modelling framework to address these issues, with a robust and balanced conceptualisation and representation of surface and ground flow pathways. This has been achieved by integrating the 'quick' and 'slow' flow components from the E2 modelling framework with groundwater flow concepts from the 2CSalt model. WaterCAST is part of the Catchment Modelling Toolkit, and provides a decision support tool to assess how changes in catchment management influence the quantity and quality of runoff to receiving waters. This paper explains the structure and representation of hydrological flow pathways within WaterCAST. The flexibility of the subcatchment-node-link structure of E2 has been retained by redefining 2CSalt groundwater response units within the link/storage conceptualisation of WaterCAST. This will allow a greater level of surface water-groundwater interaction as the groundwater model components interface directly with the surface water components. This structure also enables a groundwater component library to be included, similar to the Rainfall-Runoff and constituent component model libraries in E2. Partitioning of the water flow into surface and subsurface flow, recharge and baseflow components allows water and constituent fluxes to be "tagged" and tracked through the sub catchment areas to the catchment outlet/s.