GeoLinkage2.0 and GeoChecker: Hydroinformatics tools for large and complex hydrological-hydrogeological models using WEAP-MODFLOW. Case Study: Severe drought in the Limarí River Basin, Chile

Understanding and modeling surface and groundwater resources are critical due to the effects of droughts and climate change, especially in semi-arid, arid, or hyper-arid regions. GeoLinkage, developed by Troncoso (2021), facilitates the creation of linkage files for integrated models. These linkage shapefiles act as a communication interface between a surface hydrological domain (D₁) and an aquifer domain (D₂). The surface domain (D₁) comprises nodes and arcs that represent hydrological elements and their relationships, while the aquifer domain (D₂) contains geometric elements such as grids or Quadtree diagrams. D₁ defines a surface topology (τ₁), D₂ defines a groundwater topology (τ₂), and the linkage file establishes a surface-groundwater topology (τ_1-2). This new topology, τ_1-2 ,imposes constraints that influence the relationship between τ₁ and τ₂. For instance, the superposition of elements in τ_1-2 should be considered a spatial relationship. Depending on the type of superposed elements, this relationship must be reflected in τ₁  or τ₂. To enforce these τ_1-2 specific restrictions, GeoLinkage has been enhanced with a post-processing module called GeoChecker. This module evaluates the quality of the resulting linkage files. GeoChecker currently performs a superposition check to ensure that overlaps between cells in the linkage file—whether between groundwater and catchments or groundwater and demand sites—are accurately represented as connections in the surface model (WEAP). The aquifer is represented by a MODFLOW model fully linked to the WEAP model. GeoLinkage2.0 and GeoChecker were developed using the tutorial WEAP-MODFLOW model, considered a small model, and were tested in large integrated models, such as the Azapa Valley (3,000 km²) and the Limarí River Basin (12,000 km²), Chile.