The boundary problem
Site-scale groundwater models often struggle with boundary placement. Users search for flow lines, groundwater divides, streams, no-flow limits, or constant-head boundaries. In complex settings, these boundaries can be fragile.
The nested-model alternative
IGW-NET’s global base model and high-resolution spatial fabric make a different workflow practical: build a regional parent model large enough to include the dominant hydraulic controls, then create a local submodel inside it. The local boundary is derived from the parent solution rather than guessed locally.
Why remote errors matter less
A parent boundary does not have to be perfect if it is hydraulically remote. Boundary errors decay through the regional flow system. By the time they reach the local area, their influence may be small compared with local controls such as pumping, recharge, streams, and hydrostratigraphy.
Sensitivity test
If users are uncertain, shift the regional boundary and rerun the local model. If local heads, flows, capture zones, or plume paths barely change, the local decision is not sensitive to the exact regional boundary.
Practical rule
Do not fight for a perfect nearby boundary. Build enough regional context that the boundary becomes hydraulically remote.