Category: Physics

Summary: Estimating when stronger channelization feedback reorganizes subglacial drainage from diffuse sheet flow into a bridge-like upstream-to-downstream transport mode.

Subglacial drainage beneath ice sheets can move water through broad distributed sheets, through more concentrated channels, or through mixtures of the two. This experiment asks for the point at which channelization and effective-pressure feedback become strong enough that the dominant drainage pattern stops looking diffuse and instead forms a balanced bridge between upstream and downstream regions.

The script builds dense disordered drainage operators that represent sheet transport, channelization feedback, and their competition. It then uses iterative deepening and repeated dense eigensolves to bisect the feedback strength across system sizes from N=64 to 2048, tracking when the leading mode becomes a bridge-localized sheet-channel structure rather than a sheet-dominated one.

That matters because the transition is about how drainage reorganizes, not just about whether water flux increases or decreases. The docstring frames this as a threshold map that has not been systematically charted in this dense finite-size form, even though the broader ingredients are well studied in glaciology.

Method: Dense symmetric eigensolves with iterative deepening and bisection on channelization-feedback strength in disordered subglacial drainage operators across N=64 to 2048.

What is measured: Critical channelization-feedback threshold, bridge-localization of the leading mode, sheet-versus-channel dominance, leading eigenvalue behavior, and bracket width.