Closure-Horizon Dashboard¶

Live monitoring instrument — instantiates Managed Retreat

Fuses front position, remaining viable width, corridor health, and trigger status into one continuously updated read of how much time the option to retreat still has.

A Closure-Horizon Dashboard is the live instrument that answers one question continuously: how long does the option to retreat stay open? It fuses the moving pieces of the closing geometry — where the advancing front is and how fast it moves, how much viable width remains, whether the corridor is still healthy, how the estimate compares to the transition's lead time — into a single, always-current view, and tracks whether the retreat trigger's conditions are being approached. Its defining move is integration over time: not a one-off forecast but a monitored horizon that updates as the front behaves and the transition progresses, so a team watches the runway shrink rather than discovers it gone.

Example¶

A shoreline road serves a small headland community, and the bluff beneath it is eroding. A Closure-Horizon Dashboard pulls together the pieces that decide when relocation must begin: the erosion front (survey and lidar deltas showing meters per year, with a wide uncertainty band after each storm), the remaining viable width between bluff edge and the road's minimum safe setback, the health of the single access corridor, and the lead time the relocation itself needs — land, permits, construction — call it ≈4 years. The dashboard's headline is not "the road is fine" but a horizon: at the current closure rate the orderly-retreat window closes in roughly 5–7 years, against a 4-year transition — margin is thin and shrinking after each storm season. When a severe winter accelerates the front, the horizon contracts on the display and the trigger status moves from "watch" toward "commit," turning a slow, invisible loss into a visible countdown the community can act on.

How it works¶

Fuse, don't list. Front speed, viable width, corridor health, and lead time are combined into one horizon, because the danger lives in their relationship, not any single gauge.
Carry uncertainty on the face. The horizon shows as a band, not a false-precise date, so a wide band reads as "decide sooner," not "we have until the midpoint."
Update continuously. Each new survey, storm, or completed wave revises the horizon, keeping it a living estimate rather than a stale plan.
Surface trigger proximity. It shows how close the retreat trigger's conditions are, converting a slow squeeze into an approaching, legible threshold.

Tuning parameters¶

Refresh rate — how often inputs update. Frequent refresh catches acceleration early but can produce noisy, alarm-prone swings; slow refresh is calmer but risks lag at the worst moment.
Uncertainty display — point estimate vs. band vs. worst-case line. Showing the band resists false confidence; a single number is legible but misleading when the front is nonlinear.
Aggregation vs. detail — one headline horizon vs. drill-down into each driver. Aggregation aids decision; detail aids diagnosis; over-aggregation hides which driver is closing the window.
Alert thresholds — where "watch" becomes "commit." Tight thresholds prompt earlier action but risk crying wolf; loose ones risk reacting too late.
Horizon basis — whether the countdown runs to physical closure, to the last safe start of the transition, or to political/funding unavailability. The chosen basis changes what the deadline means.

When it helps, and when it misleads¶

Its strength is that it defeats the archetype's core enemy — invisibility, the slow closure no one acts on because no single day looks decisive — by rendering the shrinking option as a continuously updated countdown against the transition's real lead time. It also gives every other mechanism a shared common operating picture^[1] to plan against.

A crisp horizon invites treating a nonlinear front as if it declined smoothly, so a cliff — a storm, a threshold collapse, a sudden funding withdrawal — arrives long before the extrapolated date. Constant refresh can breed alarm fatigue until the display is ignored, or the reverse: a horizon quietly re-based on optimistic assumptions to make the window look comfortably far off, run backwards to justify delay. The discipline is to show the uncertainty band honestly, stress the horizon against discontinuities rather than trends, and tie action to trigger proximity rather than to the comfortable midpoint of the estimate.

How it implements the components¶

wavefront_indicator — it tracks the advancing front's location, speed, intensity, and uncertainty as a primary input.
closure_horizon_estimate — it computes and displays when the viable window closes relative to the transition's lead time — the dashboard's headline output.
converging_boundary_model — it represents the front, the rear constraint, and the shrinking viable band together, so their relationship is visible.
retreat_monitoring_and_update_loop — it is the continuous loop that revises all of the above as conditions change, keeping the horizon live.

It surfaces how close the trigger's conditions are but does not define the trigger or rehearse acting on it — that's Retreat Trigger Exercise. It shows corridor health but does not keep the corridor open (that's Controlled Corridor).

Instantiates: Managed Retreat — the monitoring instrument that keeps the closing horizon visible to every other step.
Consumes: corridor-health signals from Controlled Corridor; front, survey, and forecast feeds.
Sibling mechanisms: Retreat Trigger Exercise · Migration Wave Plan · Controlled Corridor · Setback Requirement · Receiving-Zone Reservation

Notes¶

The dashboard informs the retreat decision but does not make it: it shows the horizon and the trigger's proximity; committing to withdraw is the trigger rule's job, exercised by the Accountable Retreat Authority. A dashboard mistaken for a decision lets a team watch the window close in high resolution without ever acting on it.

References¶

[1] A common operating picture — a single shared, continuously updated situational view — is standard practice in emergency and military coordination precisely because dispersed actors otherwise plan against divergent, stale pictures of the same front. ↩