Tensions in Practice: A local block can move the hazard¶
An invented runoff route
Imagine 6 units of unwanted runoff reaching two sites through connected channels. The invented routing rule sends 3 to each site when both paths are open, but all 6 to B if A is blocked. Compare a local barrier at A with capturing the flow upstream. The quantities merely expose the assumed routing; they are not flood-control calculations.
Protect the threatened local site
Reduce A’s immediate exposure with a control available there.
Reduce exposure across the boundary
Avoid counting a transfer of exposure to B as elimination.
Why these aims pull against each other
A local barrier can protect A without absorbing the incoming flow. Upstream capture addresses the selected shared source but requires suitable capacity and control beyond A’s boundary.
Choose an arrangement to see what changes and what remains difficult.
Arrows show the stated work, authority, or access paths. Position, length, and color do not measure time, risk, cost, or performance.
What this choice protects
What it costs
When it fits
Compare the arrangements
Block A locally
Close A’s route; under the declared rule the full 6 reaches B. Observe B as well as A.
- What it protects
- Protects A when upstream intervention is unavailable or slower to implement.
- What it costs
- Leaves the total 6-unit flow arriving at a site; B receives more than its baseline 3.
- When it fits
- Plausible as a bounded local response if A needs protection and the destination consequence is identified and managed, not hidden.
Illustration note: This is an editorial, deliberately bounded illustration. Its stated rules and any numbers are invented, not observations, recommended settings, or predictions.
Capture upstream
A stipulated upstream facility captures all 6 before either site. Captured material still needs safe handling.
- What it protects
- Removes the flow from both selected site paths under the stated capacity assumption.
- What it costs
- Requires upstream access, 6 units of capture capacity, maintenance and a safe destination for what was captured.
- When it fits
- Plausible only if upstream control and adequate capture/handling are feasible; otherwise the diagram is not an available option.
Illustration note: This is an editorial, deliberately bounded illustration. Its stated rules and any numbers are invented, not observations, recommended settings, or predictions.
What this illustration does—and does not—establish
The source establishes the structural tension; the concrete alternatives and their conditional costs are editorial synthesis. No arrangement is a universal recommendation.
- Migration is an unintended consequence of the initial local protection, made visible by this analysis; it is not a negotiated transfer to B. Once known, choosing the barrier requires taking responsibility for that consequence.
- Real interventions can dissipate some flow, open other routes or produce delayed effects. Neither conservation nor full capture is universal; both are explicit toy rules here.
Source entries
Risk Migration
Risk migration T 2 supplies the local tension. The setting, alternative arrangements, and stipulated consequences are editorial applications.
Absorb versus Contain (scopal)
The frame says only absorbing the pressure or containing at the system boundary avoids migration, but absorption (reduce demand) and system-boundary containment are often infeasible or far costlier than local controls.