Vistula · official main stem

Gauge coordinates and current discharge come from the named national hydrometric networks. The shared distance axis projects those GPS stations onto the dashboard’s sparse upstream-to-outlet spine; this is a profile axis, not surveyed navigation kilometre. The bed is published operator gauge datum throughout. A station whose register publishes no datum is left off it rather than given the spine’s interpolated height, which on a concave long profile sits well above the real bed. River power is gravitational power carried by the flow (ρ·g·Q·Δh), not metered generation - it is a floor rather than a total, because a reach whose downstream gauge reports no discharge contributes nothing. The navigability line is an indicative planning threshold, not an official fairway forecast.