Wola · the stretch of the walk along Towarowa and Okopowa
According to the description of a museum walk in May 2022, the route followed the former channel (to be checked in the source). This sentence can be read in two ways. Choose an argument and see whether it tells A from B. The drawings show only two hypotheses to check (a hatched band in A, a blurred band in B) and markers for the chosen argument; there is no line of a confirmed river, and blue is reserved for water described in the source (to be checked), which appears only in an inset about a different place.
Both readings are open.
Blue is reserved for water described in a source (to be checked), so there is no blue line on this stretch. Choose an argument above: you will see what it checks, whether it tells A from B and what it lacks.
It does not tell A from B.
What the source says. According to the description carried over from V2, Towarowa and Okopowa form a stretch of the walk along the former Drna channel. This points to a corridor of streets, not to the axis, width or banks of the channel.
On site. Note separately what the text says and what you see yourself.
It does not tell A from B.
What the source says. Nothing: this is not a source about the river. The edge of the asphalt belongs to today’s street network and does not say where the water flowed. Fitting the channel to the roadway would be an assumption, not evidence.
On site. Record the shape of the ground as an observation, not as a trace of the Drna.
It does not tell A from B.
What the source says. Nothing about the river. Covers and gullies are modern infrastructure. Not every gutter or wet hollow is a trace of the Drna, and a sewer under a street is not the same as a river.
On site. An observation from the pavement is enough. Do not open covers and do not step onto the roadway.
It does not tell A from B: this is a different place.
What the source says. According to the description carried over from V2 (to be checked in the source), the museum describes a preserved open stretch of the Drna by the Citadel. It shows that water is visible there, but it does not say where the channel lay on Towarowa and Okopowa. The blue wave in the box in the drawing is an inset about a different place, not water in this frame.
On site. Observe the bank from an accessible path. This page does not assess the accessibility or safety of the site.
It could tell them apart, but it is not in the material.
What the source says. Nothing, because no plan was supplied. Overlaying a plan requires control points recognisable both on the plan and today, and a statement of how far they disagree. The empty box in the drawing stays empty. See the model trial (an example, not data about the Drna).
On site. For every plan you find, note its scale and date; without them there is nothing to overlay.
The drawings in this section are our own schematic of one street stretch seen from above, not to scale and without coordinates. The hatched band (A) and the soft band (B) are hypotheses to check, the orange mark is the argument currently being checked (for the former plan: an empty grey dashed box, because there is no plan), and blue means only water described in a source (to be checked), and in a place other than the frame. The legend applies to drawings A and B; the axis of the model trial has its own legend.
02 · Model trial
A former plan could decide between A and B, but only if the river axis on the plan lies further from the street axis than the misfit of overlaying it on today’s map. The model below shows this with example numbers. These are not data about the Drna.
Model rule: A, when the whole interval fits within the roadway strip (±10 m, an assumption, not a measurement of Towarowa or Okopowa). Against A, when the interval lies entirely outside the strip. In all other cases both readings stay open. The scale of the axis is fixed for every setting: changing the misfit lengthens the segment instead of rescaling the drawing.
Both readings remain open.
The river axis could have lain from 5 to 55 m from the street axis; the roadway strip in the model reaches 10 m.
The misfit interval includes the edge of the roadway strip, so this plan does not settle whether the axis lay beneath the asphalt. Reduce the misfit or add control points to check this.
| 0 m, ±5 m | whole interval (−5 to 5 m) within the roadway strip: the plan favours A |
|---|---|
| 30 m, ±25 m | interval 5 to 55 m includes the edge of the strip: both readings open |
| 50 m, ±10 m | interval 40 to 60 m outside the strip: the plan argues against A |
03 · The route of the walk in three statuses
The route of the museum walk links three places with different evidential status. The type of line beside each shows how much the source actually says about water.
The content of this section is carried over from V2 and not verified in V3: check it in source 1 and source 2.
landmark · no watercourse
According to the museum’s description, the starting point of the walk in May 2022 (to be checked in source 2). The building is a meeting point, not evidence of a visible river.
walk corridor · position of the channel not established
According to the museum’s description, a stretch of the route along the former channel; further on, as the description states, through Żoliborz (to be checked in source 1). This is the place of section 01: two readings, no argument that settles it.
water described by the museum (to be checked)
According to the museum’s description, a preserved open channel (to be checked in source 1). The only place where this page uses the colour blue. It shows the presence of water today, but does not reconstruct the former width or floodplains. Photograph: link to Wikimedia Commons (not embedded).
The museum’s walking “river trip” in May 2022 was approx. 6.5 km (according to the museum’s description, to be checked in source 1). This is information about the event, not about the length of the river.
04 · Explanation and limits
This page does not draw the course of the Drna. It sets out two readings of one sentence from the walk description and shows which arguments tell them apart. In the material supplied none does, and that is a result, not a defect. Absence of evidence is not evidence of absence.
Sources · check the lead
Not supplied: a former plan with the axis of the Drna marked, scans, control points or data on the sewer network. The exact course of the channel and current conditions on the route require separate verification.
