Atlas of Discoveries · catalogue V3 · Sonnet

The river that appears after rain

The thin line is water in the diagram. In the drawing of the valley there is none.

Wodąca Valley, Kraków–Częstochowa Upland (Polish Jura). According to the sources there is no permanent watercourse here, and the name “wodąca” refers to dry valleys. What on the floor of such a valley tells us about the path of water?

Drawing of a valley without water, with five numbered trace locations Our own illustrative drawing: a flat, grassy valley floor between two wooded slopes, with limestone rocks on the right. On the floor are five numbered places: tilted grasses, rubble, silt, a fissure and smooth turf. There is no water or channel in the drawing. The lower edge is deliberately ragged, because the general diagram begins below it.
What tells us about the path of water when no water is visible? This is our own illustrative drawing, not a photograph or a map. The water is left out on purpose. The positions of the numbers are conventional. The photograph of the valley (Commons, CC BY 3.0) is only a link.

Five traces, one caution

Choose a trace to see what can be concluded from it.

Without JavaScript all five descriptions are expanded alongside.

  1. Tilted tufts of grass
  2. Sharp rubble without fine sediment
  3. A thin layer of silt
  4. Fissure or sinkhole
  5. Smooth turf, no traces

No trace selected. The descriptions below say what one can look for on the floor of a dry karst valley. They do not claim that these traces occur in Wodąca Valley or that anyone has confirmed them there.

Illustrative drawing, not a photograph. Arrow: slope of the floor.

1 · Tilted tufts of grass

What you see
Blades and tufts bent in one direction, along the slope of the valley floor.
Cautious interpretation
It may be a trace of water flowing over the surface. Grass pressed down by wind, snow, animals or people looks the same.
What it does not prove
When it happened, or whether water flowed here at all. A single such trace is not yet an “episode”.
Corresponds in the model to
runs off: what neither stayed nor soaked in flows on down the valley.
Illustrative drawing, not a photograph.

2 · Sharp rubble without fine sediment

What you see
Sharp-edged fragments of limestone on the floor, with little fine material (soil, sand) between them.
Cautious interpretation
It is sometimes explained by flowing water washing out the fine material. Rubble also collects at the foot of rocks without any watercourse.
What it does not prove
That water flowed this year, or how strong the flow was. The process should be identified by a geologist.
Corresponds in the model to
runs off: runoff able to carry material is the part of the water that flows along the floor.
Illustrative drawing, not a photograph.

3 · A thin layer of silt

What you see
Dried fine sediment on leaves or in a shallow hollow, sometimes cracked after drying.
Cautious interpretation
It may indicate that water stood or flowed very slowly and left fine particles. A puddle after a single rain leaves such traces too.
What it does not prove
How much water there was, or whether it was a watercourse spanning the whole valley.
Corresponds in the model to
stays: water held in place, in hollows and in the soil.
Illustrative drawing, not a photograph.

4 · Fissure or sinkhole

What you see
An opening in the floor, or a hollow with an opening, with no standing water inside.
Cautious interpretation
In karst, water often disappears into fissures and sinkholes, so such an opening may be a place where water soaks in.
What it does not prove
Where the water goes next, how much it takes, or whether the opening is passable. The model does not indicate any swallow holes in Wodąca Valley. Do not enter openings or hollows, and do not assume that their edges are stable.
Corresponds in the model to
soaks in: water taken in by the fissures of the limestone leaves the surface.
Illustrative drawing, not a photograph.

5 · Smooth turf, no traces

What you see
Dense grass with no tilting, sediment or rubble.
Cautious interpretation
This is an observation too. According to the sources the valley floor has no permanent channel, and after ordinary rain water may stay in the soil or soak in without leaving a trace on the surface.
What it does not prove
That water never flowed here, or that it never will. No trace does not mean no water.
Corresponds in the model to
stays and soaks in: water disappears from the surface before it has time to flow.

AboveDrawing of the valley: traces are there, water is not. This is intentional.

Missing: no documented photograph of the valley while it carries water was supplied. The page does not draw water in its place.

BelowGeneral diagram for karst: conventional numbers, unrelated to any specific place.

General diagram · arbitrary units · not this valley

Where a portion of water can go

Each of the three sections of the valley receives the same amount of rain. A section first holds some of it, then absorbs some, and passes the rest further down. We show three kinds of ground at once, on one scale, so that it is immediately clear what a change in the state of the ground does.

Without JavaScript only one state is shown: rainfall of 40 u. on each section. Other values require JavaScript to be enabled.

0–100 u. (arbitrary units, not millimetres). Total for the valley: 3 × 40 = 120 u.

Runs off at the end of the valley (section C):

  • dry ground 50 u.
  • saturated ground 86 u.
  • frozen ground 101 u.

stays

Soil, turf and small hollows hold water in place. The sum for sections A, B and C. We do not model time, so we do not know what happens to this water later.

  • Dry ground24 u.
  • Saturated ground6 u.
  • Frozen ground9 u.

soaks in

Fissures and pores in the limestone take water down into the rock. The sum for the three sections. The model does not know the further path of this water and does not assign it to any route in Wodąca Valley.

  • Dry ground46 u.
  • Saturated ground28 u.
  • Frozen ground10 u.

runs off

The rest flows down along the floor. The number is the runoff leaving the lower end of the model valley (section C), including water carried in from A and B.

  • Dry ground50 u.
  • Saturated ground86 u.
  • Frozen ground101 u.

All nine bars share one scale: full width = 300 u. (the largest possible total rainfall, 3 × 100). A small number gives a thin bar; zero gives no bar.

Where along the way water flows over the surface (in the model)

The same rainfall, three sections from the top to the bottom of the valley. The thickness of the blue line grows with the volume of runoff leaving the section, on the same scale as the bars above (full scale is 300 u.; values above it are cut off at its end). A dashed line and “0 u.” mean that in the model nothing flows out of the section.

Cross-section diagram: sections A, B and C Our own diagram. The surface of the floor slopes gently from left to right through three sections, A, B and C. Beneath section B three fissures run through the rock. This illustrates a principle; it is not a profile of a real valley. ABC

A upper floor: soil and turf

B fractured limestone, swallow-hole zone (fissures beneath)

C lower floor, outlet of the model valley

Dry ground

20 u.from A
30 u.from B
50 u.from C

Runoff passes through A, B and C.

Saturated ground

30 u.from A
54 u.from B
86 u.from C

Runoff passes through A, B and C.

Frozen ground

34 u.from A
67 u.from B
101 u.from C

Runoff passes through A, B and C.

Try setting the rainfall to 23: on dry ground runoff appears in A, vanishes in B, and in C only the runoff from its own rainfall is left.

Balance check

Nothing is lost and nothing is created: stays + soaks in + runs off = total rainfall.

  • Dry ground: 24 + 46 + 50 = 120 u.
  • Saturated ground: 6 + 28 + 86 = 120 u.
  • Frozen ground: 9 + 10 + 101 = 120 u.
Model parameters (arbitrary, not measurements)
  • Dry ground: A holds up to 8 and absorbs up to 12 · B up to 6 and 24 · C up to 10 and 10.
  • Saturated ground: A up to 2 and 8 · B up to 1 and 15 · C up to 3 and 5.
  • Frozen ground: A up to 3 and 3 · B up to 2 and 5 · C up to 4 and 2.
  • The values were chosen to show the principle: the fractured section B has the greatest absorption capacity, and saturation and frozen ground reduce it. They do not come from any station or from studies of Wodąca Valley.

Limits of knowledge

What the sources tell us, and what is missing here

According to the sources (carried over from V2, not re-checked in V3)

Unknown, missing, not decided here

  • Where the swallow holes in Wodąca Valley are, and where the underground path of the water leads.
  • How much rain it takes for a watercourse to appear in this valley. The numbers in the model do not determine this.
  • Whether the five traces described occur in this valley, and how to interpret them at a specific spot. A geologist should confirm that interpretation.
  • Whether water is flowing there today. This page is not a forecast, a warning or permission to enter the terrain.
  • What the valley looks like while it carries water. No photograph of such an episode was supplied.

Do not enter channels, hollows or openings during downpours or after them. The diagram says nothing about the safety of the terrain.

Assumptions · sources · changes from V2

Sources and model assumptions

Model assumptions

  • A single balance step, without time: no hydrograph, evaporation or delay.
  • The same rainfall W falls on each section. B receives W plus the runoff from A; C receives W plus the runoff from B.
  • A section first holds water (up to its retention capacity), then absorbs it (up to its absorption capacity), and passes the rest on.
  • “u.” is an arbitrary unit, not a millimetre or a litre. The capacities of the sections are for teaching purposes.
  • Water that has soaked in does not return anywhere in the model and has no further route.
  • The results are not a forecast, and the diagram does not show the profile of any real valley.

Sources and materials

External references are ordinary links; the page does not load any resources from them. The content from the sources was carried over from V2 and not reopened in V3, so it does not have the status “checked”.

What was removed from V2 and why
  • Photograph loaded from the internet: replaced with our own drawing, because the page is meant to work offline. The photograph remains as a link.
  • Walker’s notebook saved in the browser: removed. It was not needed to understand the topic. V3 saves nothing; old notes under the key atlas-v2-114 may remain in the browser, but this page does not read them.
  • Checklist with an automatic “diagnosis”: replaced with five traces, each described with what does not follow from it. A combination of ticks should not pretend to be an identification.
  • “Continuous watercourse” banner with icons: replaced with a neutral reading of the model in rows A–B–C, without judging the real valley.
  • Choosing a sector with one button: the description of the sections is always visible next to the diagram.
  • Comparison with the V1 model (a single reservoir): this is a story about versions of the page, not about the valley. Its point, that averaging loses the vanishing of a watercourse, is shown by the example with rainfall 23.
  • Kept: the three states of the ground, the A, B, C cascade with the total of water conserved, the 0–100 u. slider and the button that restores the starting value. The slider is now in the second layer, after the story of the place.