Model cross-section · conventional units (c.u.)

How the Milicz Ponds are filled

Three periods, three steps of the cascade. Choose one inflow or outflow and set it separately in each period; the cross-section shows where the water stays and where it evaporates or flows out.

Which inflow or outflow should be followed through the season?

Supply from the canal:

custom

Period 1 Period 2 Period 3

Period 1

Spring

March–April · supply 160 c.u.
Start of the season: filling after winter.

A 58% · B 58% · C 75%

Monk A→B 40%

A28.8 / 50 c.u. · 58%evaporation −2.0 c.u.

↘ B 84.2overflow 65.0 · monk 19.2

B58.2 / 100 c.u. · 58%evaporation −3.0 c.u.

↘ C 63.0overflow 24.2 · monk 38.8

C149.9 / 200 c.u. · 75%evaporation −3.1 c.u.

→ out of cascade 0.0overflow 0.0 · monk 0.0

conventional threshold ≥65% — ✓ met

retention 145.0 + intake 100.0 − evaporation 8.1 − outflow 0.0 = 236.9 c.u. · closure: difference 0.0

Period 2

Summer

May–August · supply 70 c.u.
In the model: smaller supply, strongest evaporation.

A 62% · B 66% · C 78%

Monk A→B 30%

A30.8 / 50 c.u. · 62%evaporation −6.0 c.u.

↘ B 32.0overflow 18.8 · monk 13.2

conventional threshold ≥40% — ✓ met

B66.4 / 100 c.u. · 66%evaporation −7.2 c.u.

↘ C 16.6overflow 0.0 · monk 16.6

C156.5 / 200 c.u. · 78%evaporation −10.0 c.u.

→ out of cascade 0.0overflow 0.0 · monk 0.0

conventional threshold ≥60% — ✓ met

retention 236.9 + intake 40.0 − evaporation 23.2 − outflow 0.0 = 253.7 c.u. · closure: difference 0.0

Period 3

Autumn

September–November · supply 50 c.u.
In the model: inlet closed, levels lowered through the monks.

A 18% · B 21% · C 19%

Monk A→B 70%

A8.8 / 50 c.u. · 18%evaporation −1.5 c.u.

↘ B 20.5overflow 0.0 · monk 20.5

conventional threshold ≤30% — ✓ met

B20.8 / 100 c.u. · 21%evaporation −3.5 c.u.

↘ C 62.6overflow 0.0 · monk 62.6

conventional threshold ≤30% — ✓ met

C38.8 / 200 c.u. · 19%evaporation −6.0 c.u.

→ out of cascade 174.3overflow 19.1 · monk 155.2

conventional threshold ≤30% — ✓ met

retention 253.7 + intake 0.0 − evaporation 11.0 − outflow 174.3 = 68.4 c.u. · closure: difference 0.0

Balance ledger

Initial level + intake from the canal = final level + evaporation + outflow from the cascade. The transfers A→B and B→C are internal: the upper pond loses what the lower one gains. Values are in c.u., rounded to 0.1; the calculation is done in tenths, so the totals agree to the last digit.

Balance now
Period	Intake from canal	Final level A · B · C	Evaporation	Passed A→B	Passed B→C	Outflow from cascade	Retention
1. Spring	100.0from supply of 160 · 60.0 stays in the canal	28.8 · 58.2 · 149.958% · 58% · 75%	8.1	84.2overflow 65.0 + monk 19.2	63.0overflow 24.2 + monk 38.8	0.0overflow C 0.0 + monk C 0.0	145.0 → 236.9
2. Summer	40.0from supply of 70 · 30.0 stays in the canal	30.8 · 66.4 · 156.562% · 66% · 78%	23.2	32.0overflow 18.8 + monk 13.2	16.6overflow 0.0 + monk 16.6	0.0overflow C 0.0 + monk C 0.0	236.9 → 253.7
3. Autumn	0.0from supply of 50 · 50.0 stays in the canal	8.8 · 20.8 · 38.818% · 21% · 19%	11.0	20.5overflow 0.0 + monk 20.5	62.6overflow 0.0 + monk 62.6	174.3overflow C 19.1 + monk C 155.2	253.7 → 68.4
Season	140.0from supply of 280 · 140.0 stays in the canal	8.8 · 20.8 · 38.818% · 21% · 19%	42.3	136.7overflow 83.8 + monk 52.9	142.2overflow 24.2 + monk 118.0	174.3overflow C 19.1 + monk C 155.2	145.0 → 68.4

Change relative to the saved “before” (now − “before”)
Period	Δ level A	Δ level B	Δ level C	Δ evaporation	Δ overflows (A, B, C)	Δ outflow from cascade	Δ final retention

Model assumptions

Everything the calculation takes as given. Changing any assumption will change the result.

Conventional units. 1 c.u. is a conventional portion of volume, with no conversion to m³. Capacities: A 50, B 100, C 200 c.u. Initial levels: 15, 40, 90 c.u. (an assumption carried over from V2).
Layout. Canal → sluice gate → pond A → monk A → pond B → monk B → pond C → monk C → outflow beyond the cascade. Only A has an inlet from the canal.
Order within a period. The ponds are calculated in the order A, B, C. In each pond: (1) inflow from the canal or from the pond above; (2) anything above capacity overflows downstream (from C: out of the cascade); (3) evaporation, i.e. a fixed percentage of the level after the overflow; (4) the monk passes the set percentage of the remainder downstream (from C: out of the cascade).
Time. Within a period, flows are instantaneous. The discharge from A reaches B before B’s overflow and evaporation. A different order of operations would give a different result; the model does not describe flow time.
Closed inflow. Inlet 0 or monk 0%: the balance still closes, and the total falls only through evaporation and outflow from C. Internal transfers reduce the upper pond and increase the lower one by the same amount.
Supply. Intake does not exceed the supply for the period. Water not taken stays in the canal, outside the cascade balance.
Evaporation. Conventional coefficients per period and pond (scenario A, spring / summer / autumn: A 4 / 12 / 5%, B 3 / 8 / 4%, C 2 / 6 / 3%; scenario B has higher ones). These are assumptions, not measurements.
Drawing. The water level in the cross-section is drawn in proportion to volume, as if the basin had constant slopes. This is a simplification of the drawing, not a depth measurement. The slopes and depths are invented.
Thresholds. The “conventional threshold” (C ≥65% in spring; A ≥40% and C ≥60% in summer; ≤30% in autumn) is a teaching threshold, calculated from the rounded percentage. It is not a recommendation for pond management and requires consultation with specialists.
Geometry. The drawing does not reproduce any complex of the Milicz Ponds; we have no data from the manager. A correct balance does not mean a good outcome for fish, birds or water quality.

The real ponds: what the sources say

Statements carried over from the V2 descriptions. The sources were not opened in this run; each needs to be checked at its address.

According to description [1] · to be verifiedThe development of pond management included building up dykes, reinforcing banks and digging ditches to bring water in and carry it away.

According to educational material [2] · to be verifiedThe Milicz Ponds nature reserve was established in 1963 and comprises five separate complexes; the stated area is 5,324.31 ha, and more than 130 breeding bird species have been recorded, 60 of them waterbirds and wetland birds.

According to educational material [2] · to be verifiedThe difference is described between shallow fry ponds and large rearing ponds at Ruda Sułowska. So there is no single water level for the whole area — and that is why A, B and C in the model have different capacities.

According to the manager’s website [3] · to be verifiedThe Milicz Ponds still carry on fish farming and education about its traditions.

No document: a photograph of a dyke and a monk

There is no photograph of a real dyke or monk here, because we have no material with confirmed rights. The cross-section and the monk symbol are our own schematic, not a historical document and not a construction drawing.

V2 pointed to a photograph from Wikimedia Commons (Stawno complex, author: Strumyczek, CC BY-SA 4.0 — according to V2, not verified here), described as a water surface with a dyke; it does not document a monk. What remains is a link to the file page [4], without embedding.

Sources for further verification

[1] Stawy Milickie — historia i tradycja [Milicz Ponds — history and tradition]: dykes, ditches bringing water in and carrying it away.
[2] DZPK — ścieżka przyrodnicza „Ruda Sułowska” [DZPK — “Ruda Sułowska” nature trail]: nature reserve, birds, types of ponds.
[3] Stawy Milickie SA: fish farming and education.
[4] Wikimedia Commons — Stawy_Milickie05.jpg: file page (author, licence); not embedded.

Limits. This is a teaching model of a volume balance, not a manual for operating ponds or a reading from the reserve. The calendar of periods is conventional.