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The influence of anthropopressure..

areas, as is exemplified by the adaptation of the Bogdanka river for the needs of water mills in Poznań (Kaniecki 1993).

Fig. 3. Location of water mills (1) and dikes (2) in the vicinity of Poznań in the 15th

and 16th centuries (Kaniecki 1993):

water mills: 1 — Bogdanka, 2 — Folusz, 3 — Folusik, 4 — Śluza, 5 — Piła, 6 — Podgórnik,

7 — Czapnicki, 8 — Wielki, 9 — Wierzbak, 10 — Ungrów, 11 — Górków, 12 — Tbpolny,

13 — Faffków (hospital św. Krzyża), 14 — hospotal św. Ducha, 15 — Przepadek,

16 — Kapitulny, 17 — Groffowy (Dominikański), 18 — Podolny, 19 — Środka, 20 — św. Jana, 21 — Łączny, 22 — Nadolnik, 23 — Garbuz, 24 — Szklany; dikes: a — Chwaliszewo, b — Nowa Grobla, c — Czartoria, d — Łacina, e — Kamienna, f — Spustna, g — near

Dominikanie, h — near mili Przepadek, i — near mili Podgórnik

In the second half of the 16th century, extensive river regulation works, covering longer river segments, were initiated. River-beds, often blocked with wood and boulders, dammed with dikes and weirs, separated into arms and branches. The Warta and the Noteć rivers in their lower courses created a real water labyrinth covering the entire proglacial stream valley. Only short segments of their main beds were clearly marked. In spring, during thaws and after torrential rains, huge marginal lakes covering vast areas of land formed. The process was facilitated by a very Iow