The time frames on the topic:
Hydraulic engineering techniques
When the Dutch colonists began cultivating the Sietland east of Stade in the early 12th century, they already had excellent knowledge of hydraulic engineering. They had knowledge that had already been developed in Flanders hundred years ago.
Almost all the time frames of the Hollerweg have overlapping topics. However, they are always assigned to only one topic. The topic, which becomes more vivid at this point, than elsewhere.
Time frames on hydraulic engineering: