Right now I'm trying to build a colonial setting for an RPG, in which a group of farmers accidentally uncovers some ruins of great power buried under a swamp while draining it. Before the swamp is completely drained, I'm also planning some kind of conflict as the indigenes (who are aware of what lies beneath the swamp) attempt to stop the swamp from being drained and the ruins from being revealed.

The problem is that I haven't the faintest clue how people actually drain swamps. Google isn't much help here, either: most of the results deal with the ecological consequences of making swamps disappear.

How did people go about draining swamps three hundred years ago? What kind of technology was necessary? Was it a one-person job, or did it take teams of coordinated laborers? Did they use dams to keep water from coming in, or ditches to keep water from going out?

And when they finally succeeded, what was the result? Simply a lower water level? Very muddy (but still usable) land? Dry land?

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    $\begingroup$ As written, this question seems better suited for History.SE $\endgroup$ – Travis Christian Jun 15 '16 at 14:24
  • $\begingroup$ @TravisChristian Could I make this better by specifying that I'm mostly curious about how somebody could disrupt the process? (Because then it's more about plot and less about mere historical curiosity.) $\endgroup$ – HardlyKnowEm Jun 15 '16 at 14:37
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    $\begingroup$ This does seem to relate more to engineering than worldbuilding ... Google how the Dutch did it. I'm sure there's some papers discussing it, and that might give you a better idea of what further questions to ask. $\endgroup$ – AndreiROM Jun 15 '16 at 14:39

Swamps form in areas of low topographical relief (ie. little overall change in elevation and relatively level).

Water enters this area (possibly from a nearby river, or springs, or runoff) and the flow of water through a wetland (swamps are defined as forested wetlands) is quite slow over the mostly flat land. There are generally some faster moving channels through the area, but most water is slow moving or even stagnant.

Draining a swamp is a simple matter (though not necessarily trivial). Additional drainage needs to be provided to the area so that the water drains away faster than it is replenished. A system of canals and ditches can rapidly dry out wetlands. As a caution, if these canals drain into the ocean, rising tides can actually send salt water up the canal to turn the area brackish.

Alternately, if you set up levees to block outflow, a wetland can be transformed into a shallow lake.

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Michael Richardson already answered for the situation where water can be drained naturally. However there are many situations where this was not the case. The next step is active draining. End result is dry land always: Arable land is the very reason for the large effort it requires.

Typically what the job gets done is:

  1. Build dams around the projected 'polder'
  2. Dig draining canals inside
  3. Build windmills on top of the dams
  4. Apply the windmills to remove the water
  5. [In case of seawater] After the water is drained, plant salt tolerant crop for the first few seasons

It takes a long time to do in any case. Slowing or blocking progress is easy: Damage the dams, burn the mills. To get really nasty: Attack the workforce.


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  • $\begingroup$ Excellent point about low-lying areas with no real outflow. Also, if the swamp is large enough, it would take prohibitive resources to build enough canals to make an impact. $\endgroup$ – Michael Richardson Jun 17 '16 at 5:01

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