Recently in travelling back to New England I discovered ditches in the lowlands/wetlands of the shoreline on Google Maps satellite view. They are clearly man-made, but even with all the agriculture and fishing in the area, I cannot figure out the purpose of these. I have discovered that they seem to be all over New England, but sometimes it's not a.

What is the purpose of the man-made lines that appear in all these satellite images?

An example image is below, but it is not very high resolution. Here are some links that show the phenomenon:

Great Island near Old Lyme, CT

Near Stonington, CT

Marsh near Narraganset, RI

Goose Island near Old Saybrook, CT (maps view, not satellite, helps make the lines clear)

Near Marion, MA

Great Island near Old Lyme CT


they are drainage ditches intended to drain salt marshes.

They may be old and no longer maintained, it is impossible to tell for certain from satellite but it seems likely.


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  • $\begingroup$ Thank you. Why would this be done? Wouldn't the ditches increase erosion but still leave the marsh too wet to be used for anything? $\endgroup$ – pbarranis Aug 17 at 18:14
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    $\begingroup$ they are done to drain the marsh, usually to help dry the land around them, or for use in building. marshland stays wet becasue it is so flat water does not move much. $\endgroup$ – John Aug 17 at 18:47
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    $\begingroup$ drainage ditches are used to dry up fields that are too wet for growing foodcrops too so it makes farming possible where the ground was originally too wet,so ditches are used way inland too but sadly this increases the amount of CO2 released from the ground,areas with permafrost is a good example of this(removing the water makes organic matter decompose at a faster rate). $\endgroup$ – trond hansen Aug 18 at 5:14

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