What creates these parallel grooves?

Here's two examples: 
goo.gl/maps/irQcNwtKNSiJs4FP6
goo.gl/maps/cwmMEcoq63udion57

It's all along the East coast of USA... I figure it's something simple.

These are tributaries.

According to Wikipedia  A tributary is a stream or river that flows into a larger stream or main stem (or parent) river or a lake A tributary does not flow directly into a sea or ocean.

Tributaries and the main stem river drain the surrounding drainage basin of its surface water and groundwater, leading the water out into an ocean.



A confluence, where two or more bodies of water meet together, usually refers to the joining of tributaries.

these are obviously artificial channels of a huge drainage system.

I think it is some kind of land- or tidal-management.
this way they can keep tidal water flows regulated and get bends of "dryer" land in the coastal zone that they can keep much more under control this way.


compare how great is the difference if you check visible hidrological features at nearby sites, where channel system had not been developed (at the right of the screenshot below):

example GE view at >>39.424007, -74.460896<<



only a guess... ...and another thread I bookmark. (:

best!
g

Wetland drainage, I think. In some cases could it be channels for the annually reed harvest. I know similar locations at the Lake Neusiedl (Austria). See eample.

Attachments:

Reed.kmz (680 B)

Great answers guys, thank you. Sorry for delayed reply.

Yes, drainage, erosion control.. something like that probably.  

It is worth comparing these lines to very similar ones in Florida, which are the remains of old rice paddies (apparently).



It's interesting that the lines still look pretty well-defined, even after 150+ years.
Many other lines in the general area look similar, if you surf around the florida rivers and coasts.

goo.gl/maps/eRFW9qwJkZcUyJzi9
www.moderncities.com/article/2018-may-exploring-white-oak-conservation

So is it rice paddies, or coastal management? Or both/either depending on the location?