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TOPIC: Shorelines using the National Hydrography Dataset

Shorelines using the National Hydrography Dataset 6 years 2 months ago #5862

  • foo_g
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Is it possible to use this to download creek or river channel paths?
I've got a lake that, when I zoom in on it, isn't visible outside of an aerial photo. (DMS: 40° 41' 10.297" N, 91° 59' 42.315" W)

There are just so many download and file options here that it's kind of a needle in a haystack situation for a novice like myself.
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Shorelines using the National Hydrography Dataset 6 years 2 months ago #5869

  • foo_g
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I uploaded a boundary for another lake and the shoreline file also included boundaries a lot of little nearby ponds.
Figuring out which one to keep and which 159 to delete was a bit of a time eater.
Is there a quick way to identify which boundary is which when you have multiples?
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Shorelines using the National Hydrography Dataset 6 years 2 months ago #5870

  • Matt
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Probably the easiest way is to load your downloaded Shapefile into QGis and then select the shoreline(s) you want. You can then save them again in a file with only those. It can also be useful if you need to modify very large polygons (e.g. a river outline) - then you can cut it to the size you need in ReefMaster and re-save it.
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Shorelines using the National Hydrography Dataset 5 years 3 months ago #7490

  • ndoggac
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This data can also be found on the USDA Geospatial Gateway. Pick your state and county of interest, then download the 12-digit watershed boundary data set under the "Hydrologic Units" section. It's by county though, so other bodies of water are included as well. Besides having multiple bodies of water in the same file, an additional issue I ran into was the data for my lake had both shoreline boundary and island data in one file. This confused RM and the results were messed up.

To get around this, I loaded the shapefile in QGIS, exported to KML, opened the KML in Google Earth and zoomed into the body of water of interest. I right clicked on the shoreline boundary and selected properties. The associated entry (out of hundreds in that county's folder entry) is then highlighted in the left menu. I then closed the properties window, right clicked on the highlighted entry in the left menu and selected "Save As" and saved to KML.

Using notepad++, I then edited the KML directly. The longest set of points was the boundary, which I copied to a separate polygon KML file. Then I took all the island boundaries and combined them into another separate "folder of polygons" KML file. I had to edit the KML code a bit, as the islands were originally designated as "inner boundaries", and they had to be changed to polygons. I used the "Search" and "Replace All" functions in notepad++ to do this fairly easily.

Then in RM, load the boundary file first, go back into the edit menu, and set it to "boundary", then import the islands file. My island file was 97 boundaries, and RM took about 15 seconds to load them all. The default setting is "island" in RM, so I didn't have to make any further changes under the "Edit" menu.
Last Edit: 5 years 3 months ago by ndoggac. Reason: Added USDA subcategory and file information
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Shorelines using the National Hydrography Dataset 3 years 5 months ago #10271

  • MarsArtis
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What if we draw a map which an polyline that is not closed as shoreline? How to deal with it?
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Shorelines using the National Hydrography Dataset 3 years 5 months ago #10272

  • Matt
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ReefMaster will close it for you, which may or may not be what you want.
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Shorelines using the National Hydrography Dataset 3 years 2 months ago #10421

  • Norton79
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Hi matt
Have you found anything like this for Australia?
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Shorelines using the National Hydrography Dataset 3 years 2 months ago #10433

  • Meggs1
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@Norton79


This only works for Navico plotters (at5 files).

I have a Simrad plotter and use files from this site to give me an Aussie background map. It has some navigation aids (but NOT all) so would still need to refer to a more accurate source for navigation. It will not give you a "shoreline" as discussed above but I find it is enough for me.

wiki.openstreetmap.org/wiki/AT5-OpenSeaM...owrance_Simrad_B%26G
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Shorelines using the National Hydrography Dataset 8 months 2 weeks ago #11935

  • Igor Ivanov
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Australia map
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Shorelines using the National Hydrography Dataset 8 months 2 weeks ago #11936

  • Meggs1
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I finished up using Open Street/ Open Sea map in combination with a hand drawn coastline from Google Earth. I've only drawn the parts of the coast that are adjacent to the areas I map as the whole coast is over 4000 km long....
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Shorelines using the National Hydrography Dataset 8 months 2 weeks ago #11939

  • gpiverson
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Here's the wiki entry containing the links to the downloadable ocean files - wiki.openstreetmap.org/wiki/Coastline.

Explanations about geometric objects below are simplified to describe the spirit of the structures. OSM's data organization is contextual.

The IMC's ocean extract can be hit or miss for a couple reasons.
* When Geofabrik clips, they cull all polyline features by the poly file.
* In unusual cases, there isn't any shoreline in the file.

Ocean does not exist as a polygon within OSM. Ocean is generated by combining all the shoreline polylines. The IMC is capable of creating an ocean but only if a shoreline feature exists and the shoreline features is a closed polygon or extends all the way to the edge of the rectangular extents that are identified in the file. Even in cases where ocean is generated, areas outside the poly file may be misidentified due to shoreline exclusion. For these reasons, ocean generation is optional within the IMC.

Edit - OpenSeaMap also generates At5 files - wiki.openstreetmap.org/wiki/AT5-OpenSeaM...owrance_Simrad_B%26G
Last Edit: 8 months 2 weeks ago by gpiverson.
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Shorelines using the National Hydrography Dataset 8 months 1 week ago #11980

  • Igor Ivanov
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Are there any difficulties with the coastline?
Give the coordinates. Let's try to solve the problem.
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