Properly mapping dry washes

This might be a good example where the wadi is directly adjacent to an erg: Way: 46227123 | OpenStreetMap

It may be an issue with my layering. But when I do a test at that area the wadi and the sand are almost identical so I am not uploading an image at this time. I have a few other things I must attend to but I will try to get back to adjusting the sand and/or wadi pattern(s) to make the difference more visible.

1 Like

I am proving to myself that I am not a professional cartographer nor a graphic designer. :slight_smile:

It turns out that your linked polygon overlaps with the sand polygon so one shows through the other which makes things blend a bit. Anyway, my failings as a visual designer shouldn’t stop someone else who knows what they are doing come up with a good rendering.

In the meantime, here is what I have after several iterations. I abandoned the greener color because if I made it contrast enough with the sand then it looked like a more heavily vegetated area than I wanted. In the image the darker shade is the wadi and the lighter is sand. Background is white where there is no landcover specified.

3 Likes

I think that works. I think that area needs to be edited so that the two polygons don’t overlap, but it’s nice to see that the rendering can work if they do.

Wondering if using something similar to the current intermittent water scheme (blue lines) but changing the lines to grey / brown & reducing their number to half / quarter to make it less dense would work?

Something like:

& you may be able to tell that I’m a mapper, not an artist! :crazy_face: :roll_eyes:

2 Likes

Namibia for the win! Tsondab Vlei where I made some edits, added streams off the main channel and ended the wadi area when the waterway constricted down to a width represented by just a line.

1 Like

Had a thought & looked at the legend on some Australian Government supplied maps:

Then when you zoom in on lakes & waterways, including dry / intermittent, you get:


“Mainly dry”, with a smattering of red-brown dots. That could also work.

7 Likes

I like their rendering of intermittent and “mainly dry” for lakes and think it could also work where water sometimes flows.

2 Likes

There’s some pretty consistent rendering of wadis. The historical USGS topo style above covers the area of the feature with reddish brown dots.

The current style used in the USGS National Map uses a light brownish gray dot pattern with a darker brownish gray dashed border:

Screenshot 2024-02-20 at 10.53.38 AM

Personally, I like the dashed border because wadis often have well-defined banks and the border makes them stand out. The banks are important aspects to map because they’re often steep and sometimes vertical, so they can be barriers to travel.

But I think any rendering within the range of styles we have here would be good.

4 Likes

Is there something more we need to do before documenting this on the wiki?

I was wondering about that too.

It seems to me that the discussion here, along with the images that have been posted in this thread, would be pretty good content for a proposal page on the wiki.

3 Likes