March Entry: River Basics

Hello folks,

Not sure if I'll be able to get a decent entry in this month, but I'll throw my hat into the ring.

First things first: a little inspiration from the real world:

http://roger.carbol.com/1Mhp/images/newfoundland.gif

(Just to be clear -- I did not create the above map in any meaningful way. It's all the work of Mother Nature.)



Cheers,
Roger

Now that's quite a gauntlet to throw down. Welcome to the guild.

Labrador?

-Rob A>

Thanks! I've been a fan of the Guild for ages.

Here's another real-world island, with some topo, that might be more immediately helpful (for me, anyway.)

http://roger.carbol.com/1Mhp/images/flores_island.gif

If I take a closer look, a number of useful points are illustrated:

http://roger.carbol.com/1Mhp/images/flores_close.gif

• The way the lakes are nestled in to the contour lines. They're local minima of elevation, to lapse into mathematical jargon. (Well, almost. If they were true local minima, they wouldn't have any discharge river.)
• It's easy to see that the rivers cross the contour lines at right angles. They follow the gradient, to again bring out the jargon.
• The deformation of the contour lines near the rivers that reflect the river valleys (technically, the slightly-dirty-sounding 'invagination'.)
• The way the ridge-lines function as watersheds.
• Chain lakes.
• The rivers running through steeper terrain (where the contour lines are closer together) are straighter, in general, than those in the flatter terrain.

I feel like I'm learning a lot already.


Cheers,
Roger

The first map is of Newfoundland, yes. Labrador is the part of the province that's on the mainland.

The second (and third) maps are of Flores Island, which is off the west coast of Canada.


Cheers,
Roger

Now that is useful.

I guess the base of the lakes must be true local minima, otherwise there would be no collection of water. At the very least there's going to have to be a point of inflection.

Thanks Roger, that is very instructive.

Hi Roger, When you do post a WIP of the rivers can you use the manage attachments and upload it then it will get included in the challenge thumbnails which is the sticky thread at top of current challenge.

Yep; I can do that. I'll have a 'real' WIP image ready... someday... I hope.


Cheers,
Roger