Essential river guidelines for mapping

[waldronate]

Lakes with no outflow are salty. If the only way for water to leave a lake is through evaporation, the lake will tend to accumulate salt and other minerals carried by the water. The longer the lake goes with no outflow, the saltier it will get. These kinds of lakes and seas often form below sea level. Erosion will generally create an outflow eventually in a lake above sea level.

The parts about sea level in relation to salty lakes aren't generally true. Basins with internal drainage (lakes or salt pans with no outflow) are characteristic of arid regions and don't have any relation to sea level.
Virtually all of the salt lakes/playas (dried up salt lakes) in the Western US are well above sea level, for example, as are those in the Taklimakan and Alptiplano deserts in China and South America. Some of the more well-known examples of salt lakes such as the Dead Sea and Salton Sea are below sea level, but that's just coincidence. If you're a basin below sea level that's not full of water then it's because you're having internal drainage, not because you're below sea level.

[RobA]

The parts about sea level in relation to salty lakes aren't generally true. Basins with internal drainage (lakes or salt pans with no outflow) are characteristic of arid regions and don't have any relation to sea level.
Virtually all of the salt lakes/playas (dried up salt lakes) in the Western US are well above sea level, for example, as are those in the Taklimakan and Alptiplano deserts in China and South America. Some of the more well-known examples of salt lakes such as the Dead Sea and Salton Sea are below sea level, but that's just coincidence. If you're a basin below sea level that's not full of water then it's because you're having internal drainage, not because you're below sea level.

The real trick is for this to happen the water has to evaporate, not seep into the earth. If the ground is porous, the water (minerals and all) will just drain away. It is only when the ground is non-porous, or when it evaporates faster than it seeps that the minerals build up and forms salt pan or salt flat.

-Rob A>

[Midgardsormr]

Thanks for the correction, Joe. I'll amend my original post to remove the misinformation. I found that discussion I remembered about delta formation, but you just described it much more elegantly, so I'll just post a link to that thread: A brief discussion of Marshland and river deltas.