Making Fancier Rivers

Today, we will discuss how to make rivers that have their own special features and quirks without being a horrid mess.

While you might not emerge as Leonardo Di Maprio, Award Winner for Mapping, or go down with the names of river explorers such as Schoolcraft, that doesn't give you an excuse for bad rivers.

This will be divided into three main parts; River Bending, River Splitting/Merging, and other miscellaneous quirks of rivers and interesting things they can do.

I will also include footnotes for further reading and sources. These will be included on the bottom of the post.

River Bending

Rivers bend. A perfect river is straight and goes directly from source to end, but no river is perfect. As long as a river exists, animals will live in it or near it. Animals like beavers may dig burrows in the banks of a river, which will weaken it. As water flows, it will tear at the bank, weakening it where things like burrows are. This will cause one side of the bank to erode, slowly making a river go from a perfect straight | to a more bended thing. This means water will flow more towards the bend and the current need the other side of the bank will weaken, causing silt to build up since the current isn't strong enough to carry it. This builds up the bank, helping ensure the bend is the only route possible.

As this happens, the flow will force the silt in the water to crash against the other side of the river bank, making it bend, and so on. The water will then ricochet off this, causing it to crash into the other bank. This makes more curving happen.

This is how river bending happens. For a video with visuals and further explanation, refer to the citation.^[1]

River Merging & River Splitting

So, you have a nice continent and want interesting and visually pleasing rivers. So, what do you do? You decide to make rivers split to add some pleasing cosmetics.

But hold up! You just violated an important rule. Unless you're making the Mississpliti, rivers don't often split.

The reason why is simple; water takes the most direct route towards its end. If its origin is up a mountain, it will flow downwards by the easiest path possible.

This means rivers will seldom split. Instead, they often merge, such as with the Missouri and the Mississipi.

Since water likes to take the most direct route, it will often go to the nearest way for it to escape. For the Missouri River, which flows east and south, the fastest way to the ocean is to flow into the Mississipi. Most that seem to split will actually be merging.

This does not mean it's impossible or without exception, however.

River Bifurcation^[2] is when a single river splits into two different streams, referred to as a distributary. The largest natural example is the Casiquiare Canal^[3] in South America.

Another common example you might know are river deltas. These are examples of bifurcation.

Do note, however, that deltas occur close to the shore, not half way up the river's length.

Miscellanous River Features

Now, we will discuss odd quirks of rivers that you can use to make interesting rivers!

Oxbow Lakes

Oxbow Lakes^[1][4][5] are leftover remnants of river bends that have long since been cut off from the main river. As river curving becomes more extreme, curves will eventually meet, making a more direct route that water will take. This means that silt will build up and remake a bank, leaving behind Oxbow Lakes.^[1][5]

As oxbow lakes have no input or output for water, they often either dry up from evaporation or survive from rainfall.^[5] Oxbow lakes are usually on low plains, so if the land tilts downwards towards the Oxbow, rainfall will feed it.^[5]

River Islands

River Islands^[6] are islands found in the middle of a river, splitting the river in two on the sides of it. These can be used as something to break up the monotony of a river without adding splits and insane curves.

Further Reading & Citations

• 1 (Youtube) MinuteEarth — Why Do Rivers a Curve?

• 2 (Wikipedia) River Bifurcation

• 3 (Wikipedia) Casiquiare Canal

• 4 (Wikipedia) Oxbow Lake

• 5 (National Geographic) Oxbow Lake

• 6 (Wikipedia) River Island