Week 3 - Rivers - Ryan Klassy

Mekong river - Source: Wikipedia user Shanon1

Note: For the purposes of this blog I will include the Lancang River as part of the Mekong. The reason I do this is because geologically they are the same stream of water all feeding from the same drainage basins. To me, a name is just a name, but the river is what it is regardless of what you call it. Click on photos to enlarge them.

This week I chose to visit the Mekong River in Southeast Asia. I chose this destination because the river is not only very long, but it also showed many different geological features that I learned about during the readings in chapter 13 along with the videos.

Many rivers around the globe (as I look at Google Earth) seem to have a more simple dendritic drainage pattern. Dendritic patterns (called this because they resemble a deciduous tree) were apparent in most of the rivers I found. The Mekong has some dendritic drainage patterns but also has a complex pattern of other types such as steep radial patterns from high up in the mountains of Tibet.

Meandering - Source: Google Maps

Many rivers around the world show what is called a meandering flow pattern. Meandering is when the river winds back and forth across the landscape. This meandering flow causes irregularities in the velocity of the water. Points that are on the inner edge of a curve tend to slow down, while points on the outer edge must speed up to cover the extra distance. The slower water loses energy, dropping more sediment to create point bars while the high-energy outer edge carves a cut break into the other side.

Dam in river - Source: Google Maps

To the right you can see that I was able to find a dam! I was not expecting this and didn't even search for it. I was just scrolling up the river (um... eh hem... I mean I was driving up the river in my car!) when I saw this dam! Dams are a very important renewable source of energy taken from the flow of the water, but this energy comes at a price. Dams affect the river's ability to naturally flood, and also change the base level which changes the flow rate on the upper end. Dam failures can also be catastrophically deadly events.

Heavy braided channels - Source: Google Maps

This screenshot on the left shows an excellent example of some of the river's braided channels. Braided channels such as this one likely formed due to a larger base sediment (such as gravel) along with a changing flood level which, when it dries back up, forces the streams to become temporarily isolated before rejoining later on. I was very excited to find such a large area with so many braids in it! You can see that at the upper end the braids are larger and farther apart, then as the flow downwards they become more narrow and closer together, eventually rejoining at the end. Can you see examples of meandering within the braids? :)

Gullies - Source: Google Maps

In this screenshot to the right you can see another way that rain water is able to find it's way into the river. As rain falls on the upper parts of the ridges they divide to each side depending on gravity. As they flow down they will make their way into rills and gullies. Rills are the smaller cracks that have a slightly dendritic appearance to them. The rills then flow into the gullies which you can clearly see in this photo. I drew an arrow on one of them to show what I am referring to, but as you look around the screenshot you can see many others.


Well, I must say I thought this lesson on rivers was going to be quite dry (pun intended), but it turned out to be more juicy than I thought! I didn't realize that there were so many things to learn about running waters. I never knew about the causes and effects of meandering. Now when I go to a river I am going to be looking for these things and will have a whole new appreciation for what I see! (Just like when my wife and I go for a walk around the neighborhood and I am pointing out rock types :)

Why didn’t the hipster swim in the river?  It was too mainstream. 😂😂😂