<p>The island morphology isn't necessarily an indication of the river's depth because the river can be bimodal, with shallows and deeply incised trenches. One thinks of the River Congo which has many islands, but depths of up to 220 metres in its main incised channel. That said, however, if the river has a multi-channel, heavily braided morphology, as in the Waimakariri in New Zealand, or the Brahmaputra in Assam, then one can be fairly certain that the intense sediment load would have filled in any deep pools (excluding local scour in sharp bends, caused by super-elevated flow). In such cases, one may assume a shallow river profile, governed only by storm-flow peak stages. 
Where there are few or no islands coupled with geomorphologic indications of rapid cut back or rejuvenation, such as the Mekong upstream of its delta, then one may suspect very deep channel profiles. In general though, islands and bank morphology are not reliable indicators of a river's cross section. </p>

CC BY-SA 3.0
2016-12-29T02:08:47.533Z
2016-12-29T20:24:36.140Z
2016-12-29T20:24:36.140Z
Gordon Stanger
<p>Look at the photo below. Presumably, the river bed is a smooth shape. Therefore, it should be possible to infer the depth of the water from the photo, right?</p>

<p>I am not even an amateur of geo-science. </p>

<p>I am willing to listen to the experts. </p>

<p><a href="https://i.sstatic.net/h3CCn.jpg"><img src="https://i.sstatic.net/h3CCn.jpg" alt="enter image description here"></a></p>

CC BY-SA 3.0
2016-12-28T01:37:58.293Z
The barren fringe around those islands makes me think that's a reservoir whose water level has dropped.  It's impossible to tell anything without an idea of where it is.
Spencer
CC BY-SA 3.0
2016-12-29T05:50:38.830Z
Flow speed can be a function of depth after which you can consider sedimentology to get an idea of grain size . This  will determine the extent of deposition which decides shape of islands . More : Hjulström curve
shrey
<geology><geography><rivers><geomorphology><bathymetry>
Is it possible to infer the depth of a river from the shapes of the islands and the banks?
John
# Is it possible to infer the depth of a river from the shapes of the islands and the banks?

(Asked by: username_0 on 2016-12-27)

Look at the photo below. Presumably, the river bed is a smooth shape. Therefore, it should be possible to infer the depth of the water from the photo, right?

I am not even an amateur of geo-science.

I am willing to listen to the experts.

[![enter image description here](https://i.sstatic.net/h3CCn.jpg)](https://i.sstatic.net/h3CCn.jpg)

**Tags:** geology, geography, rivers, geomorphology, bathymetry

> **Comments:**
> **username_1**: The barren fringe around those islands makes me think that's a reservoir whose water level has dropped.  It's impossible to tell anything without an idea of where it is.  
> **username_2**: Flow speed can be a function of depth after which you can consider sedimentology to get an idea of grain size . This  will determine the extent of deposition which decides shape of islands . More : Hjulström curve  

---

## 1 answers

### Answer by username_3 on 2016-12-29. Score: 5

The island morphology isn't necessarily an indication of the river's depth because the river can be bimodal, with shallows and deeply incised trenches. One thinks of the River Congo which has many islands, but depths of up to 220 metres in its main incised channel. That said, however, if the river has a multi-channel, heavily braided morphology, as in the Waimakariri in New Zealand, or the Brahmaputra in Assam, then one can be fairly certain that the intense sediment load would have filled in any deep pools (excluding local scour in sharp bends, caused by super-elevated flow). In such cases, one may assume a shallow river profile, governed only by storm-flow peak stages.
Where there are few or no islands coupled with geomorphologic indications of rapid cut back or rejuvenation, such as the Mekong upstream of its delta, then one may suspect very deep channel profiles. In general though, islands and bank morphology are not reliable indicators of a river's cross section.


---

