Moving average will do the job!

https://en.wikipedia.org/wiki/Moving_average

https://www.excel-easy.com/examples/moving-average.html

Regards,

Aleš

Hi Blessing Adeoti ,

As Ales Fidler has rightly suggested a moving average smoothing or in my experience a moving median filter might help.

Regards,

Samya

Using Fill tool (from Spatial Analyst) in the Raster(DEM) is useful if you know those sinks(depressions) are wrong and have to be corrected from this point onward. It'll fill all the depressions so the river L-section will have continuously flowing elevations. But if your objective is not to correct the surface but only the L-section then go with other's answer.

I agree with the previous answer. First, it would generate flowpaths, or rivers, in a previous preprocessing with tools like pit-filling type, then I would use vector (of river path - also thalweg) created to make the longitudinal river profile.

I hope you find it useful.

Thank you all for the advice: Ales Fidler Samyadeep Ghosh Gaurav Atreya Victor Hugo Burgos .

@Gaurav Atreya fill tool was my very point if reference, I did used it, my guess is that the dams (about two) constructed along the L-section my be affecting it.

How did you get River L-section? If you used 'fill' tool then the 'flow direction' and 'flow accumulation' to get the river L-section then there shouldn't be any abnormality like that as the generated L-section will have no positive slope. If you have obtained the river L-section from different method and DTM is from different source, that maybe the problem.

Thank you @Gaurav Atreya