Why not?

There are some adaptations to mountainous sub-watersheds

http://www.sciencedirect.com/science/article/pii/S1674987111001034

https://link.springer.com/article/10.1007/s10661-007-9894-9

Considering that L-S factor will specifically account for slope length and steepness and that you have a detailed DEM, why not applying the RUSLE equation and contrast the results with available field data?

All the best.

http://topsoil.nserl.purdue.edu/nserlweb-old/isco99/pdf/ISCOdisc/SustainingTheGlobalFarm/P042-BY%20Liu.pdf

http://www.saga-gis.org/saga_tool_doc/2.1.3/ta_hydrology_22.html

http://www.sciencedirect.com/science/article/pii/S1674987111001034

https://link.springer.com/article/10.1007/s10661-007-9894-9

Article Slope Gradient Effects on Soil Loss for Steep Slopes

Thanks Paulo for your answer. RUSLE has been widely used in assessing erosion of watersheds, no doubt in that. I am focusing on rain induced soil erosion in Nepal hills during monsoon and not watching erosion in watershed.

We generally calculate LS by following method

1. Calculating Flow Direction from clipped watershed DEM layer using Flow Direction tool

2. Calculating Flow Accumulation with Flow Accumulation tool using flow direction data as the input raster

3. Calculate slope of watershed in degrees using Slope tool using clipped watershed DEM as the input layer

4. Copying and pasting the LS-factor formula into Raster Calculator

My concern, here is, can we determine flow direction and flow accumulation in hilly slopes (where rain induced erosion is the main source of degradation)?????

Some additional readings from GRASS and SAGA. Your problem may be also related to landslide/debris flow models.

https://grass.osgeo.org/grass73/manuals/r.watershed.html

https://grass.osgeo.org/grass64/manuals/r.flow.html

https://grass.osgeo.org/grass72/manuals/addons/r.landscape.evol.html

http://www.saga-gis.org/saga_tool_doc/2.2.4/ta_hydrology_0.html

Thanks Paulo for the documents link.

IntErO software (2011)

www.agricultforest.ac.me/Spalevic/IntErO

Examples:

www.agricultforest.ac.me/Spalevic

www.agricultforest.ac.me/Spalevic/Reference