# Calculating slope length using LS-tool

Does anyone know how to get LS-tool mentioned in Zhang et al 2013. https://www.researchgate.net/publication/256938578_Extension_of_a_GIS_procedure_for_calculating_the_RUSLE_equation_LS_factor

I tried using the Raster calculator in ArcMap 10.3.1 using the following formula by Bizuwerk et al., (2008).

LS = X/22.1m (0.065+0.045S+0.0065S^2
but I got only 0 value.

I found about LS tool after I researched on other ways to calculate slope length but can't find any place to access LS tool.

I would be really thankful if someone could help me find a way to either access LS tool or any other efficient and precise way to calculate slope length.

• Isn't is flow length from spatial analyst with direction = upstream? Jan 26 '16 at 1:27
• From a glance, it appears that the LS-Tool referenced in the article is actually created by the author or the research group behind it. What exactly are you trying to accomplish? There may be another work around for it. Jan 26 '16 at 2:02
• Thank you. Yes, the LS-tool is developed by the research group who published the paper, so I was trying to see if anybody knows how to access it. I am trying to calculate the slope length factor, one of the soil erosion factors in the USLE equation. Jan 26 '16 at 20:45

In the paper mentioned in your question, the authors suggest the use the unit contributing area for the slope length. This unit contributing area can be obtained in ArcGIS using "flow accumulation" tool in Spatial analyst toolbox. Flow accumulation, by default, gives you a value in pixels, so you need to multiply by the pixel size before you divide by 22.13 (coefficient of the RUSLE equation). The best method would consist in creating a weighting raster with the m value and use it when you compute the accumulation.

Maybe you could try saga-gis software for creating LS. I remember that there was a module called LS Factor to create that. Here is documentation for that module: http://www.saga-gis.org/saga_module_doc/2.1.3/ta_hydrology_22.html

• Thank you Roman. It would be more helpful if I can find a way to do it in arcmap since I am using it for all other analysis. Jan 26 '16 at 20:45
• Have you tried archydro tools for arcgis? Jan 31 '16 at 9:37
• No, I have not tried using archydro tools. I used the formula in Raster calculator. Thank you for your help though. Feb 22 '16 at 21:13

I am using the ArcGIS Flow Length tool.

Especially the DOWNSTREAM calculation option.

This option narrows the length of the slope from the DEM data

• Hi Miguel, could you translate your answer to english? As you know, Gis SE is about sharing knowledge, which is best done using a common language. Thank you in advance and welcome! Oct 30 '19 at 6:55