Arc Hydro Tools LS Factor Equation Slope Angle Exponent

JD_Lancaster — Tue, 14 Oct 2025 23:56:04 GMT

Hello, the equation used in the Create LS Raster tool in Arc Hydro Tools H & H Modeling, Erosion Tools is based on Moore et al. (1993) except that the slope angle exponent is 1.4 and not 1.3 as presented in the original equation. I can't seem to find a reference to using 1.4 over 1.3. Why does the equation in the tool use 1.4 and is there a specific reference for this?

The equation as it is in the Arc Hydro code:

LS= Power(facc * cell resolution / 22.1, 0.4) * Power(Sin(slpdeg * 0.01745) / 0.09, 1.4) * 1.4

Moore, I.D., Turner, A.K., Wilson, J.P., Jenson, S.K. & Band, L.E. (1993). GIS and
land-surface-subsurface process modeling. In: Goodchild, M.FR., Parks, B.O.
& Steyaert, L.T. (eds): Environmental modeling with GIS, p. 196-230.

Thanks!

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Arc Hydro Tools LS Factor Equation Slope Angle Exponent