Information and code (ArcGIS Pro 2.4, ArcGIS 10.x, and Arc/Info workstation) used to calculate
cumulative downhill slope length, maximum downhill slope angle, and flowdirection
from a DEM.
- RUSLE LS factor calculations. For ArcGIS Pro.
- Directional slope calculations
- Download a copy of the python code (for ArcGIS 10.x, not Pro) HERE. Readme information at this link.
- RUSLE Calculations (For old ArcInfo workstation. Yup, it's legacy code!)
- RUSLE Version 4 (an AML): (posted on 12/018/2003) - Version 4
is intended to correct an order-of-operations error in earlier versions
that affected the computation of the slope steepness constituent,
generally yielding higher (by about 5-10%) LS factor values. This
is the latest version of the RUSLE code that was modified from the
original USLE-based code by Rick
D. Van Remortel and Mathew E. Hamilton of the Remote Sensing
and Technical Services Department, Lockheed Martin Environmental
Services. Calculates LS Factor using DEM data according to RUSLE-based
criteria. See the AML itself for more info. Download the UNIX
version or the Windows Version.
(windows version last tested under 9.1 [run from the arc prompt in workstation]
on 16 Feb, 2007).
- Output Files
- DEM Results
- dem_fill = filled-sink DEM
- dem_fill_b = filled-sink DEM + 1-cell outer buffer
- down_slp_ang = downlsope angle in degrees
- flowdir_in = flow direction entering a cell
- flowdir_out = flow direction leaving a cell
- flowdir_out_b = flow direction leaving a cell + 1-cell
- m_slpexp = slope exponent (m) used in final L-constituent
- nd_chg2 = nodata check to check progress of slope-length
- slp_lgth_beg = initial slope length used to begin
- slp_lgth_cum = cumulative slope length at completion
of each slope length iteration
- slp_lgth_cell = length of cell with respect to flowdir
- slp_end_fac = factor (threshold) that will end slope-length
- slp_lgth_ft = slope length expressed in feet, used
as input to L and S factor calculations
- L and S Factor Calculations
- slp_lgth_max = renamed slp_lgth_cum from previous
- slp_lgth_prev = renamed slp_lgth_max for checking
- *_ruslel = calculated L-constituent of LS factor
- *_rusles = calculated S-constituent of LS factor
- *_ruslels2 = final output grid; calculated grid value
is LS factor x 100 which retains significant digits
within the integer grid and minimizes grid storage requirements
(actual ls_factor value is an additional side attribute
in .vat file
***And a notice to users of ALL sets of code -- this is iterative software
and will run on your entire grid a number of times equal to one more than
the maximum number of cells in the longest flowpath on the grid.
Yes, this means that the code can, sometimes, run
for a number of days. The Arc/Info AMLs are constantly reading and writing
to a disk (fast harddrives are good......).
Please feel free to use any of the code posted on this page. The original
work came from my dissertation, and the details can be found either there
or in the Computers, Environment, and Urban Systems paper. The
Environment and Planning A paper is listed as a more general reference
to work using erosion modeling as a part of a larger project. The Cartography
papers discuss the slope length algorithms in more detail, including the
differences/similarities of the IDRISI/ARC and USLE/RUSLE code. The 2000, 2001, and 2004 papers represent updates of the
1994 work for both the USLE and RUSLE.
The 2020 thesis is the most recent incarnation of this work, and contains significant updates and improvements.
the Dunn and Hickey paper discusses differences among the different available
slope angle algorithms - including the maximum downhill slope angle algorithm
which I prefer. The Hickey, Quinn, and Schag paper follows up on this with some newerPython code.
- Hickey, R., 1994, Design and Simulation of Smelter Reclamation Strategies
using an Environmental Decision Support System. Ph.D. dissertation.
Department of Geography, University of Idaho, Moscow, ID.
- Hickey, R, A. Smith, and P. Jankowski, 1994, Slope length calculations
from a DEM within ARC/INFO GRID: Computers, Environment and Urban
Systems, v. 18, no. 5, pp. 365 - 380. DOWNLOAD
- Hickey, R. and P. Jankowski, 1997, GIS and Environmental Decision-making
to aid smelter reclamation planning: Environment and Planning A,
v. 29, pp. 5 - 19.
- Dunn, M. and R. Hickey, 1998, The effect of slope algorithms on slope
estimates within a GIS. Cartography, v. 27, no. 1, pp. 9 - 15.
- Hickey, R., 2000, Slope Angle and Slope Length Solutions for GIS.
Cartography, v. 29, no. 1, pp. 1 - 8. DOWNLOAD
- Van Remortel, R., M. Hamilton, and R. Hickey, 2001, Estimating the
LS factor for RUSLE through iterative slope length processing of DEM
elevation data. Cartography. V. 30, no. 1, pp. 27 - 35. DOWNLOAD
- Hickey, R., E. Burns, J. Bolte, and D. Walker, 2005, Development
of a Statewide Erosion Vulnerability Screening Tool for Oregon, Geography
Online . V. 5, no. 2.
- Van Remortel, R., R. Maichle, and R. Hickey, 2004, Computing the
RUSLE LS Factor through Array- based Slope Length Processing of Digital
Elevation Data Using a C++ Executable. Computers and Geosciences.
V. 30, No. 9-10, pp. 1043-1053. DOWNLOAD
- Moody, A., 2020, Comparing RUSLE LS Calculation Methods Across Varying DEM Resolutions. Unpublished master’s thesis. Central Washington University, Ellensburg, WA, USA. DOWNLOAD PDF