2013 Annual Report
The ARS efforts to expand RUSLE2 technology to a 2-D landscape model include several key elements that must be addressed. Previous reports included discussion of the complete re-writing of the code to perform the calculations on a cell rather than slope segment basis. The older profile-based approach was then adapted so that it could generate cells and define the relationships between those, which on testing proved (as hoped) to give the same answers as did the older calculations. As the cell-based calculations become more efficient, the hope is to completely do away with the segment-based calculations. During this reporting period, significant progress was made in optimizing the code to increase speed and calculation efficiency, including especially refactoring of the code to require less use of the RUSLE engine.
Various other natural resource programs are using the RUSLE2 Dynamic Link Library (DLL), which allows those programs to set RUSLE parameters and get RUSLE2 results without using the RUSLE2 interface. Examples of these programs include the Soil Nutrient Application Planner (SNAP) from Wisconsin, the Manure Management Planning (MMP) tool at Purdue, and most notably the Natural Resource Inventory (NRI) effort for NRCS, based at the University of Iowa. The latter especially will make a huge number of calls to the RUSLE2 program, and is setting inputs in new ways. During this reporting period some effort has gone into trouble-shooting use of the dll for these uses.
Finally, the code was adapted to make use of the Rothemsted carbon model (ROTH-C) approach to modeling carbon sequestration in the soil. This included linkage of the RUSLE decomposition routines to that approach. This method appears to work well, but will require some calibration of the approach to adequately represent various land uses and soil moisture effects.