Location: Watershed Physical Processes Research2012 Annual Report
1a. Objectives (from AD-416):
Improve science components for the RUSLE2 conservation planning tool and facilitate incorporation of these improvements into the functional RUSLE2 model implemented by NRCS. Specifically, support implement by National Resource Conservation Service (NRCS) of improved modeling of pasture, hay, and other perennial vegetations; track management effects on soil organic matter and link to sediment characteristics; develop and incorporate an ephemeral gully component; support ARS efforts to expand RUSLE2 to 2-D landscape modeling; and support NRCS implementation of this science, document science improvements.
1b. Approach (from AD-416):
Incorporate into RUSLE2 the following: track changes in soil organic; effects of organic matter on eroded sediment size distribution based on literature analysis, lab, and field research; an ephemeral gully component based on an improved CREAMS approach; support implementation of new perennial vegetation science; and expand RUSLE2 to a 2-D landscape approach incorporating impacts of runoff redirection and deposition. Develop materials for National Resource Conservation Service (NRCS) explaining those changes and provide implementation assistance.
3. Progress Report:
The agreement project objectives on which progress was made during this period include the following: 1) improvement in the modeling of pasture, hay, and other perennial vegetations; 2) significant re-writing of the code and algorithms to support the ARS RUSLE-2D effort; and 3) support of external efforts (including especially the Natural Resources Conservation Service (NRCS) National Resources Inventory (NRI) effort) using the RUSLE2 dynamic linked library (dll). RUSLE2 has been significantly improved in how it handles pasture, hay, and other perennial vegetation. These improvements have been primarily in trouble-shooting how the program works within the RUSLE2 management and profile, as well as adding some new features, such as how the height of the vegetative regrowth responds to forage removal events. In addition, as a response to questions raised by NRCS national implementation, additional minor improvements have been made. The ARS efforts to expand RUSLE2 technology to a 2-D landscape model include several key elements that must be addressed. The previous report 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 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 testing this code and correcting bugs in it, and in optimizing the code to increase speed and calculation efficiency. Various other natural resource programs are using the RUSLE2 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 management Application Program (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 a substantial amount of effort has gone into trouble-shooting use of the dll for these uses.