Project Number: 6408-13000-018-38
Project Type: Reimbursable

Start Date: Jun 01, 2008
End Date: Aug 31, 2009

Objective:
The research objectives for National Sedimentation Laboratory (NSL) in this project would be to investigate the role of S.erectum on flow roughness, erosion resistance to hydraulic forces, geotechnical root reinforcement, and the stability of streambeds and banks.

Approach:
(a) A series of rooting characteristics of plants will be obtained through measurements of: ¿ root tensile strength at failure conducted along a wall of a trench using a pulling device from USDA that monitors strain and stress during loading of individual roots; ¿ uprooting strength obtained using a similar device built by the USDA; ¿ root size, length and density of uprooted plants determined from scanned imagery; and ¿ root density, spacing and size from exposures in cut trenches. Data from this experimental work will be applied to the USDA fiber-bundle model RipRoot, which incorporates progressive root breaking during mass failure, to calculate increases in bank strength/cohesion by root reinforcement. (b) Direct measures of above-ground biomass will be obtained during the winter (senescent) and summer (peak growth) stages to characterize the seasonal range in canopy development. (c) Flume experiments using USDA facilities will directly measure hydraulic resistance to flow for specimens of varying growth stage and biomass. Experiments will be conducted to examine the hydraulic resistance of S. erectum at different stages of growth and at different stem densities. Tests will also involve removal of above ground biomass to test the effect of different root densities on soil erodibility.