Progress 03/05/99 to 03/04/04
Outputs
4. What were the most significant accomplishments this past year? D. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and the School of Geography, University of Nottingham. Additional details of research can be found in the report for the parent project 6408-13000-012-00D Integrated Analysis of of Landscape Processes for Management of Agricultural Watersheds. Results of continued research on suspended-sediment loads across the United States has identified that streambanks are a dominant source of sediment in disturbed, agricultural watersheds. Identification of sediment-source areas is critical for designing appropriate strategies for conservation in agricultural watersheds. Research on suspended-sediment loads in stable and unstable stream systems were combined with numerical-modeling of upland and channel processes to discriminate between upland and channel sources, and to determine "background" sediment
loadings. Results of this research are critical in evaluating off-site impacts by identifying channels as a major source of sediment and for correctly evaluating BMPs and conservation measures.
Impacts
(N/A)
Publications
- Simon, A., and Collison, A.J.C. Scientific basis for streambank stabilization using riparian vegetation. (Abs). 2000. American Geophysical Union. Spring Meeting. EOS. v. 81.
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Progress 10/01/02 to 09/30/03
Outputs
4. What were the most significant accomplishments this past year? D. This report serves to document research conducted under a specific cooperative agreement between the ARS and the School of Geography, University of Nottingham, UK. Additional details of the research can be found in the report for the parent project 6408-13000-012-00D Integrated Analysis of Landscape Processes for the Management of Agricultural Watersheds. Research was conducted on the hydrologic and mechanical effects of riparian vegetation on bank stability. Nests of digital tensiometers were monitored under several vegetative treatments including a control (open) deciduous trees, coniferous trees, and deep-rooting grasses in the Goodwin Creek Bendway Research site, Mississippi. These data were used to determine the difference in shear strength and resistance to bank failure under the different treatments during different times of the year. Measurements of the tensile strength, size, and
distribution of roots provided data on bank-strength enhancement by root reinforcement. Sycamore and river birch provide the greatest increases in strength due to roots while black willow and sweet gum provide considerable less root reinforcement. Several common species were planted in inverted culverts and monitored with digital tensiometers to determine the unique hydrologic characteristics of each species. Results show that the hydrologic effect of trees in drying out streambanks provides greater increases in shear strength then does the relatively shallow (to 1.0 m) root systems. Sycamore and River birch again provide greater strength than does black willow by removing water from the bank. Results of this work have been incorporated into a bank-stability model and placed on the Web providing access to stakeholders and the research community.
Impacts
(N/A)
Publications
- Simon, A., and Collison, A.J.C. Scientific basis for streambank stabilization using riparian vegetation. (Abs). 2000. American Geophysical Union. Spring Meeting. EOS. v. 81.
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Progress 10/01/01 to 09/30/02
Outputs
4. What was your most significant accomplishment this past year? This report serves to document research conducted under a specific cooperative agreement between ARS and the University of Nottingham, UK. This project is associated with parent project 6408-13000-012-00D Integrated Analysis of Landscape Processes for the Management of Agricultural Watersheds. No progress to report.
Impacts
(N/A)
Publications
- Simon, A., and Collison, A.J.C. Scientific basis for streambank stabilization using riparian vegetation. (Abs). 2000. American Geophysical Union. Spring Meeting. EOS. v. 81.
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Progress 10/01/00 to 09/30/01
Outputs
1. What major problem or issue is being resolved and how are you resolving it?
2. How serious is the problem? Why does it matter?
3. How does it relate to the National Program(s) and National Component(s)?
4. What were the most significant accomplishments this past year?
D. This report serves to document research conducted under a specific cooperative agreement between the ARS and the School of Geography, University of Nottingham, UK. Additional details of the research can be found in the report for the parent project 6408-13000-010-00D Integrated Analysis of Stream/Watershed Processes for Rehabilitation of Agricultural Watersheds. Research was conducted on the hydrologic and mechanical effects of riparian vegetation on bank stability centered in the Goodwin Creek Experimental Watershed, Mississippi. Nests of digital tensiometers were installed and monitored under several vegetative treatments, including a control on (open) deciduous trees, coniferous trees and deep-rooting grasses. These data were used to determine the difference in shear strength and resistance to bank failure under the different treatments during different times of the year. In addition, measurements of the tensile strength of roots, in combination with determining the number
and sizes of roots, provide data on strength enhancement by root reinforcement. Sycamore and pine provide the greatest increases in strength due to roots while black willow and sweet gum provide considerable less root reinforcement. Results show that the hydrologic effect of trees in drying out streambanks provides greater increases in shear strength than does the relatively shallow (to 1.0 m) root systems. Results of this ongoing work have been incorporated into the ARS bank-stability model and placed on the Web so it can be accessed by the research community.
5. Describe the major accomplishments over the life of the project including their predicted or actual impact.
6. What do you expect to accomplish, year by year, over the next 3 years?
7. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end user (industry, farmer, other scientists)? What are the constraints if known, to the adoption & durability of the technology product?
8. List your most important publications in the popular press (no abstracts) and presentations to non-scientific organizations and articles written about your work (NOTE: this does not replace your peer-reviewed publications which are listed below)
Impacts
(N/A)
Publications
- Simon, A., and Collison, A.J.C. Scientific basis for streambank stabilization using riparian vegetation. (Abs). 2000. American Geophysical Union. Spring Meeting. EOS. v. 81.
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Progress 10/01/99 to 09/30/00
Outputs
1. What major problem or issue is being resolved and how are you resolving it?
Channel erosion by stream bank failures is the principle source of sediment in unstable streams. To improve our predictive capabilities of bank-failure frequency and stable-bank geometry, we must understand the interaction of bed, bank, and vegetative processes operating on streambanks. Field and laboratory experiments are conducted to (1) characterize erosion of failed and in-situ bank material, (2) measure forces involved in removal of bank-toe material, and (3) characterize the strength of riparian tree roots of various species under different soil water content.
2. How serious is the problem? Why does it matter?
Thousands of miles of channels in the United States are experiencing accelerated rates of erosion (EPA, 1998). Channel instability leads to rapid deepening and widening of the stream, the loss of agricultural land, threatening infrastructure adjacent to the stream, and excess rates of sediment which degrades the environmental quality of the stream.
3. How does it relate to the National Program(s) and National Component(s)?
This project relates to (201) Water Quality Management. The research components of Agricultural Watersheds, Water Quantity Management, Water Quality Management, Data Bases, Models and Decision Support Systems will be directly addressed.
4. What were the most significant accomplishments this past year?
A. Single Most Significant Accomplishment during FY 2000 year: (1) Erosion of sediment from streambanks causes significant amounts of land loss and is a major pollutant to the nation's river systems. (2) The relative contributions of different riparian species to enhancing bank stability have been quantified with willows (a commonly used specie) being the weakest and sycamore, providing the greatest increase in bank strength. (3) Vegetative treatments to enhance bank stability can now be quantified and restoration techniques modeled accurately by adding the effects due to root reinforcement into the ARS bank-stability model developed at the National Sedimentation Laboratory. B. Other Significant Accomplishment(s), if any: None to report. C. Significant Accomplishments/Activities that Support Special Target Populations. None to report.
5. Describe the major accomplishments over the life of the project including their predicted or actual impact.
(1) Determined the tensile strengths of the roots of common riparian species, which in combination with data on root distributions allowed estimates of the enhancement of bank stability by root reinforcement. (2) Resistance of failed cohesive blocks to erosion by flow is controlled not only by particle weight, but by a suction force between the base of the block and the underlying substrate.
6. What do you expect to accomplish, year by year, over the next 3 years?
(1) Results of the block entrainment experiments will be incorporated into the CONCEPTS channel evolution model in 2001; (2) roots of additional woody and grassy species will be tested in 2001; (3) experiments on the resistance of root wads to pull from soils will be conducted in 2000 and 2001; and (4) reinforcement of streambanks by tree roots will be incorporated into the CONCEPTS channel-evolution model in 2001.
7. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end user (industry, farmer, other scientists)? What are the constraints if known, to the adoption & durability of the technology product?
Reporting of results from this study has occurred at technical meetings such as the 1999 and 2000 American Society of Civil Engineers International Meeting on Water Resources Engineering and at at training courses sponsored by the Corps of engineers and the US Geological Survey.
8. List your most important publications in the popular press (no abstracts) and presentations to non-scientific organizations and articles written about your work (NOTE: this does not replace your peer-reviewed publications which are listed below)
None.
Impacts
(N/A)
Publications
- Simon, A., and Collison, A.J.C. Scientific basis for streambank stabilization using riparian vegetation. (Abs). 2000. American Geophysical Union. Spring Meeting. EOS. v. 81.
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Progress 01/01/99 to 09/30/99
Outputs
1. What major problem or issue is being resolved and how are you resolving it? Erosion of channel sediments by bank failures is the principle source of sediment in unstable streams. To improve our predictive capabilites of bank-failure frequency and stable-bank geometry, we must attain a more complete understanding of the interaction of bed, bank, and vegetative processes operating on streambanks. In particular, the role of hydraulic (flow) and geotehcnical (gravitational) forces acting on in situ and failed material at the bank toe must be quantified in order to accurately account for sediment inputs from this source and the steepening of the bank during periods of low and moderate flows. Given the popularity of using vegetative erosion-control measures on streambanks, quantification of the hydrologic and geotechnical affects of riparian vegetation on bank stability is extremely limited. To accurately model bank stability, the variability and applicability of
reinforcement by roots and vegetation's role in altering the distribution of water pressures within streambanks (pore-water pressures) during different times of the year must be accounted for. Field and laboratory experiments for erosion by flow (entrainment) of failed blocks and in situ bank-toe material will be conducted. Testing of the forces involved in block entrainment and particle-by-particle erosion of bank-toe material required the development of new field instruments. Controlled field experiments on the strength of riparian tree roots of different species will be conducted along with paired streambanks with and without woody vegetation to test differences in pore-water pressures and, therefore, bank-material strength. 2. How serious is the problem? Why does it matter? Thousands of miles of channels in the United States are experiencing accelerated rates of bank failure and channel widening. With sediment contributions from channel banks representing the major source of
sediment in these systems, a means to accurately define bank-stability relations and stable-channel forms is essential for erosion control. Channel instability leads to rapid erosion and widening of the stream, the loss of agricultural land, threatening infrastructure adjacent to the stream, and excess rates of sediment which degrades the environmental quality of the stream. 3. How does it relate to the National Program(s) and National Component(s) to which it has been assigned? This project directly addresses the needs and projected outcomes of the following USDA-ARS National Programs: (1) Agricultural Watersheds, Water Quantity Management on Agricultural Lands and Stream Channel Systems, Water Quality Management on Agricultural Lands, and Water Resources Data Bases, Models and Decision Support Systems within the Water Quality and Management Program; and (2) Agricultural Watersheds and Conservation Management Practices within the Soil Quality and Management Program. 4. What were the
most significant accomplishments this past year? Resistance of bank-toe material is not due only to the materials' weight. During the past year field experiments on failed, cohesive blocks were conducted along several DEC streams and laboratory experiments were conducted in a flume specifically designed to hydraulically represent bank-toe regions of incised channels. To date, block entrainment was predicted as a function of block size and weight. However, investigations revealed an additional force which bonds blocks and their underlying surface. This force is the result of suction (similar to the force exerted by plants when they remove soil water) and an instrument was developed by which to measure the magnitude of this force. Measurements beneath the blocks indicate that the force due to suction alone may be as much as 3.5 kPa in summer and 1.8 kPa in winter. These values are significant in that they are similar to the internal strength of the material itself. These results are
important because the additional force needs to be accounted for to accurately model the processes at the bank toe which ultimately determine the angle and stability of the channel bank. Tests of the strength of riparian tree roots shows that sycamore roots are 2-3 times stronger on average than those of other tested, common riparian species such as river birch, black willow, and sweet gum. 5. Describe the major accomplishments over the life of the project including their predicted or actual impact. First Year, see question 4, above. 6. What do you expect to accomplish, year by year, over the next 3 years? During the next three years the following tasks are expected: 1) results of the block entrainment experiments will be incorporated into a numerical scheme and added to the CONCEPTS channel evolution model in 2000; 2) Roots of additional woody-riparian species will be tested in 2000; 3) Reinforcement of streambanks by tree roots will be incorporated into the NSL's bank-stability
algorithm and added to the CONCEPTS channel-evolution model in 2000 to 2001; 4) shear-box experiments on the resistance of root wads to pull from soils will be conducted in 2000 and 2001. 7. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end user (industry, farmer, other scientists)? What are the constraints if known, to the adoption & durability of the technology product? Reporting of results from this study has occurred at technical meetings such as the 1999 ASCE International Meeting on Water Resources Engineering and at various training courses sponsored by the Corps of Engineers, Waterways Experiment Station, EPA, and the USGS. 8. List your most important non-peer reviewed publications and presentations to non-scientific organizations, and articles written about your work(NOTE: this does not replace your peer reviewed publications which are listed below). none
Impacts
(N/A)
Publications
- WOOD, A., SIMON, A., DOWNS, P. and THORNE, C. 1999. Bank-toe processes in incised channels: The contribution of apparent...blocks. Accepted by International Water Res. Conf. ASCE. Seattle, WA. 8/7/1999.
- WOOD, A., SIMON, A., DOWNS, P. and THORNE, C. 1999. The role of apparent cohesion in the entrainment of failed bank materials. Accepted by Hydrological Processes August 25, 1999.
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