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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED ASSESSMENT AND ANALYSIS OF PHYSICAL LANDSCAPE PROCESSES THAT IMPACT THE QUALITY AND MANAGEMENT OF AGRICULTURAL WATERSHEDS

Location: Watershed Physical Processes Research Unit

2008 Annual Report


1a.Objectives (from AD-416)
Assisting agricultural landowners to produce food and fiber in an economically and environmentally sustainable manner requires an integrated approach to land management practices, and protection of streams and impounded waters. This project contributes to those goals by developing and testing practices based on a scientific understanding of hydrologic, erosion, and sedimentation processes. This project also contributes to the Conservation Effects Assessment Project (CEAP) with the goal of quantifying effects of conservation management in selected CEAP watersheds, two of them managed within this project. To meet these challenges, the focus of all the proposed research activities has been chosen to evaluate innovative practices and to fill knowledge gaps in watershed models currently in use. This is realized by: (1) developing databases of weather, soil, land use, soil conservation practices, runoff, sediment yield, and nutrient data for assessing the impacts of conservation practices on the Goodwin Creek and Topashaw Creek CEAP watersheds; (2) evaluating relative magnitudes of sources and fates of sediment in CEAP-benchmark and other watersheds, and develop methodologies to establish criteria for identifying agricultural watersheds impaired by clean-sediment loadings; (3) quantifying and validating the uncertainties of model predictions at field, farm, and watershed scales for Yazoo River Basin CEAP sub-watersheds; (4) conducting field and laboratory studies to quantify the surface and subsurface flow processes governing the initiation, development and migration of ephemeral gullies and the effect of conservation management practices on infiltration, erosion, and transport; (5) conducting field and laboratory studies to improve the understanding of stream channel processes including channel evolution, sediment transport, protection of erodible embankments, edge-of-field gullies, and sediment deposition in impounded waters for CEAP and other watersheds; and (6) improving models to identify sources of sediment, determine their fate and transport within watersheds with complex channel drainage networks, and evaluate watershed water quality impacts in terms of implementation of land conservation and stream rehabilitation practices.


1b.Approach (from AD-416)
An extensive body of literature exists that describes plot or field-scale conservation practices aimed at reducing soil erosion or enhancing water conservation. However, results from plot- and field-scale studies are limited in that they cannot capture the complexities and interactions of conservation practices at the whole-farm level or at the watershed scale. Soil erosion and sediment movement processes involve the interactions of land management practices with climate, weather, soil, and landscape properties. Concentrated runoff and subsurface flow results in rill and gully erosion thus increasing soil losses and downstream sediment loads leading to increased costs of crop production, ecological degradation, and impairment of water supplies. This research focuses on developing tools and techniques to quantify the impact of implementing conservation practices within a watershed in the most efficient manner to achieve sustainable and targeted reductions of sediment loadings to the nation’s stream waters to help establish total maximum daily load requirements. New methods to measure and characterize changes in runoff, gully and stream channel erosion, and sediment deposition rates utilizing hydrological, geomorphic, and hydraulic engineering principles, and remote-sensing techniques will be tested in CEAP watersheds within the Yazoo River Basin, and in other watersheds when appropriate. Improved computer models and assessment tools will be provided to evaluate the impact of land conservation and stream rehabilitation practices in the most efficient manner to assist watershed managers achieve sustainable crop production systems and targeted reductions of sediment loadings.


3.Progress Report
In FY 2008, research was performed by nine scientists working in collaboration with many research institutions to assist agricultural landowners in producing food and fiber in an economically and environmentally sustainable manner using an integrated watershed approach to improve land management practices for controlling sedimentation, and for protection of streams and impounded waters. This required the development and testing of practices based on a scientific understanding of hydrologic, erosion, and sedimentation processes. This project contributed to the Conservation Effects Assessment Project (CEAP) by quantifying the effects of conservation management in two watersheds managed within this project. This work addressed three problem areas of the Water Availability and Water Management National Program 211 Action Plan.

For National program problem area 1:.
1)The effects of enrolling erodible lands in the Conservation Reserve Program (CRP) and in-stream grade stabilization structures using measured rainfall, runoff, and sediment concentration data and model simulations on the 2132 ha Goodwin Creek Experimental Watershed in north Mississippi. The combined effect of the grade control structures and the change of crop lands to a CRP-state (reducing cultivated land from 26 to 8%) was to reduce sediment yields by 78% near the outlet of the watershed;.
2)Target or “reference” sediment loads and yields were quantified for stable streams in all of the Level III ecoregions of the southeastern United States. To increase applicability and to provide a functional link to aquatic ecology, sediment data were transformed into the frequency and duration that a range of suspended-sediment concentrations are maintained or exceeded. Sediment frequency-duration curves for “reference” conditions were calculated by Level III ecoregion to serve as a fundamental basis for establishing target sediment-transport conditions.

For National program problem area 4:.
1)The critical processes that influence ephemeral gully erosion and have been incorporated into the USDA Annualized Agricultural Non-Point Source pollution model. The influence of agricultural practices can be evaluated with the model for their effect on sediment delivered from sheet and rill erosion, as well as from ephemeral gully erosion;.
2)Several different breakwater protection methods using secured irrigation pipes were tested. Approximately 300 feet of each arrangement were deployed, and 40 hours of continuous wind and wave data were collected with reductions in wave amplitude observed.

For National program problem area 5:.
1)The combination of rainfall with soil pipe flow was shown to result in reestablishment of ephemeral gullies with extensive soil losses. These findings explain the reoccurrence of ephemeral gullies in the same locations despite land management efforts to control their development;.
2)NSLs Bank-Stability and Toe-Erosion Model has been enhanced to be used iteratively over annual hydrographs, and in a variety of environments to predict sediment loadings from streambanks. By conducting simulations under existing and mitigated conditions, potential load reductions are calculated.


4.Accomplishments
1. Conservation practice effects on sediment load.

Knowledge of the effect of agricultural management practices on sediment yield has been derived predominantly from studies on plots or field-sized watersheds which may not be representative of the scales and complexity that typically exist on larger watersheds. Effects of enrolling erodible lands in the Conservation Reserve Program (CRP) and in-stream grade stabilization structures were evaluated using measured rainfall, runoff, and sediment concentration data and model simulations on the 2,132 ha Goodwin Creek Experimental Watershed in north Mississippi. The combined effect of the grade control structures and the change of crop lands to a CRP- state (reducing cultivated land from 26 to 8%) was to reduce sediment yields by 78% near the outlet of the watershed. This study provided a quantitative assessment of the effects of converting crop lands to a CRP-state and of grade control structures in the channels of the watershed. This type of information is needed by watershed managers seeking to reduce sediment loads and is useful to evaluate the performance of watershed simulation models.

This research supports the Water Availability and Water Management National Program 211, Problem Area 1--Effectiveness of Conservation Practices, Product 2.

2. Tillage significantly effects ephemeral gully erosion.

Ephemeral gully erosion can be a significant source of sediment from agricultural fields as a result of tillage operations. The important processes that influence ephemeral gully erosion have been incorporated into the USDA Annualized Agricultural Non-Point Source pollution model (AnnAGNPS) by utilizing procedures developed from laboratory basic research studies. The influence of agricultural practices can be evaluated with the model for their effect on sediment delivered from sheet and rill erosion, as well as from ephemeral gully erosion. This provides an important tool for action agencies such as the USDA-Natural Resources Conservation Service, when evaluating the effect of agricultural conservation practices at field or watershed scales.

This research supports the Water Availability and Water Management National Program 211, Problem Area 4--Integrated Erosion and Sedimentation Technologies, Product 7.

3. Ephemeral gully erosion (EGE) contributes to between 18 to 73% of the total erosion.

EGE is generally a result of convergent surface runoff but subsurface flow through soil-pipes has been reported to contribute to EGE. Soil-pipes at the head of ephemeral gullies are cutoff when tillage fills in the gully. The combination of rainfall with pipe flow was shown to result in re-establishment of ephemeral gullies with extensive soil losses. These findings explain the reoccurrence of ephemeral gullies in the same locations despite land management efforts to control their development. This work also suggest that conservation practices that focus on controlling the surface runoff may be ineffective if subsurface flow controls are not considered. Locations susceptible to subsurface flow may benefit more from drainage and/or deep rooted vegetation control practices.

This research supports the Water Availability and Water Management National Program 211, Problem Area 5--Watershed Management, Water Availability, and Ecosystem Restoration, Product 2.

4. Successful field testing of innovative levee protection technology.

The techniques commonly used for large-scale embankment protection, such as rip-rap, are too expensive to be a viable solution for the protection of earthen embankments used to store irrigation water. Vegetation cannot be used because of water level fluctuations imposed by irrigation scheduling. Floating breakwaters can be used to reduce wave energy, and are inexpensive relative to other protection methods. Several different methods for securing groups of irrigation pipe were tested in cooperation with personnel from the Lonoke, AR, Irrigation District. Approximately 300 feet of each arrangement were deployed, and 40 hours of continuous wind and wave data were collected. Reductions in wave amplitude were observed, and the information gained is being used to further improve the design and implementation of inexpensive floating wave barriers.

This work contributes to the Water Availability and Water Management National Program 211, Problem Area 4--Integrated Soil Erosion and Sedimentation Technologies.

5. Demonstration of shear stress reduction by sand added to gravel beds.

Dam removal often results in the addition of large quantities of fine sediment into gravel beds that have been stripped of finer particles by flows rendered free of sediment by passage through or over the dam. The effect of these re-introduced sediments on bed stability and water level are largely unknown. The effect of sands added to clean gravel beds was evaluated using detailed measurements of shear stress over gravel beds with increasing levels of sand relative to gravel elevation, resulting in the quantification of systematic reductions in shear stress with changing sand content in a gravel bed.

This work contributes to the Water Availability and Water Management National Program 211, Problem Area 4--Integrated Soil Erosion and Sedimentation Technologies.

6. Water-quality targets for suspended sediment quantified for the southeastern United States.

Suspended sediment is one of the leading causes of water-quality impairment of surface waters of the United States. Target or “reference” sediment loads and yields (load per unit area) were quantified for stable streams in all of the Level III ecoregions of the southeastern United States. To increase applicability and to provide a functional link to aquatic ecology, sediment data were transformed into the frequency and duration that a range of suspended-sediment concentrations are maintained or exceeded. Sediment frequency-duration curves for “reference” conditions were calculated by Level III ecoregion to serve as a fundamental basis for establishing target sediment-transport conditions. These data are being used by the States to develop TMDLs for sediment.

This research supports the Water Availability and Water Management National Program 211, Problem Area 1: Effectiveness of Conservation Practices, Product 2.

7. Bank stabilization and reductions in sediment loadings from streambanks can be predicted and designed.

Suspended sediment is one of the leading causes of water-quality impairment of surface waters of the United States and recent studies have shown that streambanks are often the major source is disturbed systems. NSLs Bank-Stability and Toe-Erosion Model (BSTEM) has been enhanced to be used iteratively over annual hydrographs, and in a variety of environments to predict sediment loadings from streambanks. By conducting simulations under existing and mitigated conditions, potential load reductions are calculated. Using BSTEM in combination with improved root-reinforcement algorithms that account for species types, ages and distributions, riparian buffers that maximize bank stability can be designed and numerically tested. Similar results were demonstrated using measures (such as rock) that protect against hydraulic erosion of bank toes. Load reductions of 50-85% were predicted in different environments. BSTEM has been disseminated to stakeholders in state and federal agencies around the country for use in these types of applications and its use is taught in workshops at academic institutions and at national technical meetings.

This research supports the Water Availability and Water Management National Program 211, Problem Area 5: Watershed Management, Water Availability, and Ecosystem Restoration, Product 2.

8. An ephemeral gully calculator for RUSLE2.

RUSLE2 is the erosion model that the Natural Resources Conservation Service (NRCS) uses to estimate soil erosion on farmland and to determine farm program eligibility. RUSLE2 does a good job of estimating erosion on hillsides, but it cannot estimate erosion in concentrated flow channels like the “ephemeral gullies” that form in cropped fields. Adding the ability to account for this kind of soil erosion has been identified as a priority need by NRCS. We developed a method that will allow estimation of runoff and ephemeral gully erosion using the information already available in the RUSLE2 databases and hillslope descriptions plus user supplied descriptions of the length and steepness of ephemeral gully segments. When the methods developed are incorporated into RUSLE2, conservation planners will be able to estimate long term average ephemeral gully erosion for any farm field in the continental United States.

This research supports the Water Availability and Water Management National Program 211, Problem Area 4--Integrated Erosion and Sedimentation Technologies, Product 7.

9. 2-D tillage erosion prediction model. Tillage erosion has come to be widely recognized as a major cause of soil degradation that reduces soil productivity, particularly on convex slope positions. A computer model has been developed that correctly predicts the locations and amounts of tillage erosion and deposition and dynamically updates terrain elevation over time to compute how field topography changes through the years. Results can be used to identify areas within fields that are at risk of productivity loss and to predict their rates of degradation as a function of tillage intensity and frequency. Major advances in this model are the capability of simulating tilled and untilled areas within fields, of allowing any pattern of tillage within the field, and of accounting for the development of furrows and berms along field boundaries that can alter runoff paths and hence change water erosion patterns. When incorporated into a geographic information system (GIS) and linked with water and wind erosion models, this model will be a valuable component of an integrated soil erosion model.

This research supports the Water Availability and Water Management National Program 211, Problem Area 4--Integrated Erosion and Sedimentation Technologies, Product 7.


6.Technology Transfer

Number of Web Sites Managed3
Number of Non-Peer Reviewed Presentations and Proceedings16
Number of Other Technology Transfer8

Review Publications
Yuan, Y., Bingner, R.L., Theurer, F.D., Kolian, S.R. 2007. Water Quality Simulation of Rice/Crawfish Within Annualized AGNPS. Applied Engineering in Agriculture, Vol. 23(5): 585-595.

Licciardello, F., Zema, D.A., Zimbone, S.M., Bingner, R.L. 2007. Runoff and Soil Erosion Evaluation by the AnnAGNPS Model in a Small Mediterranean Watershed. Transactions of the ASABE, Vol. 50(5): 1585-1593.

Gordon, L.M., Bennett, S.J., Bingner, R.L., Theurer, F.D., Alonso, C.V. 2007. Simulating Ephemeral Gully Erosion in AnnAGNPS. Transactions of the American Society of Agricultural & Biological Engineers International, Vol. 59(3): 857-866.

Fox, G.A., Chu-Agor, M., Wilson, G.V. 2007. Erosion of Noncohesive Sediment by Groundwater Seepage: Lysimeter Experiments and Stability Modeling. Soil Science Society of America Journal 71(6): 1822-1830.

Wilson, G.V., Mcgregor, K.C., Boykin, D.L. 2008. Corn Residue Impacts on Runoff and Soil Erosion for Different Plant Populations. J. Soil & Tillage Research. 99(2): 300-307, doi.org/10.1016/j.still.2008.04.001.

Wilson, G.V., Cullum, R.F., Romkens, M.J. 2008. Ephemeral Gully Erosion by Preferential Flow Through a Discontinuous Soil-Pipe. Catena, 73(1): 98-106.

Kuhnle, R.A., Jia, Y., Alonso, C.V. 2008. Measured and Simulated Flow Near a Submerged Spur Dike. Journal of Hydraulic Engineering, 134(7): 916-924, doi:10.1061/(ASCE)0733-9429 (2008)134:7(916-924), 2008.

Gordon, L.M., Bennett, S.J., Wells, R.R., Alonso, C.V. 2007. Effect of Soil Stratification on the Development and Migration of Headcuts in Upland Concentrated Flows. Water Resources Research, Vol. 43, W07412, 13 pp.

Diplas, P., Kuhnle, R. A., Gray, J. R., Glysson, G. D., Chapter 5, Sediment Transport Measurements.  in Sedimentation Engineering, Processes, Measurements, Modeling, and Practice, Garcia, M. H., ed., ASCE Manuals and Reports on Engineering Practice No. 110, American Society of Civil Engineers, Reston, Virginia, USA, p. 307-354., 2008. submission date: July 6, 2001;   acceptance date: July 18, 2006.;  publication date:  May 1, 2008

Wren, D.G., Davidson, G.R., Walker, W.G., Galicki, S.J. 2008. The Evolution of an Oxbow Lake in the Mississippi Alluvial Floodplain. Journal of Soil and Water Conservation. 6(3): 129-135.

Wren, D.G., Davidson, G.R. 2008. Practical Implications of Quantifying Ancient Sedimentation Rates in Lakes. Journal of Soil and Water Conservation. 63(3): 89A.

Langendoen, E.J., Simon, A. 2008. Modeling the Evolution of Incised Streams: II. Streambank Erosion. Journal of Hydraulic Engineering, 134(7): 905-915.

Langendoen, E.J., Alonso, C.V. 2008. Modeling the evolution of incised streams: I. Model formulation and validation of flow and streambed evolution components. Journal of Hydraulic Engineering, 134(6): 749-762.

Bennett, S.J., Wu, W., Alonso, C.V., Wang, S.S. 2008. Modeling Fluvial Response to In-stream Woody Vegetation: Implications for Stream Corridor Restoration. Earth Surface Processes and Landforms, 33: 890-909.

Salant, N., Hassan, M., Alonso, C.V. 2008. Suspended Sediment Dynamics at High and Low Flows in Two Small Watersheds. Hydrological Processes, 22: 1573-1587.

Pollen-Bankhead, N., Simon, A. 2008. Enhanced Application of Root-Reinforcement Algorithms for Bank-Stability Modeling. Earth Surface Processes and Landforms, DOI: 10.1002/esp.

Pollen-Bankhead, N., Simon, A., Jaeger, K., Wohl, E. 2008. Destabilization of Streambanks by Removal of Invasive Species in Canyon de Chelly National Monument, Arizona. Geomorphology, doi:10.1016/j.geomorph.2008.07.004.

Simon, A., Doyle, M., Kondolf, M., Shields Jr., F.D., Rhoads, B., McPhillips, M. 2007. Critical Evaluation of How the Rosgen Classification and Associated "Natural Channel Design" Methods Fail to Integrate and Quantify Fluvial Processes and Channel Response. Journal of the American Water Resources Association (JAWRA) 43(5): 1117-1131. DOI: 10.1111/j.1752-1688.2007.00091.x

Simon, A. 2008. Fine-Sediment Loadings to Lake Tahoe. Journal of the American Water Resources Association, 44(3): 618-639.

Simon, A., Doyle, M., Kondolf, M., Shields Jr, F.D., Rhoads, B., Mcphillips, M. 2008. Reply to Discussion by Dave Rosgen of Critical Evaluation of How the Rosgen Classification and Associated "Natural Channel Design" Methods Fail to Integrate and Quantify Fluvial Processes and Channel Response?. Journal of the American Water Resources Association, 44(3): 793-802.

Lowrance, R.R., Isenhart, T.M., Gburek, W., Shields Jr, F.D., Wigington, Jr., P.J., Dabney, S.M. 2006. Environmental Benefits of Conservation on Cropland: The Status of Our Knwoledge. Landscape management. Ankeny, IA: Soil and Water Conservation Society. 326 p.

Wells, R.R., Langendoen, E.J., Simon, A. 2007. Modeling Pre- and Post-Dam Removal Sediment Dynamics: The Kalamazoo River, Michigan. Journal of the American Water Resources Association, 43(3): 773-785. DOI:10.1111/j.1752-1688.2007.00062.x

Gordon, L.M., Bennett, S.J., Alonso, C.V., Bingner, R.L. 2008. Modeling Long-Term Soil Losses on Agricultural Fields Due to Ephemeral Gully Erosion. Journal of Soil and Water Conservation, 63(4): 173-181.

Parker, C., Simon, A., Thorne, C. 2008. The Effects of Variability in Bank-Material Properties on Riverbank Stability: Goodwin Creek, Mississippi. Geomorphology, doi:10.1016/j.geomorph.2008.02.007.

Last Modified: 9/10/2014
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