Ideas Conservational Channel Evolution and Pollutant Transport System .


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Ideas – Conservational Channel Evolution and Pollutant Transport System Eddy J. Langendoen Robert E. Thomas USDA Agricultural Research Service National Sedimentation Laboratory Oxford, Mississippi

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Instructors Eddy Langendoen Research Hydraulic Engineer with USDA-ARS National Sedimentation Laboratory Developer of CONCEPTS Develop advances that incorporate fluvial hydrodynamics, sedimentation building, and PC displaying strategies to look at the adequacy of adjustment and rebuilding hones Background in computational power through pressure M.S. in Civil Engineering and Ph.D. from Delft University of Technology, The Netherlands

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Instructors (cont.) Rob Thomas Research Associate with USDA-ARS National Sedimentation Laboratory Investigating sidelong and vertical alteration of channels to unsettling influences, including observing and displaying of the upstream relocation of knickpoints. Utilization of CONCEPTS to Goodwin Creek and the Yalobusha River, Mississippi. B.S. in Geography from University of Nottingham, England

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Course Outline Introduction Why CONCEPTS? A use of CONCEPTS review Hydraulics Sediment transport and bed modification Streambank disintegration mechanics

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Course Outline (cont.) Input information Required information How would we get it? Yield information Output sorts Output choices Execution of CONCEPTS utilizing test applications Preparing input records Running CONCEPTS Viewing/translating yield documents

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Why Do We Use/Develop CONCEPTS? The greater part of our work is in the Mid-Continental USA Highly erodible soils Channelized stream frameworks Unstable stream frameworks How would we be able to decrease affect or balance out these stream frameworks

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Characteristics of Unstable Streams Migrating knickpoints Mass squandering of streambanks Recruitment of expansive woody flotsam and jetsam Impairment Stream Habitat Infrastructure

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Stream Rehabilitation/Restoration Stabilize stream "Hard" structures (solid, shake) "Delicate" bioengineered or vegetative arrangements Combination (Re)construct channel Does our outline work? Need to assess plan CONCEPTS

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Sample Application of CONCEPTS – Yalobusha River, Mississippi

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Yalobusha River – Background European agrarian advancement mid nineteenth century Channel limit confined by residue and flotsam and jetsam amassing Excavation of 12-mile jettison through the waterway\'s valley mid twentieth century Sand, sediment, and trash shut lower some portion of the direct Clearing in the 1940s New channelization in the 1960s Extending trench downstream Realigned and dug the mouths of all significant tributaries Construction of disintegration control structures

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Yalobusha River – Background (cont.) Channel reaction: Headward moving knickpoints in all tribs Extensive streambank disintegration Recruitment of substantial woody garbage Deposition of sands and trash at the end of channelization Flooding issues at Calhoun City Mitigation: plug evacuation

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Channel Evolution Channels react to: Hydrologic Changes in silt loadings Man-rolled out improvements How do channels modify? Vertically: scour – fill, corruption – aggradation Horizontally: augmenting & relocation Models must catch these procedures Hydraulics Sediment transport and bed alteration Streambank mechanics

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Output: Changes in channel geometry Time arrangement of pressure driven factors and dregs yield Input: Channel geometry Composition of informal lodging materials Erosion resistance and shear quality of overnight boardinghouse materials Rates of stream and residue entering the channel Bendway weir Bed advancement and silt transport Streambank disintegration Flow power through pressure CONCEPTS – CONservational Channel Evolution and Pollutant Transport System CONCEPTS reenacts long haul reaction of channels to loadings of water and dregs, and to instream structures

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Hydraulics

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Hydraulics Unsteady One-dimensional Long term recreations Cross-stream varieties are disregarded Gradually-shifting St. Venant conditions Special procedures to deal with "conspicuous" overflow occasions Solution technique Generalized Preissmann plot Gaussian disposal

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Hydraulics – Boundary Conditions Boundary conditions External limits Upstream and downstream closures of stream hall Internal limits Locations where the stream is quickly shifted Hydraulic structures Knickpoints Rapids

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Hydraulics – External Boundary Conditions Upstream limit Discharge hydrograph Downstream limit Rating bend User indicated CONCEPTS\' created circle rating bend h = stream profundity (m) K = movement (m 3/s) Q = stream release (m 3/s) S f = rubbing incline (m/m) t = time (s) a = coefficient of rating bend b = type of rating bend

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Hydraulics – Hydraulic Structures Hydraulic structures in CONCEPTS Box and pipe courses Bridge intersections Grade control structures Generic structures We require two conditions Continuity condition Dynamic condition Relate release with stages upstream and downstream of the structure

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Sediment Transport

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Sediment Transport Sediment transport rates are an element of: Flow power through pressure Bed arrangement Upstream dregs supply Sediment kept on or scoured from the bed changes bed organization, stream hydrodynamics, and partial transport rates Sediment release is in this manner figured utilizing a vehicle (shift in weather conditions) condition with source terms speaking to loadings (entrainment and horizontal commitments) and misfortunes (statement)

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Sediment Transport (cont.) Sediment blends 13 predefined measure classes Sediment transport limit is anticipated by SEDTRA CONCEPTS tracks the sythesis of both surface and substrate Distinguish diverse disintegration attributes of strong and cohesionless bed material Cohesionless: neighborhood disintegration or testimony is corresponding to the distinction between silt transport rate and limit Cohesive: abundance shear stretch approach

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Sediment Transport – Sediment Sizes and Transport Equations

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Sediment Transport – Approximation Fractional stride strategy. The vehicle condition is part into a comparable arrangement of: Advection condition Sediment mass is transported downstream without the impacts of sources and misfortunes. Understood by the strategy for attributes Rate-of-Change condition Sediment mass is balanced by considering disintegration and testimony Analytical arrangement expecting residue transport limit is steady amid a period step

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Sediment Transport – Bed Adjustment affidavit halfway wetted bed disintegration mostly wetted bed disintegration completely wetted bed statement completely wetted bed

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Sediment Transport – Boundary Conditions Upstream limit Sediment stack as a small amount of neighborhood silt transport limit Time arrangement of dregs load (kg/s) Downstream limit Not required by the arrangement technique, however just procedures happening in the achieve then decide the advancement of the outlet. Change in bed height can be balanced by duplicating it with a coefficient shifting in the vicinity of 0 and 1.

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Sediment Transport – Internal Boundary Conditions Sediment transport rate at a pressure driven structure is an element of the supply of dregs and the modify of the structure If reverse is above channel bed, particles transported as bed load are kept If transform is beneath or at the channel bed all residue passes the structure

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Streambank Erosion

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Streambank Erosion Channel-width modification happens in a wide assortment of geomorphic settings Equilibrium methodologies are probably not going to precisely foresee width conformity after some time Fundamental procedures in charge of bank withdraw Hydraulic disintegration Mass bank disappointment

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Streambank Erosion – Hydraulic Erosion Transport, statement, and disintegration of durable silt are amazingly mind boggling Erosion rate is given by an overabundance shear stretch connection Critical shear push: Arulanandan et al. (1980) if sodium adsorption proportion, dielectric scattering, and pore liquid salt focus are known In situ estimations (Hanson and Simon 2001) Historical information on the withdraw of the base of the bank consolidated with stream information The impacts of weathering procedures and vegetation can be incorporated by modifying basic shear push

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Streambank Erosion – Hydraulic Erosion (cont.) Average shear stretch t i on each dirt layer Average disintegration separate D E i

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Streambank Erosion – Rotational Streambank Failure

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Streambank Erosion – Planar Streambank Failure

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Streambank Erosion – Cantilever Streambank Failure

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Streambank Erosion – Piping Streambank Failure

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Streambank Erosion – Streambank Stability Weight is the essential drive tending to move the disappointment square Mobilized shear at the slip surface is the essential opposing power Shear quality is influenced by Pore-water weights Vegetation Mechanical fortification Reduction of soil dampness through overhang block attempt and evapotranspiration Increase soil dampness through stem stream

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Streambank Erosion – Planar Failure Analysis Stability is investigated utilizing limit balance techniques => FOS Methods are based upon static harmonies of powers and additionally minutes Method of cuts F w = keeping power (N/m) N = ordinary constrain (N/m) S = prepared shear compel (N/m) W = weight of composite soil (N/m) b = edge of slip surface

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Streambank Erosion – Inclination of Failure Surface The slant of the disappointment plane is that for which the element of security is a base CONCEPTS utilizes a pursuit strategy to discover littlest FOS Factor of wellbeing is assessed at N e number of focuses along the bank profile

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Test Cases

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Test Case 1 Prismatic channel 25 km long 0.002 m/m bed slant Manning n is 0.04 51 Cross segments made out of a rectangular principle channel right-overbank sectio

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