DOCSLIB.ORG

Guide for Selecting Manning's Roughness Coefficients

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Guide for Selecting Manning's Roughness Coefficients GUIDE FOR SELECTING MANNING’S ROUGHNESS Turner-Fairbank Highway COEFFICIENTS FOR NATURAL CHANNELS Research Center 6300 Georgetown Pike AND FLOOD PLAINS McLean, Virginia 22101 Report No. 3 t u FHWA-TS-84-204 U.S. Department of Transportation Final Report April 1984 -1 HishrwaV AdministrWon Archived ‘This document is available to the U.S. public through the National Technical Information Service, Springfield, Virginia 2216 FOREWORD This Technology Sharing Report provides procedures for determining Manning's roughness coefficient for densely vegetated flood plains. The guidelines should be of interest to hydraulic and bridge engineers. Environmental specialists concerned with flood plains and wetlands may also find this report useful. The report was prepared by the United States Geological Survey, Water Resources Division, with technical guidance from the FHWA Office of Engineering and Highway Operations Research and Development. Sufficient copies of the publication are being distributed to provide a minimum of one copy to each FHWA region office, division office, and to each State highway agency. Additional copies of the report can be obtained from the National Technical Information Service, Springfield, Virginia 22161. DirectdrJ Office of / Director, Office of Engineering and Highway Implementation Operations R&D NOTICE This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. The contents of this report reflect the views of the contractor, who is responsible for the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policy of the Department of Transportation. This report does not constitute a standard, specification or regulation. The United States Government does not endorse products or manufacturers. Trade or manufacturer's names appear herein only because they are considered essential to Archivedthe object of this document. Technical Report Documentation Page 1. Report No. 2. G overnment Accession No. 3. Recipient’s Catalog No. 'FHWA-TS-84-204 I I 4. Title and Subtitle 5. Report Dote GUIDE FOR SELECTING MANNING'S ROUGHNESS COEFFICIENTS . April 1984 FOR NATURAL CHANNELS AND FLOOD PLAINS 6. Performing Organization Code 8. Performing Organization Report No. 7. Author’s) G. J. Arcement, Jr., and V. R. Schneider 9. Performing Organization Name and Address 10. Work Unit NO. (TRAIS) U. S. Geological Survey Water Resources Division 11. Contract or Grant No. P.O. Box 66492 13. TYPO of Report and Period Covered Baton Rouge, LA 70896 9 12. Sponsoring Agency Name and Address Office of Implementation Final Report Federal Highway Administration 6300 Georgetown Pike 14. Sponsoring Agency Code McLean, Virginia 22101 15. s upplementory Notes Co-COTR: John M. Kurdziel Roy Trent 16. Abstract Although much research has been done on Manning's roughness coefficients for stream channels, very little has been done on the selection of roughness values for densely vegetated flood plains. A procedure for the determination of Manning's roughness coefficient (n) for channels and flood plains analyzes the different roughness factors that affect the roughness coefficients for channels and flood plains. By determining the value of each factor and combining those values, the n value can be determined. Another procedure deals with densely vegetated flood plains where the major roughness is caused by trees, vines, and brush. The n value for this type of flood plain can be determined by measuring the "vegetation density" of the flood plain. Photographs of flood plain segments where n values have been verified are presented as a comparison standard to aid in assigning n values to similar flood plains. 17. Key Words Archived18. Distributiov Statement Roughness Coefficient, Manning Equation, No restrictions. This document is Channels, Stable, Unstable, Channel Flow, available to the public through the Flood Plains, Flow Resistance, Hydraulic National Technical Information Service, Roughness, Hydraulic Friction, Overland Springfield, Virginia 22161. Flow, Vegetation Effects 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Prtce Unclassified Unclassified 68 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized Page Introduction------------------------------------------------------- 1 Approach--- ------- _________________-------------------------------- 2 Method for assigning n values for channels------------------------- 3 Selection of base n values (nb)------------------------------- 4 Adjustment factors for channels- ----------------------~~~~~~~- 8 Irregularity (nl)---------------------------------------- 8 Variation in channel cross section (n2)------------------ 8 (&stru&ions (n3)---------------------------------------- 12 Vegetation (n4) ____-------------------------------------- 12 Meandering (m) ---------------------~~~~~~~-~~~-----~---~~ 13 Methods for assigning n values for flood plains-------------------- 13 Modified channel method--------------------------------------- 13 Adjustment factors for flood plains---------------------- 16 Surface irregularities (nl)------------------------- 16 &structions (n3)----------------------------------- 16 Vegetation (n4)---------------------------------------- 16 Vegetation density methods------------------------------------ 17 Techniques for determining vegetation density------------ 17 Indirect technique---------------------------------- 18 Direct technique------------------------------------ 18 Pho+-ogra@s of flood plains---------------------------------------- 23 procedures for assigning n values---------------------------------- 39 Description of steps for assigning n values------------------- 39 Channel roughness (steps 3-13)--------------------------- 39 Flood-plain roughness (steps 14-23)---------------------- 50 Examples of procedures for determining n values---------- 51 60 &lw+-& references------------------------------------------------ 61 Archived ii LIST OF FIGURES Page Figure 1. Graph showing relation of stream power and median grain size to flow regime----------------------------- 6 2. Forms of bed roughness in sand-bed channels------------- 7 3. Plot of effective-drag coefficient versus hydraulic radius for wide, wooded flood plains using verified n values---------------------------------------------- 19 4. Example measurement of vegetation density of repre- sentative sample area--------------------------------- 21 5. Example of determination of Manning's n by direct technique of vegetation density----------------------- 22 6-20. Photograph showing flood plains having verified n values: 6. Cypress Creek near Downsville, La., n=O.lO------- 24 7. Bayou de Ioutre near Farmerville, La., n=O.ll---- 25 8. Bayou de Iioutre near Farmerville, La., n=O.ll---- 26 9. Bayou de Loutre near Farmerville, La., n=O.ll---- 27 10 . Coldwater River near Red Banks, Miss., n=O.ll---- 28 11. Coldwater River near Red Banks, Miss., n=O.ll---- 29 12. Yockanookany River near Thomastown, Miss., n=O.l2----------------------------------------- 30 13. Yockanookany River near Thomastown, Miss., n=O.12 ----------------------------------------- 31 14. Flagon Bayou near Libuse, La., n=0.13----------- 32 15. Pea Creek near Louisville, Ala., n=0.14---------- 33 16. Pea Creek near Louisville, Ala., n=O.14---------- 34 17. Tenmile Creek near Elizabeth, La., n=0.15-------- 35 18. Sixmile Creek near Sugartown, La., n=O.18-------- 36 19. Thompson Creek near Clara, Miss., n=O.20--------- 37 20. Thompson Creek near Clara, Miss., n=0.20--------- 38 21. Flow chart of procedures for assigning n values--------- 40 22. Sample form for computing n values---------------------- 42 23. Sketch of a hypothetical cross section showing reaches, segments, and subsections used in assigning n values-- 47 LIST OF TABLES Table 1. &se values of Manning's n------------------------------ 4 2. Factors that affect roughness of the channel------------ 9 3. Factors that affect roughness of flood plains----------- 14 4. Cutline and example of procedures for determining n valuesArchived for a hypothetical channel and flood plain----- 52 iii SYMBOLSANDUNITS svmbol Definition Units A cross-section area of flow ft2 CAi the total frontal area of vegetation blocking the flow ft2 c* effective drag coefficient for vegetation ----- d84 particle diameter that equals or exceeds that of 84 percent of the particles ft gravitational constant ft/s2 height of water on flood plain ft conveyance of a section ft3/s length of channel reach being considered ft length of representative sample area ft m correction factor for meandering of channel or flood plain ----- n Manning's roughness coefficient, including boundary and vegetation effects ftl/6 "b base value of Manning's roughness coefficient for the surface material of the channel or flood plain ftl/6 Cnidi summation of number of trees in a sample area multiplied by diameter ft “0 Manning's roughness coefficient, excluding the effect of the vegetation ft1/6 "1 value of Manniq's roughness coefficient for the effect of surface irregularity ftV6 "2 value of Manning's roughness coefficient for variations in shape and size of channel and flood plain ft1/6 n3 value of Manning's roughness coefficient for obstruc- ftl/6 tions "4 Archivedvalue of Manning's roughness coefficient for vegetation ftl/6 "4' value of Manning's roughness coefficient used in determining no, representing
Load more

Recommended publications
  • Properties and Definitions
    Properties and Definitions Useful constants, properties, and conversions 2 2 gc = 32.2 ft/sec [lbm-ft/lbf-sec ] 3 ρwater = 1.96 slugs/ft 3 γwater = 62.4 lb/ft 1 ft3/sec = 449 gpm 1 mgd = 1.547 ft3/sec 1 foot of water = 0.433 psi 1 psi = 2.31 ft of water Definitions discharge: flow rate, usually in ft3/sec or gpm Properties Density Density (ρ) is mass per unit volume (slugs/ft3) Specific Weight (aka Unit Weight) Specific Weight (γ) is weight per unit volume (lb/ft3) = ρg Specific Gravity Specific Gravity (S) is the ratio of the weight (or mass) or a substance to the weight (or mass) of water. where the subscript "s" denotes of a given substance and the subscript "w" denotes of water. Given S of a substance, you can easily calculate ρ and γ using the equations Specific Volume Specific Volume is the volume per unit mass (usually in ft3/lbm) Viscosity Viscosity (υ) is a measure of a fluid's ability to resist shearing force (usually in 2 lbf·sec/ft ) υ is a proportionality constant and is also known as absolute viscosity or dynamic viscosity. Viscosity is often given in the SI unit of Poise. To convert to English units use the relationship Kinematic Viscosity where γ = kinematic viscosity (ft2/s) 2 υ = dynamic viscosity (lbf·sec/ft ) ρ = mass density (slugs/ft3) Note: See CERM Appendix 14.A (page A-13) for a listing of water properties at various temperatures. Absolute and Gauge Pressure Absolute Pressure (psia) = Atmospheric Pressure + Gauge Pressure (psig) Atmospheric Pressure changes with weather conditions and altitude though is usually assumed to be 14.7 psi at sea level.
    [Show full text]
  • Hydropower Engineering Ii Lecture Note Compiled By
    Arbaminch University, Department of Hydraulic Eng’g HYDROPOWER ENGINEERING II LECTURE NOTE COMPILED BY: YONAS GEBRETSADIK LECTURER IN HYDRAULIC ENGINEERING DEPARTMENT OF HYDRAULIC ENGINEERING ARBA MINCH WATER TECHNOLOGY INSTITUTE ARBA MINCH UNIVERSITY JANUARY 2011 Hydropower Engineering-II Lecture Note/2010/2011 1 Arbaminch University, Department of Hydraulic Eng’g TABLE OF CONTENTS 1. HYDRAULIC TURBINES ............................................................................................................................. 5 1.1 GENERAL ............................................................................................................................................. 5 1.2 CLASSIFICATION .................................................................................................................................. 5 1.3 CHARACTERISTICS OF TURBINES ......................................................................................................... 6 1.4 PROCEDURE IN PRELIMINARY SELECTION OF TURBINES ...................................................................... 7 1.5 TURBINE SCROLL CASE ....................................................................................................................... 9 1.6 DRAFT TUBES .................................................................................................................................... 10 1.7 CAVITATION IN TURBINE & TURBINE SETTING ................................................................................. 11 1.8 GENERATORS AND TURBINE
    [Show full text]
  • Innovative and Low Cost Technologies Utilized in Sewerage
    ENVIRONMENTAL HEALTH PROGRAM INNOVATIVE AND LOW COST TECHNOLOGIES UTILIZED IN SEWERAGE TECHNICAL SERIES No. 29 PAN AMERICAN H EAU H ORGANIZATION Pan American Sanitary Bureau, Regional Office of the WORLD HhALTH ORGANIZATION ENVIRONMENTAL HEALTH PROGRAM u, •:'< i .:••;: .•: a. ! 4 INNOVATIVE AND LOW COST TECHNOLOGIES UTILIZED IN SEWERAGE AUTHOR José M. Azevedo Netto EDITED Raymond Reid WASHINGTON, D.C., MARCH 1992 PROLOGUE This publication is the product of the last contract of the late Jose Martiniano de Azevedo Netto with the Pan American Health Organization and is a significant example of a relationship of more than 40 years duration —a relationship that was characterized always with a touch of daring, and clever, innovative approaches to the solution of environmental health problems and risks. The contribution of Azevedo Netto to sanitary engineering goes far beyond his countless books, papers and articles. Thousands of public health and sanitary engineering professionals in Latin America have been affected and influenced by his inspiring and dedicated teachings and instruction. Azevedo Netto was born in Brazil in 1918, graduated as a civil engineer from the University of Sao Paulo, and earned his masters degree in sanitary engineering from Harvard University and his doctorate in public health from the University of Sao Paulo. The professional life of Professor Azevedo Netto, as he liked to be called, took him to all continents as a teacher and as technical advisor to governments and institutions such as Pan American Health Organization, the World Bank, Inter- American Development Bank and others. A founding member of the Inter-American and the Brazilian Associations of Sanitary and Environmental Engineering, Azevedo Netto raised the consciousness of the importance of sanitary engineering to improvement of peoples' health and quality of life.
    [Show full text]
  • Oft/Milar/ON in SEWER. DESIGN Flold Cjjflr.T
    · COST EFFECTIVENESS IN SEWER DESIGN by Gary J. Diorio, P.E. SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS for the Degree of Master of Science in the Civil Engineering Program ~{).~. ADVISER DATE DEAN of the Graduate School DATE Youngstown State University December, 1986 COST EFFECTIVENESS IN SEWER DESIGN © 1986 GARY J. DIORIO, P.E. All Rights Reserved i ABSTRACT COST EFFECTIVENESS IN SEWER DESIGN GARY J. DIORIO, P.E. MASTER OF SCIENCE YOUNGSTOWN STATE UNIVERSITY Probably the most important challenge facing an engineer today is to ensure that his design is competitive in terms of costs. Besides being technically sound, the designer's objectives are to provide a cost effective solution. This thesis presents a computer program to be used as a guide for the design of storm sewers to ensure a cost effective solution. The computer program is compiled to generate overland flows to inlets by use of a combination of the Rational Method and the Soil Conservation Method. The cost effective solution is found by applying the cost function according to the constraints set forth in the program. The program ~ constraints involve minimum slopes to ensure proper velocities in the pipe, proper pipe sizes to ensure a technically sound design, and to provide a minimum depth of sewer throughout the entire length. A case study is also included and analyzed to provide reliability data for the computer program. The design process, including cost computation, is laborious to the extent that it discourages the effort to explore all situations to arrive at a cost effective design. The purpose of this thesis is to provide the designer with the following: ii 1.
    [Show full text]
  • Calculating Resistance to Flow in Open Channels 1. Introduction
    Alternative Hydraulics Paper 2, 5 April 2010 Calculating resistance to flow in open channels John D. Fenton http://johndfenton.com/Alternative-Hydraulics.html [email protected] Abstract The Darcy-Weisbach formulation of flow resistance has advantages over the Gauckler-Manning- Strickler form. It is more fundamental, and research results for it should be able to be used in practice. A formula for the dimensionless resistance coefficient was presented by Yen (1991, equa- tion 30), which bridges between the limits of smooth flow and fully rough flow, to give a general formula for calculating resistance as a function of relative roughness and Reynolds number, appli- cable for a channel Reynolds number R>30 000 and relative roughness ε<0.05. In this paper, the author shows how a closely similar formula was obtained which is in terms of natural loga- rithms, which are simpler if further operations such as differentiation have to be performed. The formulae are shown to agree with predictions from the Gauckler-Manning-Strickler form, and with a modified form for open channels, have advantages that the equations are simpler and terms are more physically-obvious, as well as using dimensionless coefficients with a greater connectedness to other fluid mechanics studies. 1. Introduction The ASCE Task Force on Friction Factors in Open Channels (1963) expressed its belief in the general utility of using the Darcy-Weisbach formulation for resistance to flow in open channels, noting that it was more fundamental, and was based on more fundamental research. The
    [Show full text]
  • PDF, Bottom Friction Models for Shallow Water Equations: Manning's
    Journal of Physics: Conference Series PAPER • OPEN ACCESS Related content - Model reduction of unstable systems using Bottom friction models for shallow water balanced truncation method and its application to shallow water equations Kiki Mustaqim, Didik Khusnul Arif, Erna equations: Manning’s roughness coefficient and Apriliani et al. small-scale bottom heterogeneity - An averaging method for the weakly unstable shallow water equations in a flat inclined channel To cite this article: Tatyana Dyakonova and Alexander Khoperskov 2018 J. Phys.: Conf. Ser. 973 Richard Spindler 012032 - Computational multicore on two-layer 1D shallow water equations for erodible dambreak C A Simanjuntak, B A R H Bagustara and P H Gunawan View the article online for updates and enhancements. Recent citations - Numerical hydrodynamic model of the Lower Volga A Yu Klikunova and A V Khoperskov - Flow resistance in a variable cross section channel within the numerical model of shallow water T Dyakonova and A Khoperskov This content was downloaded from IP address 170.106.35.234 on 23/09/2021 at 14:15 AMSCM IOP Publishing IOP Conf. Series: Journal of Physics: Conf. Series1234567890 973 (2018) ‘’“” 012032 doi :10.1088/1742-6596/973/1/012032 Bottom friction models for shallow water equations: Manning's roughness coefficient and small-scale bottom heterogeneity Tatyana Dyakonova, Alexander Khoperskov Volgograd State University, Department of Information Systems and Computer Simulation, Volgograd, 400062, Russia E-mail: [email protected] Abstract. The correct description of the surface water dynamics in the model of shallow water requires accounting for friction. To simulate a channel flow in the Chezy model the constant Manning roughness coefficient is frequently used.
    [Show full text]
  • Sediment Transport in Open Channel Flows
    Introduction to Sediment Transport in Open Channel Flows Image source: http://earthsci.org/processes/geopro/stream/stream.html Arturo S. Leon, Ph.D., P.E., D.WRE Movies Scour at bridge model pier https://www.youtube.com/watch?v=48S_k6qAmsY&feature=emb_logo Utah Flash Flood https://www.youtube.com/watch?v=mXlr_Bgb-s0 Santa Clara Pueblo Flash Flood https://www.youtube.com/watch?v=nKOQzkRi4BQ Sediment Transport ● We study sediment transport to predict the risks of scouring of bridges, to estimate the siltation of a reservoir, etc. ● Most, if not all, natural channels have mobile beds ● Most mobile beds are in dynamic equilibrium: on average: sediment in = sediment out ● This dynamic equilibrium can be disturbed by . short-term extreme events (e.g., flash floods) . man-made infrastructure (e.g., dams) Source: https://www.flow3d.com/modeling-capabilities/sediment-transport-model/ Sediment Transport Fundamental Questions: ● Does sediment transport occur? (Threshold of motion). ● If so, then at what rate? (Sediment load) ● What net effect does it have on the bed? (Scour/accretion) The main types of sediment load (volume of sediment per unit of time) are Bed load and Suspended load. The sum is total load z = h Velocity Concentration Profile Profile Suspended z = z load ref Bed load Bed form motion: Dune Antidune Source: Lecture notes on Hydraulic, David Apsley Bed form motion (Cont.) Dune Antidune Source: https://armfield.co.uk/product/s8-mkii-sediment-transport-demonstration-channel/ Relevant Properties ● Particle ● Flow ‐Diameter, ‐Bed shear
    [Show full text]
  • Comparing the Calculation Method of the Manning Roughness Coefficient in Open Channels
    International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 4 Issue 06, June-2015 Comparing the Calculation Method of the Manning Roughness Coefficient in Open Channels Hari Wibowo 2 2 1Student of Doktoral Program on University of Suripin , Robert Kodoatie , 2 Diponegoro, Civil Engineering Department, University of Diponegoro 50241Semarang, Central Java,Indonesia 1 Water Resources Engineering Department, 50241Semarang University of Tanjungpura, 78115 Pontianak, West Borneo, Indonesia Isdiyana3 3RiverBalai, Water ResourcesResearchCenter , Balitbang the Ministry ofPublic Works Abstract—In hydraulic engineering, Manning roughness Philippe Gauckler in 1867, and then re-developed by the coefficient is an important parameter in designing hydraulic Irlandia engineer Robert Manning in 1890 (Bahramifar et al., structures and simulation models. This equation is applied to 2013). both uniform open channel flow, which is used to calculate the The study of the roughness coefficient has been much average flow velocity. The procedure for selecting the value of Manning n is subjective and requires assessment and skills research done previously, including Cowan (1956) which developed primarily through experience. examines pengenai hydraulic calculations, the roughness ManyempiricalformulaMenningthat was developedin order coefficient andAgricutural Engineering. Arcement and toobtainthe valuekoefsieinManning roughness. Fromseveral Schneider (1984) make modifications to the formulation studiesincludingthe formulationCowan(1956),
    [Show full text]
  • Steady Flow Analysis of Pipe Networks: an Instructional Manual
    Utah State University DigitalCommons@USU Reports Utah Water Research Laboratory January 1974 Steady Flow Analysis of Pipe Networks: An Instructional Manual Roland W. Jeppson Follow this and additional works at: https://digitalcommons.usu.edu/water_rep Part of the Civil and Environmental Engineering Commons, and the Water Resource Management Commons Recommended Citation Jeppson, Roland W., "Steady Flow Analysis of Pipe Networks: An Instructional Manual" (1974). Reports. Paper 300. https://digitalcommons.usu.edu/water_rep/300 This Report is brought to you for free and open access by the Utah Water Research Laboratory at DigitalCommons@USU. It has been accepted for inclusion in Reports by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. STEADY FLOW ANALYSIS OF PIPE NETWORKS­ An Instructional Manual by Roland W. Jeppson Developed with support from the Quality of Rural Life Program funded by the Kellogg Foundation and Utah State University Copyright ® 1974 by Roland W. Jeppson This manual, or parts thereof, may not be reproduced in any form without permission of the author. Department of Civil and Environmental Engineering and Utah Water Research Laboratory Utah State University Logan. Utah 84322 $6.50 September 1974 TABLE OF CONTENTS Chapter Page FUNDAMENTALS OF FLUID MECHANICS Introduction . Fluid Properties Density. I Specific weight I Viscosity 1 Example Problems Dealing with Fluid Properties 2 Conservation Laws 3 In trodu cti on 3 Continuity. 3 Example Problems Applying Continuity 4 Conservation of Energy (Bernoulli Equation) 6 Example Problems Dealing with Conservation Laws 9 Momentum Principle in Fluid Mechanics 12 II FRICTIONAL HEAD LOSSES 13 Introduction . 13 Darcy-Weisbach Equation.
    [Show full text]
  • 5.2.4 Open Channels Gate Is Operated by Raising Or Lowering to Allow Water to Pass Beneath the Gate Plate
    128 Laymans Guidebook Chapter 5. Hydraulic structures 129 Photo 5.17 Photo 5.19 Globe and rotary valves (figure 5.28) have lower head losses than the slide and load. Because the hydrostatic load passes through the trunnions, the lifting force butterfly gate valves and are also commonly used in spite of their higher price. required by the hoisting mechanism is minimised. The head losses in gates and valves are relatively high, especially when are operated as regulating devices. The radial gates (figure 5.29), conceptually different, are a method of forming a For further details refer to Chapter 2, Section 2.2.4 and the enclosed bibliography. moveable overflow crest and allow a close control of headwater and tailwater. In photo 5.19 it can be seen the housing of the sector on a concrete pier. The radial 5.2.4 Open channels gate is operated by raising or lowering to allow water to pass beneath the gate plate. The curved plate that forms the upstream face is concentric with the trunnions 5.2.4.1 Design and dimensioning of the gate. The trunnions are anchored in the piers and carry the full hydrostatic The flow conveyed by a canal is a function of its cross-sectional profile, its slope, and its roughness. Natural channels are normally very irregular in shape, and their surface roughness changes with distance and time. The application of hydraulic theory to natural channels is more complex than for artificial channels where the cross-section is regular in shape and the surface roughness of the construction materials - earth, concrete, steel or wood - is well documented, so that the application of hydraulic theories yields reasonably accurate results.
    [Show full text]
  • FDM 13-30 Channels and Road Ditches
    Facilities Development Manual Wisconsin Department of Transportation Chapter 13 Drainage Section 30 Channels and Road Ditches FDM 13-30-1 Channel Types and Characteristics October 22, 2012 1.1 Channel Types Roadside drainage channels perform the vital functions of collecting surface water runoff from the highway and carrying it to natural channels, providing snow storage and filtering sediment from runoff. They should provide the most efficient, stable, and effective disposal system for highway surface runoff, consistent with cost, importance of the road, economy of maintenance, and legal requirements. A standard drainage channel rarely provides the most satisfactory drainage for all sections of the highway, although it is the most efficient for most locations. 1.2 Roadside Ditches Side ditches are provided in cut sections to remove runoff from cut slopes, pavement, and adjacent areas draining into the highway right-of-way. Side ditches typically are triangular in cross section and dimensioned in accordance with appropriate design standards. The depth may be varied to keep a desirable minimum longitudinal slope of 0.5 percent and to keep the runoff from the design year storm below the top of the highway subgrade (refer to FDM13-10 Attachment 1.1). The minimum depth of a ditch is 1 ft below the subgrade shoulder point to ensure positive drainage of the subgrade. Refer to FDM11-15-1 for cross section elements for rural highways and freeways. 1.3 Median Ditches The shape, slope, bottom width, and gradient of a median may be varied as required to suit conditions. The following median geometrics are given in Chapter 11: 1.
    [Show full text]
  • Automatic Control Valve Using Servo Motor
    AUTOMATIC CONTROL VALVE USING SERVO MOTOR ZUL FADLI BIN MOHAMAD TOHID Report submitted in partial fulfilment of the requirements for the award of Bachelor of Mechanical Engineering Faculty of Mechanical Engineering UNIVERSITI MALAYSIA PAHANG JUNE 2013 vi ABSTRACT This thesis is about developing a small scale control system to control the flow rate of water by using a servo control valve. Arduino board as the microcontroller was used to make a control plant much easier. The simplify C/C++ programming language also is use to make control system coding. A servo motor with known characteristic in controlling the position with high accuracy and timing has been chosen to implement as a control valve in order to reduce error. This project originally is the flume project.A control valve controls the flow and velocity of water to maintain laminar flow before entering the flume. By accurate valve opening using servo motor and interface of Arduino programming language It is possible to develop a better control system in a large scale project on the future. The theory have been proved as the larger valve opening results in larger flow rate value. Based on the result, these small scale control flow system are capable to gradually reduce cost especially in control valve. The result also shows that using Arduino microcontroller a friendly-users control system efficiently. vii ABSTRAK Tesis ini membentangkan berkenaan pembikinan sistem kawalan skala kecil yang bertujuan mengawal aliran air dengan menggunakan injap yang dikawal oleh motor servo. Dengan menggunakan papan Arduino sebagai microcontroller, secara tidak langsung, langkah-langkah membina system kawalan menjadi lebih mudah.
    [Show full text]