Culvert Sizing Calculator

Culvert Sizing CalculatorOne-hundred year recurrence interval peak discharges are estimated, and wood passage concerns are addressed by sizing the culvert to fit the active channel width. Bearing Capacity - The maximum load that can be applied to a soil at the respective limit state. Used to calculate the velocity of water in a pipe. There are three (3) types of outlet control culvert flow conditions: 1. Minimum Cover Requirements · Pipe Storage Capacity . Drainage Calculator by Pipe Size. Calculation forms are provided for most of the design methodologies in the manual. Size a concrete culvert pipe crossing under a county road for the following design conditions: Q = 35 cfs; maximum headwater elevation is 104. In all culvert design, headwater or depth of ponding at the entrance to a culvert is an important factor in culvert capacity. In other words, as the Culvert approaches its flow capacity, it begins producing a headwater. Culvert and stream profile R O R 4. Determine the water velocity, and minimum pipe diameter based on flow rate and a 5 fps pipe velocity. You must determine, estimate, or calculate each factor as part of the hydraulic design or analysis. 2 x BFW) almost always results in headwater depths H w less than "just full" (H w/R o < 1) and thus hydraulic capacity generally is not an issue. The mass of the liquid is taken from the. An equation that relates culvert parameters for outlet control conditions in a pipe culvert design spreadsheet is: L = length of the culvert barrel (ft – U. Hydraulic Design of Highway Culverts. COMPUTATION OF PEAK DISCHARGE AT CULVERTS By RW. How do you size a drainage culvert? – MSI. A particular pipe size on a given grade will only carry a certain amount of water. An equation that relates culvert parameters for outlet control conditions in a pipe culvert design spreadsheet is: L = length of the culvert barrel (ft - U. The Prinsco Drainage Calculator estimates the capacity of tile drainage systems. The steeper the grade of the installed pipe, the more water it will carry. check upon the calculations involved in the preceeding columns. PDF Precast Concrete Box Culverts. Culvert Installation: All You Need to Know. This is the flow and depth inside the pipe. , 1967 Free on application to the Geological Survey, Washington 25, D. Precast Concrete Box Culvert Headwalls. Solve for part full pipe flows, or size a pipe with a known design flow. How To Calculate Culvert Pipe Size? – modeladvisor. of culvert flow as reported in the literature and on extensive laboratory, studies of culvert flow. PDF Computation of Peak Discharge at Culverts. resistance of culverts, and methods of optimizing culvert design using performance curves and inlet depression. The following materials/type are used in construction. Set same as floodplain slope Stream culvert sized To bankfull width. 6; upstream flowline elevation is 100. calculations according to Culvert Manual section 3. However, it is important to check the capacity, for two reasons: 1. Data 15, Hydraulic Sizing of Box Culverts. The calculation only functions for h/D≤0. 7; culvert length is 58 ft and the culvert will project from fill with no headwalls. The culvert size and type can be selected after the design discharge, controlling design headwater, slope, tailwater, and allowable outlet velocity have been determined. culvert size calculator for roads. The following form of the Manning equation for open channel flow under gravity, relates pipe culvert parameters under the condition of outlet control. Acres Drained: % Slope: Drainage Coefficient: 1 . Select parameter for solving, Velocity(V)&Discharge(Q) . calculations are conducted and it is determined that a 18” culvert would pass the design flow. Pipe Flow Wizard is a fluid flow rate and pressure loss calculator app from Pipe Flow Software. The parameters in the equation are as follows: HW is the headwater depth above the invert at the inlet in ft (m for S. PRELIMINARY BRIDGE DESIGN SOFTWARE. For circular pipes flowing full this can be . NEW: Water Pipe Size Calculator Information video WATER PIPE SIZE CALCULATORS Size every pipe in your project in seconds with just 3 clicks. Appendix 9: Talbot's Table for Round Culvert Sizing Based on Talbot's formula for a 2. Learn how to measure and calculate the best table size for your dining room. Box Culvert - A culvert in the shape of an enclosed rectangle and consisting of a bottom slab, two wall elements and a top slab. • After calculations, it was determined that a 9' x 7' box culvert will handle the required flow. Updated combo box size in the rational method calculator. circular-culvert-free-flow-discharge-calculation-lmno-eng image. CLIENT: DESIGNER: PROJECT: JOB NO: OUTFALL: DATE: 1 IN 10 YR:. Steps to calculate culvert lengths Step Do this… 1 Estimate the depth of fill (F) at the running surface on the inside of the road above the culvert inlet (point "a"). Type of culvert for first trial selection, including barrel cross sectional shape and entrance type. Pipe Water Velocity and Minimum Pipe Diameter. D is the inside height of the pipe culvert in fr (m for S. Culvert formula (Water Overlay). New culverts do not require a Type Size and Location plan (TSL. Having trouble finding a bra that fits? You’re not alone! Learn how a bra size fitting calculator can help. Given Data 10-year design flow= m^3/s Design Head Elevation, ELhd= m Road shoulder elev= Channel invert levation,Eli= Number of barrels Stream bed slope, So= m/m Approx Culvert length, La= Fall= Outlet elev, ELo= m S=So. Each class has specified wall and slab thicknesses, reinforcement areas, concrete strength, and fill height range to which it applies. evaluation of precast box culvert systems design live loads on box culverts contract no. 4) Bridge culvert Box culverts are low rise bridge or structure which is used 2. Proposed roadway details R O R 8. ini file must be customized to provide standard metric sizes. For culverts on steep forested wildlands, debris and sediment plugging cause culvert failure more frequently than peak flow capacity exceedance. For a pipe use its length instead of height: pipe volume = π * radius² * length, where radius = inner diameter/2. Culvert flowing "just full" or "100% full" at the inlet. To determine the right culvert size for your situation, you need to consider the dynamics of stream flow and how it changes with the seasons. Partially Full Pipe Flow Calculations. customary) units for all equations and design charts. Inlet control flow occurs when the flow capacity of the culvert entrance is less than the flow capacity of the culvert barrel. Figure 1 – Sizing of rock pad outlet structures for multi -pipe and box culvert outlets. You only need to know four of these five input variables. The following procedures assume steady flow but can involve extensive calculations that lend themselves to computer application. RATIONAL FORMULA AND COLEBROOK WHITE EQUATION. The type of control under which a particular box culvert operates is dependent on the location of the control section, which limits the maximum dis-charge through the culvert. To effectively design a river crossing, such as a culvert crossing, both the expected flood flow (design peak discharge) and the capacity for the stream . CHAPTER 5 DESIGN OF CULVERTS. culvert area is then calculated with the following equation: Required Culvert area (square feet) = H x (W 1 + W 2) Height: * W 12 + W = Culvert Area (square feet) Culvert area and corresponding round culvert size Culvert area (sq ft) Culvert diameter (in. Q = Discharge or flow rate through culvert [L3/T]. About Sizing Culvert Calculator. When selecting various inlet configurations, structural stability, aesthetics, erosion control, and fill retention should be considered. Unlike other calculators that measure flow rates, you are NOT confined to inputting diameter in inches, velocity in miles per hour and other factors, making . Round Culvert Sizing Calculator Using Talbot's Formula NOTE: The NC Forestry BMP Manual culvert sizing table uses 2. ) R = hydraulic radius of the full culvert barrel = A/P (ft - U. Select the appropriate capacity chart, Figures 42 to 145, for the culvert size approximately equal to the allowable headwater depth divided by 2. HDPEapp is an online tool developed for and released by the Plastics Pipe Institute (PPI). Objective being to avoid funneling over-bank flows. APPENDIX A: Culvert Sizing procedures for the 100. Appendix 9: Talbot’s Table for Round Culvert Sizing Based on Talbot's formula for a 2. Culvert length L [ft] m: Shoulder elevation E s [ft] m: Freeboard F b [ft] m: Entrance loss coefficient K e: Exit loss coefficient K E: OUTPUT: Please enter input data and press ‘Calculate‘, Your request was processed at 01:39:22 am on November 7th, 2021 [ 211107 01:39:22 ], Thank you for running. 01) R = hydraulic radius (cross sectional area of the fluid in the culvert divided by the wetted perimeter) H e)= entrance head loss =( 𝑉2 2 Equation 2E-2. The result comes to approximately 3 if multiplied by pi. 6, the live load patch for the design truck or tandem may be taken as the combination of both wheels for trucks or all four wheels for tandems for all fill heights. Select Channel Type: Trapezoid, Triangle, Rectangle, Circle. Outlet Control - Pipe Culvert Design Equations and Calculations. It will be helpful to you if you're, for example, designing an irrigation system for your garden. Hydraulic Design Series Number 5 - Hydraulic Design of Highway Culverts. buoyant forces and calculator calculates amount of gravity flow inlet in. Chart Shape Material Control Comments. Selecting Computational Methods. 20 Arch Metal Inlet Structural plate arch with inlet projecting,. 4, is the sum of the discharges Q 1 and Q 2. Re-development combined with information on site suitability, topography, and soil drainage determines whether complex, typical, or simple cost. Related Resources: excel calculators. This report aims to evaluate if the current method for sizing culverts is right for the application. This headwater begins to fill up . A fixed roadway crest elevation and length can be input or . The culvert size selection may vary slightly with differing landowner objectives, but the primary objective is to convey water beneath a road bed. Farmers choose polyethylene for its ruggedness in all temperatures, easy installation, low cost, and long service life. 5 hectares (common NZ catchment area size) 10 hectares (common NZ catchment area size) 15 hectares. The hydraulic design procedure for culverts requires: 1. For state structures, new culverts with clear spans greater than or equal to 6 ft. The total discharge at any point of the headwater elevation for culverts 1 and 2, on Figure 27. The Hydraulic Section will then provide the analysis necessary to determine the size and type of the proposed structure. A Mannings Formula pipe flow calculator for square and circular pipes. h =Measured water depth at end of channel (i. A prudent designer purposely will depress the road grade to allow for a storm-flow section equal to twice the cross-sectional area developed in Rule 2 to pass over the roadway. depth calculations using a software programme such as “Culvert”. Civil Engineering online calculation: Gravity-fed pipe flow - Hazen-Williams formula for a full pipe. Getting the flow into the pipe may require significantly higher headwater depth. 25 though it can be up to 3 to 5 if. Calculations are made for each potentially applicable condition; however, the discharge for the controlling condition is selected and indicated directly below the input section near the top of the Culvert Analysis sheet. peak flow calculated above and use Table 1, or Equation 2 or 3 if the culvert size does not appear in Table 1, to determine the size with a flow capacity . reduce the time consuming mathematical calculations. STORM WATER AND PIPE FLOW CALCULATOR. Determining the proper size (diameter) culvert requires. This causes the outflows from that device to route through the Culvert. Typically embedded so as to be surrounded by soil, a culvert may be made from a pipe, reinforced concrete or other material. The box will support HS20 loads: Use ASTM C 1433. Figure 2 – Typical layout of a rock pad for multiple pipe and box culverts (plan view) Table 1 – Minimum thickness (T) of rock pad. Culvert Sizing for Stream Crossings. Forest Practices Technical Note Number 5. Some culvert designs are relatively simple involving a straight-forward determination of culvert size and length. HDS 5 HYDRAULIC DESIGN OF HIGHWAY CULVERTS PDF. In addition, the influence of filling height, filling modulus, culvert size and subgrade modulus on the earth pressure concentration factor at culvert crown . Publication No FHWA-NHI-01-020, Revised May 2005. on numerous backwater calculations by the F. =𝐶 𝐴 2 𝑊−𝑦 HW = Head above the invert of the culvert y c = critical depth. TOKSTRIP SIZE 25mm x 40mm (unless otherwise specified by the concrete unit manufacturer) TOKSTRIP LENGTH (per joint) formula = 2 x height + 2 x width TOKSTRIP PRIMER 5 litres per 60m Tokstrip Size Guide for Box Culverts: A box culvert unit is lowered into position. Vertical distance divided by horizontal distance. PDF Box Culvert Length Calculator User Guide 1. Notes: This is the flow and depth inside the pipe. The “Flows through Culvert” option allows you to put structures in series, thereby creating a multi-stage structure. Headwater to culvert diameter (HW/D) should be less than or equal to 1. that can be used to determine the combined capacity of multiple culverts with different invert levels and capacities. GUIDELINES FOR DRAINAGE STUDIES AND HYDRAULIC DESIGN. Minimum Culvert Size 15 inches 15 inches 36 inches 1. This excel spreadsheet Culvert Design Calculates capacity of circular culverts based on culvert material, inlet type, diameter, and length. For example a 2400mm X 1200mm box culvert would be analyzed as a 8'X 4'. Inlet Control Nomograph for Pipe Culvert and Box Culvert The calculation of the partially full flow can be calculated by using Manning . Outlet control flow occurs when the culvert carrying capacity is limited by downstream conditions or by the flow capacity of the culvert barrel. require a Bridge Condition Report (BCR). Diameter Size: VFR Excess (Lit/min) No. This is described in the basic energy balance equation: Where: y = Depth (ft, m) V = Velocity (ft/s, m/s) D Z = Change in elevation (ft,m) TW = Tailwater. The formula for the volume of cylinder is: cylinder volume = π * radius² * height. profile calculation is the only way to accurately determine how much of the barrel flows full. In the fourth column, the number 1 is 1 2. For example, if the pipe has an internal diameter of 0. PDF General Permit Worksheet Culvert Placement on Navigable. the calculation is: SW = 2-foot culvert diameter. Inlet control: Unsubmerged entrance Inlet unsubmerged on steep slope with Weir Flow Rearranging the previous equation Circular culvert with squared edge Cd = 0. Calculations of outlet control incorporate the parameters from inlet control as well as the length and material of the culvert and the tailwater. These rules address pipe sizing, installation, pipe material, standard engineering calculations are to be completed because of the level . There are two major types of culvert flow conditions . Culvert Flow Calculator Free Recipes. Flow calculations handle pressure and varied flow situations such as . of Culverts Length (m) Total Cost. The purpose of this tool is to assist industry professionals in the evaluation and selection of HDPE pipe by performing design calculations documented in the PPI-Handbook of Polyethylene Pipe, 2nd Edition. The headwater depth (or headwater HW) is the vertical distance from the culvert invert at the entrance to the energy line of the headwater pool (depth + velocity head). Your request was processed at 03:39:05 am on March 31st, 2022 [ 220331 03:39:05 ]. Need help determining the size of your catchment area? Click here and use these maps. Hec05Table of Contents for HEC 5Hydraulic Charts for the Selection of Highway Culverts. The 25-year should allow 1 foot of freeboard for debris flow. The diameter of this pipe is 5 m. The sizing of the culvert crossing is for an average year storm. 2- Determining the size of the culvert which would handle that flow using the Federal Highway Administration (FHWA) culvert capacity nomograph (FHWA, 1965). Internal Dimensions (Based on flat invert culvert units). R = Culvert hydraulic radius of the flow cross-section [L]. A summary of selected methods, with example calculations for flood flow estimating is avail-able from the California Department of Forestry. of acres Impervious 100% runoff Steep slopes, heavy soils, moderate cover Moderate slopes, heavy to light soils, dense cover Gentle slopes, agricultural soils and cover Flatland pervious. These charts provide nomographs to determine inlet and outlet control headwater depths for common culvert shapes. culvert ends mitered to conform to the fill slope. · How many hectares is your catchment area?. When conveyance is high it may be necessary to install floodplain drainage or low areas across the road. You can use pressure drop calculator when the pressure difference between the start and the end of the pipeline (head loss) is available as a known value. Divide the diameter of the pipe by two. HW-Box Determines the headwater for a box culvert flow. All culvert, regardless of size, inherently have an associated risk of washout/failure. Pipe diameter and flow rate calculator, online. Units in circular culvert free-discharge water calculator: cm=centimeter, cfs=cubic foot . The controlling condition is also indicated. The type of control under which a particular box culvert operates is dependent on the location of the control section . Set same as thalweg riffle slope High floodplain conveyance affects design. Set the s direction parallel to the culvert and use Darcy's law (Eq. 2) K e = inlet loss coefficient (see Section 2E-1, Table 2E-1. Culvert Extension - A portion of a culvert built beyond the limits of a previously existing culvert. Culvert length and size R R R 5. Hydraulic Design Manual: Hydraulic Operation of Culverts. Culvert hydraulic capacity may be improved by selecting appropriate inlets. height (or size) of the orifice, the orifice equation provides results which . Sizing according to bankfull width (BFW) (BFW or 1. Culvert hydraulic and hydrology calculations R O R 2. I order to obtain an acceptable estimate of the culvert size, you should use more than one method and then choose the value that is "most reasonable". 5 sf (42” x 29”) Using HY-8 to Design Culverts Information you. Nomographs for additional culvert shapes are in FHWA Hydraulic Design Series No. The headwater submerges the culvert opening, and the culvert outlet is submerged by the tailwater. Hydraulic Modeling and Culvert Size Analysis. Any other use is at the sole discretion of the user. ) Culvert area (sq ft) Culvert diameter (in. A spreadsheet for making partially full pipe flow calculations is included with this course and its use is discussed and illustrated through worked examples. The hydraulic operation and performance of a culvert involve a number of factors. with local requirements and criteria for culvert sizing and road (see the Runoff chapter for information on hydrologic calculations). Performs civil engineering calculations for hydrology, open channels, culverts, gravity sewer, transmission lines and unit conversions. Units in circular culvert free-discharge water calculator: cm=centimeter, cfs=cubic foot per second, cms=cubic meter per second, ft=foot, gal=gallon (U. To determine headwater depth for a circular pipe. Each culvert size has three or four classes. Culverts are a common method to cross streams. A summary of selected methods, with example calculations for flood flow estimating is avail-. the resulting computed culvert capacity. Carter GEOLOGICAL SURVEY CIRCULAR 876 Washington, D. even if the calculations indicate that a smaller pipe is acceptable, . 6, the live load patch for the design truck or tandem may be taken as the combination of both wheels for trucks or all four wheels for. The second edition corrected minor errors and provided both SI and English (U. known or estimated prior to performing the culvert hydraulic calculations. online_culvert: Hydraulic design of highway culverts by FHWA method. This method of sizing culverts is taught in classes at the School of Forestry at the University of Canterbury and also used widely in industry. Fixed digital gradation dialog resizing issue. Where the size of an existing highway culvert is inadequate as a result of a acceptable to perform hydrograph calculations and routing. Culvert drainage design encompasses the selection of culvert materials, backfill requirements, scour protection, roadway alignment and adequate sizing to pass the expected flows. Input the average velocity of the flow. S = Slope of culvert bottom or water surface [L/L] . flood, and then 2) determining the size of culvert which would handle that flow using the Federal Highway Administration (FHWA) culvert capacity nomograph (FHWA, 1965). This calculator is a helpful tool for everyone who needs to know the exact volume of water in a pipe. Which means the culvert entrance is controlling the resulting headwater elevation for a given flow passing through the culvert. T = Top width of the flowing water in culvert [L]. • After calculations, it was determined that a 9’ x 7’ box culvert will handle the required flow. Note that h/D must be between 0. A culvert is a structure that allows water to flow under a road, railroad, trail, or similar obstruction. Head loss with Hagen-Poiseuille equation. Existing culverts with a clear span greater than or equal to 6 ft. The culvert will flow full (Condition A, Figure 7-3 in Appendix B of this Manual). culvert capacity nomograph (FHWA, 1965). Search: Culvert Size Calculator. Type of Culvert: ; Type of Culvert: · Discharge Q [cfs] (m3/ . 1; downstream flowline elevation is 99. Bottomless culverts with footings should be designed to pass the 100-year flow with the headwater less than the top of the culvert. The open channel flow calculator. y = Water depth in culvert measured normal (perpendicular) to the bottom of the culvert [L]. West Falmouth Harbor, West Falmouth, MA. Drainage Calculator, 1 2 3, Culvert design (slide rule format) . Flow through culverts is based on an open channel flow calculation. Use this calculator to compute the area that can be drained by a pipe of a given size and grade. ) the culvert was sized to pass the peak flows without overtopping the roadway. The diameter of pipe (s) used must add up to the total diameter needed without using a pipe taller than the average depth. The hydraulic calculations from the culvert outlet to the culvert headwater immediately upstream of the inlet are based on the conservation of energy and mass. The most recent version of the Drainage Manual is presented and is the official source for the development and application of all drainage design related to VDOT plans. Regardless of the changes made here, repeat the calculations and go back to step 2. Your request was processed at 12:00:12 pm on March 1st, 2022 [ 220301 12:00:12 ]. Selecting “Re-development” on the “Project Cost” tab of the National Stormwater Calculator influences the site complexity, and shifts the costs towards a higher complexity cost estimation. The culvert sizes used by the program for calculations are standard imperial sizes even when metric units have been chosen. Download Hydraulic Toolbox Version 5. Blockage, larger storms, rapid snowmelt, and debris flows all endanger the roadway and crossing. Q is the design discharge through the culvert in cfs (m3/s for S. It is necessary to break a pipe up into the appropriate diameter for the number of dimensions. HW-Pipe Determines the headwater for a circular pipe flow. Partially-full pipe flow calculation sheets solving for either flow (Q) or normal depth of flow (d) Riser Barrel Hydraulics with Coefficients. Online drainage calculator : UMN Extension. Inlet Control - Pipe Culvert Design Equations and Calculations The following equation that relates pipe culvert parameters under condition of inlet control comes from the U. g =Acceleration due to gravity=9. 5 for the discharge equation to be reliable. The tailwater must be known or estimated prior to performing the culvert hydraulic calculations. PDF HYDRAULICS OF CULVERTS. Culvert area and corresponding round culvert size Culvert area (sq ft) Culvert diameter (in. 97 inch) for the discharge equation to be. Culvert is a structure that provides the facility to cross the stream or chanal while allowing the water to flow through it. You can calculate the flow rate in five simple steps: Select the shape of the cross-section of the channel. 1,3,4,6: Calculator Design Series (CDS) 3 for TI-59, FHWA, 198O, page 16 3. 5) Arch culvert to discharge water in the proper channel in crossing of 3) According to the Classification by Loading as per railway, flyover, roads etc. Design for hydraulic efficiency overlooks the impact of a roadway-stream crossing on the stream-channel aquatic ecosystem…. Use the second form to calculate the inside. ) A = cross-sectional area of the culvert. WinTR-55 and Forest Service Peak Flow Calculator [19. 3 Culvert Sizing Using Hy-8 (version 7. Such performance curves are presented in Design. The calculator takes into account the roadway cross section, skew, vertical profile, and culvert properties to arrive at the barrel length required and the approximate. Culvert Design Excel Spreadsheet. Select your catchment area size and rainfall volume in the dropdown boxes. Use this calculator to compute the required pipe size for a given area and % grade. An accurate approximation to the rough diameter of a pipe is derived using the average depth multiplied by its average width and divided by four for determining how wide the pipes need be. How do you size a drainage culvert? We take the average depth multiplied by the average width to obtain the cross-sectional area and divide by four to determine the rough diameter of pipe needed to pass the average storm. Determining the proper size (diameter) culvert requires 1- Estimating the peak discharge of streamflow which would occur at each stream crossing during the 100-year flood, and then 2- Determining the size of the culvert which would handle that flow using the Federal Highway Administration (FHWA) culvert capacity nomograph (FHWA, 1965). Other designs are more complex where structural, hydraulic, environmental, or other considerations must be evaluated and provided for in the final design. Register to enable "Calculate" button. Circular culvert with squared edge Cd = 0. You can calculate your needed drainage pipe size by completing the three fields below and clicking "Calculate. Read this plain-English explanation to learn how culverts are used. SCDOT roadway drainage calculation support files. Roadway stationing at culvert R R R 3. • Box to be set at 8' depth, use table 1. 5 Cd can be corrected for bevels and rounding of the entrance Box culverts flush in vertical headwall Cd = 0. 2) Select Runoff Coefficient (c) = 0. Hobas is part of the Amiblu Group and is the specialist in storm- and wastewater, drinking water, irrigation, hydropower and industrial GRP pipe systems. Fixed issues with writing detention basin calculations to the report file. assembled to support the culvert design will be transferred to the TDOT Hydraulic Section. How Do You Calculate The Size Of A Culvert Pipe. Hydraulic Calculator Description. Examples displayed in the appendix apply the watercourse crossing sizing techniques to a small tributary basin located in the Caspar Creek watershed near Fort Bragg, California. 2 x BFW) almost always results in headwater depths H w less than “just full” (H w/R o < 1) and thus hydraulic capacity generally is not an issue. 14, Free surface (channel flow) calculations are approximate. individual culverts, compute the peak discharge generated over each culvert watershed for a range of storm events, and evaluate the hydraulic capacity of each culvert. Hydraulic Charts for The Selection of Highway Culverts. Key: Flow area m²/ Discharge rate m³/sec. 3) from the Federal Highway Administration and the site data (discharge, tailwater, roadway, etc. What size can be installed? Minimum of 24” . Bigger pipe is more expensive, but keeping the water velocity low is important to limit pressure losses due to friction, water hammer, and pipe movement due to water momentum changes inside the pipe. Search: Culvert Sizing Calculator. The open channel flow calculator Select Channel Type: Trapezoid Triangle Rectangle Circle Select parameter for solving Velocity(V)&Discharge(Q) Channel slope from V Channel slope from Q Manning Coefficient from V Manning Coefficient from Q Depth from Q RightSlope from Q Even slope from Q LeftSlope from Q. 5 times the velocity head to get the headwater depth or see my 2-minute tutorial for standard culvert headwater calculations using HY-8. The control section of a culvert .