Problem 1 (5 points). The bottom slope of a long trapezoidal channel (bottom width = 15 ft, side slopes = 1:1) is suddenly changed from 0.0005 to 0.05. The flow in the channel is 800 ft³/sec and the Manning n is 0.028. Compute the critical and normal flow depths in each channel reach and sketch the water surface profile. Problem 2 (5 points). Sketch and label the type of water surface profiles in this channel: NDL CDL NDL Note that, in the last part, the channel bottom is horizontal. Problem 3 (15 points). (a) Sketch one of the possible water surface profiles for this channel: NDL CDL Reservoir Steep Mild Steep Reservoir (b) Compute the water surface profile using the standard step method in steady conditions for Q = 30 m³/s from Section 1 to Section 2 (see figure below), assuming: - Section: rectangular with bottom width of 10 m. 1 - Manning coefficient n = 0.013. - Length from Section 1 to Section 2 = 100 m. - Elevation of the channel bottom at Section 1: z1: - 100 m. - Elevation of water level at the upstream reservoir: z = 105 m. NDL CDL Reservoir So,1 = 0.01 Section 1 So,2 = 0.001 So,3 = 0.01 Section 2 Section 3 Reservoir Questions: Discuss the assumptions made to compute the water surface profile. Show how you applied the equation of the standard step method for the first computation, i.e. from (x1,y1) to the next value (x2, y2) (where x2 = x1 + Ax and Ax is the computational length interval of your choice). : and 2. Attach a graph with the water surface profile. Report the values of normal depth, critical depth, and water depth at sections 1 Additional Questions for Graduate students: (c) Based on the water profile sketched in point (a), you should be able to know the water depth at Section 3, which represents a “control section”. Through this information and knowing that the length from Section 2 to Section 3 is 500 m: - Find out whether a hydraulic jump will occur either in (i) the channel reach from Section 1 to Section 2, or (ii) the channel reach from Section 2 to Section 3. - What will happen if S0,2 = 0.0003? 2 Problem 4 (15 points; note that graduate students have an additional question). The HEC-RAS program has been developed by the U.S. Army Corps of Engineers (USACE). This software allows the user to perform one-dimensional steady flow, one and two-dimensional unsteady flow calculations, sediment transport/mobile bed computations, and water temperature/water quality modeling. The objective of this problem is to develop the HEC-RAS model for one-dimensional steady flow analysis for the case that we have seen in Lecture 8: 2 K b S₁ > Sc S2 < Sc S3 > S₁ > Sc Step 1 • Download and install the software at: https://www.hec.usace.army.mil/software/hec-ras/download.aspx You should get the “HEC-RAS 5.0.X Setup Package Documentation, and Example Data sets (525 MB)” in the "Archived Versions". You may download any version later than 5.0.3. ✓ Archived Versions: Download HEC-RAS 6.3 Setup Package (201 MB) [Release Notes] Download HEC-RAS 6.2 Setup Package (201 MB) [Release Notes] Download HEC-RAS 6.1 Setup Package and Documentation (336 MB) [Release Notes] Download HEC-RAS 6.0 Setup Package, Documentation, and Example Data sets (729 MB) [Release Notes] Download HEC-RAS 5.0.7 Setup Package Documentation, and Example Data sets (691 MB) [Release Notes] Download HEC-RAS 5.0.7 Setup Package and Documentation (385 MB) [Release Notes] Download HEC-RAS 5.0.6 Setup Package Documentation, and Example Data sets (659 MB) Download HEC-RAS 5.0.6 Setup Package and Documentation (358 MB) Download HEC-RAS 5.0.5 Setup Package Documentation, and Example Data sets (715 MB) Download HEC-RAS 5.0.5 Setup Package and Documentation (414 MB) Download HEC-RAS 5.0.4 Setup Package Documentation, and Example Data sets (715 MB) Download HEC-RAS 5.0.4 Setup Package and Documentation (414 MB) Download HEC-RAS 5.0.3 Setup Package Documentation, and Example Data sets (525 MB) Download HEC-RAS 5.0.3 Setup Package and Documentation (202 MB) • The procedure to install the software is straightforward and relatively fast. After you open the program, you should see the main window reported in Figure 1: 3 HEC-RAS 5.0.1 File Edit Run View Options GIS Tools Help SED Project: Plan: C(t) DSS ப ✗ Geometry: Steady Flow: Unsteady Flow: Description: Figure 1 • SI Units You can access the User Manual through the “Help” tab. It is very important that you consult the manual whenever you have doubts. Step 2 • • Select the SI unit systems from Options → Unit system. The “SI Units" label will appear in the lower right corner of the main window (see Figure 1). Create a new project from: File → New Project Save it in a folder that you should create for this problem. • Enter Title: Homework_3 The software will use the same name for File Name, adding the extension *.prj (see Figure 2) New Project Title Homework 3 OK Cancel Help File Name Homework_3.prj Selected Folder Default Project Folder Documents y:\didattica (CEE441_Water Resources_Engineering y:\ didattica CEE441_Water_Resources Engineering Class 2017 ExampleProblems Exams HEC_RAS Homework LectureNotes_Larry Notes Pictures References Slides Create Folder ... y: [\\vmware-host\Shared Folders\avoro] Set drive and path, then enter a new project title and file name. Figure 2 Step 3 4 Insert the geometric data from Edit → Geometric Data (Figure 3). HEC-RAS 5.0.1 File Edit Run View Options GIS Tools Help E Geometric Data ... Projec Steady Flow Data... Plan: Quasi Unsteady Flow (Sediment Analysis) ... Geom Unsteady Flow Data ... Stead Sediment Data ... Unste Water Quality Data... Descri DSS SI Units Figure 3 • A new window will appear. We will be interested in River Reach and Cross Section (red rectangles in Figure 4). Geometric Data File Edit Options ☐ ✗ View Tables Tools Tools River Reach Storage Area GIS Tools Help 2D Flow SA/2D Area SA/2D Area 2D Area 2D Area Area Conn BC Lines BreakLines Mann n Pump Station Description: Plot WS extents for Profile: Editors Regions (P RS 12.99 Junct. Cross Section Brdg/Culv Inline Structure Lateral Structure Storage Area 2D Flow Area SA/2D Area Conn Pump Station HTab Param. View Picture Figure 4 Step 3.1 Draw a reach by selecting the River Reach button (click once). ○ Instructions: Move over the screen to draw the reach. Define the reach proceeding from upstream to downstream. Click the mouse button once to start. 1.2990, 0.8000 5/n Problem 1 (25 points). In this homework assignment, you will use the software HEC-RAS to design the replacement of an existing culvert in order to avoid overtopping of the roadway for the 25-yr discharge. Graduate students will also perform analyses to generate the performance curve. The instructions of this assignment include: 1. From Chapter 6 of the “HEC-RAS Hydraulic Reference Manual", learn how culverts are modeled in this software: http://www.hec.usace.army.mil/software/hec-ras/documentation/HEC- RAS%205.0%20Reference%20Manual.pdf 2. From Chapter 6 of the "HEC-RAS User's Manual”, learn how geometric data for culverts (and bridges) are entered: http://www.hec.usace.army.mil/software/hec-ras/documentation/HEC- RAS%205.0%20Users%20Manual.pdf 3. When you installed HEC-RAS last time, you should have downloaded the examples datasets. If you did not do so, download the version with the examples: https://iwr-hec.s3.amazonaws.com/HEC-RAS_503_Setup.exe 4. We will use the example described in Chapter 3 of the “HEC-RAS Applications Guide": http://www.hec.usace.army.mil/software/hec-ras/documentation/HEC- RAS%205.0%20Applications%20Guide.pdf This example is called "Single Culvert (Multiple Identical Barrel)”. You should open HEC-RAS and load this example, which is located in the folder: "PATH WHERE YOU SAVED THE APPLICATIONS/HEC_RAS/Applications Guide/Chapter 3 - Single Culvert" After you open the example, inspect the Geometric Data, including river reach, location of the culvert, type of culvert, location of the four cross sections that are needed to perform culvert modeling in HEC-RAS. Details are explained in the chapters of the different manuals mentioned above. You will notice that the type of existing culvert is circular with two identical barrels, as shown in Figure 1. In the "Steady Flow Data”, three discharge values have been provided, corresponding to the 5-yr, 10-yr and 25-yr event. Run the simulation as suggested in the example and inspect the results in each case, including the water profile, the headwater 1 elevation, and the type of control. You will notice that, for the 25-yr discharge, the roadway is overtopped (Figure 2). Bridge Culvert Data - Multiple Pipe Geometry File View Options Help ☐ ✗ River: Spring Creek Apply Data Reach: Culvrt Reach River Sta.: 20.237 Description Twin Circular Pipe Crossing Bounding XS's: 20.238 20.227 Distance between: 57 (ft) Deck/ Roadway RS-20.237 Upstream (Culvert) 38: 36 Pier Ground Sloping Abutment Elevation (ft) 34: 32 HH Ineff Bank Sta Legend 30 Bridge Modeling Approach 850 900 950 1000 1050 1100 1150 Culvert RS-20.237 Downstream (Culvert) Multiple Opening Analysis HTab 36 34 Param. HTab Curves Elevation (ft) 30 28 26 Bridge Design 24+ 850 900 950 1000 1050 1100 1150 Station (ft) Select the river for Bridge/Culvert Editing Figure 1 2 Elevation (it) Profile Plot File Options Help Reaches 24 36 34 30- 28- ↓ Profiles Plot Initial Conditions Twin Circular Pipe - Example 3 Plan: Spring Creek Culverts Spring Creek Culvrt Reach 3/21/2017 22 0 500 1000 1500 2000 2500 3000 Main Channel Distance (ft) Figure 2 5. Your goal is to replace the existing culvert with a box culvert with a single barrel to avoid overtopping of the roadway for the 25-yr discharge. For this aim, you need first to save a copy of the Single Culvert Example in another folder using File Save As in the main window. This will be the copy that you can use to test different design options and perform your analyses. To replace the culvert, you need first to delete the existing one by clicking Delete in the Culvert Data Editor (Figure 3): 3 ☐ Reload Data Legend EG 25 yr WS 25 yr Crit 25 yr Ground HEC-RAS 5.0.1 Bridge Culvert Data - Multiple Pipe Geometry File View Options Help DSS River: Spring Creek Apply Data +10 Reach: Culvrt Reach River Sta.: 20.237 ↑ Description Twin Circular Pipe Crossing Bounding XS's: 20.238 20.227 Deck/ Roadway Distance between: 57 (ft) RS-20.237 Upstream (Culvert) uide \Chapter 3-Single Culvert\TWINPIPE.prj plications Guide\Chapter 3 - Single Culvert\TWINPIPE.p01 plications Guide\Chapter 3 - Single Culvert\TWINPIPE.901 plications Guide\Chapter 3 - Single Culvert\TWINPIPE.f01 387 US Customary Units 36 Pier 34 Sloping Abutment Elevation (ft) 32 Legend Ground Ineff Bank Sta Culvert Data Editor Add... Copy 30 Solution Criteria: Delete... Culvert ID Highest S. EG Circular Rename ... 28 Bridge Shape: Circular Span: Diameter: 6 [Modeling 263 Approach 24 850 900 950 1000 1050 1100 1150 Culvert Chart RS-20.237 Downstream (Culvert) 1-Concrete Pipe Culvert Scale #: 1-Square edge entrance with headwall Multiple Opening Analysis 36 HTab Param. HTab Curves Elevation (ft) 321 30 28 སྣ་་་་་ Distance to Upstrm XS: 5 Culvert Length: 50 26 Bridge Design 24 Entrance Loss Coeff: Exit Loss Coeff: Manning's n for Top: Manning's n for Bottom: Depth to use Bottom n: Depth Blocked: 0.5 Upstream Invert Elev: Downstream Invert ? #identical barrels : 25.1 1 0.013 ? 25 2 Centerline Stations Upstream Downstream 0.013 0 |0 -234 1996. 21004. 996. 1004. 850 900 950 1000 1050 1100 1150 OK Cancel Help Station (ft) 1133.64, 24.37 Select culvert to edit 21237 20.208* 20.189 Figure 3 Next, you will need to select a new culvert type. The section ID where the culvert is located will remain 20.237. For this assignment, you should select “Box” as Shape. You are free to choose the Chart and Scale # options. For the other parameters of the culvert, you should: (a) keep the same values of Distance to Upstrm XS, Culvert Length, Entrance Loss Coeff, Exit Loss Coeff, Upstream Invert Elev, and Downstream Invert that are used in the existing culvert; (b) modify the Manning's n values as appropriate based on your choice of culvert type and material; (c) indicate the Centerline Stations upstream and downstream of one barrel (you should go through the instructions to understand what these are); (d) select the size of the box culvert by modifying the Span and Rise. Since, in this assignment, we are not modifying the Ineffective Flow areas in the sections right upstream and downstream of the culvert, you need to set Span = 14 ft. The value of Rise is a design choice. Once you have replaced the culvert type, run the simulations and make sure that no overtopping conditions are verified. 4 ་ arc ཇ། ། 6. Graduate Students should also develop a performance curve for the new culvert crossing. Use at least other 5 discharge values in addition to the existing ones, including one that causes the water level to go over the roadway. Briefly report your design, including methodology, design results and summary. Use graphs and HEC-RAS outputs as needed. 5