Lab Exercise 5: Hydrologic modeling is used in practice today for environmental assessments, engineering design and water resources management. Computer-based models have replaced older methods, leading to a more automated planning/design process and generation of future scenarios. This fifth lab exercise is an introduction to the use of the Hydrologic Engineering Center- Hydrologic Modeling System (HEC-HMS) for runoff estimation in an urban area of Scottsdale, Arizona. We will be utilizing the geographical information system (GIS) layers obtained during our watershed delineation lab to setup and operate a lumped watershed model. As discussed in class, lumped models represent sub-basins as single units with uniform parameters. Our application is centered on eight sub-basins in the Scottsdale region of Indian Bend Wash. This lab exercise is novel in the sense that we will apply an existing hydrological modeling tool to an urban area within the Phoenix metropolitan region. This exercise primarily involves the study of extreme discharges on an urban basin using rainfall-runoff analysis. We could imagine that having such a model for each urban watershed in Phoenix would be an excellent tool for flood prediction in response to extreme storm events in the region. This lab is intended to be exploratory in nature and sufficiently rich for you to gain an understanding of how to setup HEC-HMS for another region. In addition, the various options for runoff generation and routing should reinforce theoretical concepts introduced in class. Consider this as practical implementation of the hydrologic science and engineering learned in class. The following pages will guide you through the setup and operation of HEC-HMS and its associated features as well as the manipulation of the relevant datasets provided to you for the exercise. The goal of the lab exercise is to complete the steps outlined below and submit the short questions listed on the last page. Discussions are encouraged, but each student should hand in their own answers. Remember to explore as you go along. 1. Obtaining HEC-HMS and Data Requirements HEC-HMS is a freely-available Windows program. We will utilize HEC-HMS version 4.5 obtained from the HEC's home page at: https://www.hec.usace.army.mil/software/hec- hms/downloads.aspx (click on achieved versions and select version 4.5 rather than use the newest as there is an error with shapefile visualization in version 4.6+). A user's manual is also available at this location. It is highly recommended to read the Quick Start Guide Manual for a better understanding of use of HEC-HMS model (http://www.hec.usace.army.mil/software/hec-hms/documentation.aspx). There are three ways you can access HEC-HMS: 1 1. Downloaded on your personal computer via the Army Corp site: https://www.hec.usace.army.mil/software/hec-hms/downloads.aspx 2. In the CAVC 533 computer lab, in person or via remote desktop (https://ets.engineering.asu.edu/it-support/computer-labs/). 3. Through the cloud desktop app Apporto accessed via the class Canvas site. See student guide to Apporto here: https://ets.engineering.asu.edu/fse-cloud- classroom/student-guide/ Speak to the TA as soon as possible if you do not have a computer on which you can install HEC-HMS or have trouble connecting to the virtual computing lab. HEC-HMS 3.5 Fin Eck View Components Parameters Compute Results Tools Help 1444 it OX Figure 1. HEC-HMS user interface after opening for the first time. To create a HEC-HMS model, a map file with the outline of the drainage areas and subbasins is useful for model construction. These files can be generated from a watershed delineation exercise (as in Lab 1). To help speed this process, these files for Scottsdale (zipped as Lab5Data.zip) can be downloaded from Canvas. Unzip the file and a working directory named Lab5Data will be created. Place the directory in a directory called HEC- HMS that is in an appropriate location (i.e., easy to remember and navigate to) for working with HEC-HMS. 2. Getting Started After installing HEC-HMS, start HEC-HMS by clicking on the HEC-HMS icon on the Desktop or by going to Start->Programs-> HEC-HMS->HEC-HMS 3.5. After a few seconds, the HEC- HMS User Interface shown in Figure 1 will appear. The HEC-HMS interface consists of a menu bar, tool bar, and four panes. These panes are referred to as the 2 Watershed Explorer, the Component Editor, the Message Log and the Desktop. Default Setting: Before creating a new project, it is recommended to set default parameters which will be used several times for each model element (subbasins, reaches, etc.). Select Tools-> Program Settings->Defaults. Modify the default settings to reflect the specifications in Figure 2. Note that we will use metric units and the following hydrologic equations: Initial and constant Loss, SCS Unit Hydrograph and Muskingum Routing. We will also use a Specified Hyetograph for the precipitation input. Explore the other options that exist within the HEC-HMS program to familiarize yourself with the broad number of potential applications. You should note many of the hydrological processes and estimation methods discussed in class. Program Settings General Basin Map Defaults Results Messages Unit system: Element sorting: Subbasin canopy: Subbasin surface: Subbasin loss: Subbasin transform: Subbasin baseflow: Reach routing: Metric Hydrologic --None-- --None-- Initial and Constant SCS Unit Hydrograph --None-- Muskingum Reach loss/gain: Subbasin precipitation: --None-- Specified Hyetograph Subbasin evapotranspiration: --None-- Subbasin snowmelt: |--None-- OK Cancel ✗ Figure 2. Default settings required for execution of Scottsdale model. Creating A New Project: The first step is to create a new HEC-HMS project by selecting File-> New in the menu bar. Enter the project name and description that you desire for the project (suggestions are provided below), and specify your working directory (the same directory that contains the Lab5Data directory, where the Lab5Data.zip was unzipped). Create a New Project Name: Scottsdale Description: Introduction to HEC-HMS in Scottsdale Location: X:\EngHydrology Labs\HEC-HMS Default Unit System: Metric ☑ Create Cancel Figure 3. Creating a New Project within the HEC-HMS directory using File->New. Click Create to create the Scottsdale project (see Figure 3). This will create a directory Scottsdale inside X:\....\HEC-HMS\ (the pathname for this directory will change for your application and could be located in F:\\ or C:\). Select the location to where you downloaded 3 Lab5Data.zip so that the Lab5Data and Scottsdale directories are in the same folder HEC- HMS. HEC-HMS Model Components: HMS has four main model components (you can see these by selecting Components on the top menu bar): Basin Model Manager, Meteorological Model Manager, Control Specifications Manager and Time Series Model Manager. The Basin Model, for instance, contains information relevant to the physical attributes of the model, such as basin areas, river reach connectivity, or reservoir data. The Meteorological Model holds rainfall data. The Control Specifications section contains information pertinent to the timing of the model such as when a storm occurred and what type of time interval you want to use in the model. The Time Series Model data component stores parameters or boundary conditions for basin and meteorological models. Each of the sections is explored below individually. Navigating the HEC-HMS Desktop: You can use the following four tools in the tool bar to navigate through the HMS desktop: The arrow tool lets you select any hydrologic element in the basin. You can use the zoom-in tool to zoom-in to a smaller area in the desktop, and zoom-out tool to zoom out to see a larger area. The pan tool can be used to move the display in the desktop. Hydrologic Elements: The Scottsdale basin that we will create will contains different hydrologic elements. The following gives brief information on each symbol that is used to represent individual hydrologic element. - Subbasin – Used for rainfall-runoff computation on a watershed. Reach - Used to convey (route) streamflow downstream in the basin model. Junction - Used to combine flows from upstream reaches and sub-basins. Sink - Used to represent the outlet of the physical watershed. Sink has no outflow. 3. Opening the Scottsdale Data Before we get into the details of creating the hydrological elements for the HEC-HMS model in Scottsdale, we want to orient ourselves with respect to the watershed using the provided data. To create a hydrologic model of Scottsdale, you need to create the basin file. Click: Components-> Basin Model Manager. Click: New and provide a Name (e.g., Scottsdale) and a Description. Hit Create. Figure 4 illustrates this sequence of operations to create a new basin model. Note that the name provided as Scottsdale-1 in this example (any name that you select is fine). To see the Scottsdale basin model in the Window Desktop, expand (by clicking on the + sign) the folder Basin Models and you'll see the Scottsdale basin model with a watershed icon. Now would be a good time to save the HEC-HMS project, under File->Save. 4 We are now ready to add the subbbasin boundaries, streams, streets and pipes which are stored in the Lab5Data directory. All of the files within this directory can be added using View-> Background Maps (called Map Layers in the latest version of HEC-HMS) under the main menu. This will prompt a Background Maps window, click on Add and Browse to the different shapefiles. Add the shapefiles, one by one to the Basin Model. Figure 5 illustrates an example of adding shapefiles using the Add/Browse functionality. This will now appear as a GIS-like overlay of different descriptors of the watershed (sub- basins, streams, streets and pipes). You can alter the ordering of the display of the shapefiles by using the Move up or Move down icons. Layers can also be shown or hidden for better visualization. Each map shows the entire drainage area to the outlet point and some sub- basins are included within others. It is useful to identify the topology of the basin and how the stream network defines the sub-basins within the larger watershed. Save the work using File->Save. HEC HAS 3.5 [X:Eng/lydrology Labs VIEC HMS\Scottsdale Scottsdale. hms] File Edt View Components Parameters Compute Results Tools Help LOX Scottsdale Basin Models Components Compute Results + Basin Model Manager Current basin models Scottsdale X 46388 New... Copy... Rename... Create A New Basin Model Delete Name: Scottsdale Description... Description Scottsdale Basin Model Create Cancel NOTE 10000: Finished opening project "Scottsdale" in directory "EngHydrology Labs C+MScottsdale at time 20Nov2010, 13:44:57. Figure 4. Creating a Basin Model under Components->Basin Model Manager. 5/nLab Exercise 5 Questions: This HEC-HMS exercise has been an introduction to a lumped watershed model for predicting the flood response to a design storm within Scottsdale, Arizona. Please respond to the following questions by providing both graphical representations obtained from HEC-HMS (using a print screen feature or a freeware for making screenshots) and developing short discussions. Discussions are encouraged among students during the exercise, but each student should hand in their own answers. Answers will be graded. 1. HEC-HMS Model Setup (All Students) Present a graph of the completed hydrological network (sub-basins, reaches, junctions, outlet) without the background map. The schematic should closely follow the actual location of each element. Discuss the appropriateness of the selection of sub-basins, reaches and junctions. 2. Flood Response in Sub-basins and Reaches (All Students) Present a plot (or set of plots) of the flood hydrographs that compare the response at the Basin Outlet (and its inflows) and at Junction 3 (and its inflows). Discuss how the flood hydrograph varies with location in the watershed. Present and discuss a plot of the scale-dependence of the peak discharge (Qp versus drainage area, 4) for all elements in the hydrologic model. 3. Comparison of Flood Response for 10 and 100-Yr Return Periods (Graduate students only) Develop a detailed comparison of the urban watershed response for the 10- and 100-year return period storm event at 6 hour duration. Precipitation accumulations for the 100-year event can be obtained from Figure A.58 in Appendix A of the Drainage Design Manual for Maricopa County. Assume the same temporal distribution within the 6-hour event.

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