Assignments
Below some assignments for this case study are listed by the objective to which they are most related. You will be given instructions in class about any changes to the problems and due dates. For example, your instructor may combine assignments to reduce the number of reports that you will need to write. Reports are not required of all assignments, and this is totally at the discretion of your instructor. The report format, which is preferred for the case study is included in Assignment 1. An example report is included in the documents under 'Resources'. You will be given the solutions to each assignment after they have been collected. If some of the links under each assignment have been broken you can check the Student Data Package you were given.
Hydrology
Wetland Design
Hydraulic Design
Assignment 1 - Data Collection
This assignment exists to introduce you to data collection for GIS-related problems. You may have been given data in past assignments for your classes that use this software, but the reality is that the software is only as good as the quality of the data. Therefore, it is important for you to understand how to obtain good quality data. Using the source(s) of your choice you must obtain the following for 'Ag' Heritage Park: DEM of at least 10 meter x 10 meter resolution, orthoimagery (aerial image) of at least 1 meter x 1 meter resolution, LULC map (2006 or newer), soils data shapefile, and a topographic map (2011 or newer). You can also obtain contour data to compare with the next assignment if you choose to do so. Unfortunately, Alabama does not currently have a data clearinghouse, but this may change in the future. Once you have obtained all the data, project and import the data into ArcGIS in the Alabama State Plane East Coordinate System. Screen capture as needed to show your instructor that you have completed the assignment (include at least one screen capture of the coordinate system, projection, and datum).
Hint: There are nationally recognized sources that have the data listed above, but it is always good still to check local sources (data clearinghouses, libraries, or state and municipal authorities) for the highest quality data.
Link: General Procedure for Projecting Data in GIS
Deliverables: Four screen captures of GIS data, at least one screen capture of metadata, and one screen capture of the topograph as it will be in PDF format. Put all of these in one neatly organized report; it does not need to be long, just include enough to document your understanding of the process.
Report Format: Reports should be only a few pages long with no more than one to two pages of writing unless otherwise noted. A general guideline is to include the following in your reports: title page, introduction, methods, results, and conclusion. Quality rather than quantity is the key here.
Assignment 2 - Data Preparation and Management
You will learn to generate your own contours in this assignment. Using the DEM that you acquired in the first assignment, generate contour data with the following contour intervals: 10-foot, 2-foot, and 1-meter. Overlay each of these data on the aerial image that you acquired in the previous assignment. As always, make sure that you are using the correct coordinate system and projection. After you have done this, create a template title block, which you will use for future assignments. The template title block should be formatted as a portrait with dimensions of 8.5" x 11" that contains all of the following information in a neatly organized format:
{Title}
Created by: {Name}
Date: {##/##/##}
Datum: {Datum}
Projection: {Projection}
Coordinate System: {Coordinate System}
{North Arrow}
{Scale Bar}
{Legend}
{Logo} (Optional)
Use your own judgment as to whether an item should be included within the title block itself or as a stand-alone element on the map. Creativity will not be discouraged, but your presentation should not be distracting. Here is a link to an example map of data for Auburn, Alabama in portrait format, and here is a map of erosivity in Lee County in landscape format. Please do not merely copy either of these formats.
Hint: Pay careful attention to the correction factor that you use for customary versus SI units. Also, the 'Size and Position' tab under a neatline's 'Properties' is very helpful when designing your own template. You will use the contour data in ACAD much later, but you may want to go ahead and do it now while it is in front of you. formats.
Optional: Export the 2-foot contours to ACAD using the link provided below as a guide.
Link: Exporting Contour Data to ACAD
Deliverables: Three maps with (one for each contour interval) and a fourth with all three intervals in report format similar to the previous assignment. From this point forward, you should use this template for any formal deliverable in map format (screen captures are not formal and will be specified when you can use them). Your presentation of the deliverables will also be considered in your grade hereafter.
Assignment 3 - Watershed Delineation
First, using either the contours that you generated or those that you have downloaded from a data clearinghouse, delineate the watershed by hand. You may also use the solution for Assignment 2 if you prefer to do that. Use the culvert outlet of 'Ag' Heritage Park as the point to begin delineation and the 2-foot contours unless you are instructed otherwise.
Second, delineate the same watershed using ArcGIS. The point of this exercise is not to add unnecessary work to you but to help you identify weaknesses in your own understanding of watershed delineation. Pay particular attention to where your delineation by hand may deviate from the computer generated watershed (this is a simple way to check both the computer and hand delineation with each other).
Hint: The placement of your outlet point and the contour interval can affect your watershed boundary. Also note that this is the natural watershed, and that urban watersheds can be different from their natural counterparts, which will be covered in the following assignment.
Deliverables: One map of the watershed delineation formatted with the template from the previous assignment in report format, and your delineation by hand.
Assignment 4 - Watershed Boundary Correction
Using the delineated watershed from ArcGIS and AU Campus Base Mapping, manually correct the watershed to reflect the storm water infrastructure. You will need to edit the data layer to include areas that are routed into the watershed and to exclude areas that are routed out of the watershed. You will either be given or be asked to digitize the storm water infrastructure in the watershed. You may need this data for determining the time of concentration later. Label all the channel lengths that you digitize with four significant digits, and be as accurate as possible to match your digitized data with that of the campus base mapping.
Hint: Convert the watershed delineation to a polygon feature class. Make sure you understand the option 'Simplify Polygon'. If you are not given the SW data, then you will need to create your own field called 'Length' and populate it accordingly.
Deliverables: One map of the corrected watershed delineation and storm water infrastructure labeled as required above. Document each edit by showing a screen capture and give an explanation for the correction you make to the boundary. Do not be excessive here, you can probably effectively communicate all of your edits with no more than 5 and no less than 3 screen captures. Use the same formatting as previous assignments.
Assignment 5 - Basin Model Creation and Subbasin Delineation
Open HEC-HMS version 3.5 or newer and create a new project for AHP. Sketch the basin model on paper using hydrologic features including: subbasins, reservoirs, reaches, diversions, etc. After you are confident that you have a good representation of the watershed, open ArcMap and delineate each subbasin that you have identified and overlay them on the original watershed delineation. Make sure the subbasin boundaries are aligned with the original watershed boundary. If you plan on creating a background map (Assignment 6), you should complete tasks in the following order:
1) sketch your basin model (on paper)
2) complete the subbasin delineation (in GIS)
3) export to ACAD
4) generate the map file
5) import the map to HEC-HMS
6) complete the basin model (in HEC-HMS).
If you are not going to generate your own map you can skip the steps that pertain to the background map and either use the solution from Assignment 6 or no background map at all.
Hint: There is more than one subbasin for this watershed, and you will need to pay careful attention to the AHP pond as it will determine how your subbasins are divided. Each subbasin has a distinct outlet location.
Deliverables: One screen capture of the basin model (showing how features are networked to the outlet) and a map of the subbasin delineation with each subbasin appropriately labeled. Explain the reasoning behind why you represented your watershed with the specific features you have selected and why you have selected each method for different features.
Assignment 6 - HEC-HMS Background Map Creation
For this assignment you will create your own background map to be used in HEC-HMS. A tutorial video link will walk you through this process. In order to complete this assignment you will need to download an application to run a macro in ACAD. If you can not get this to work, your instructor can give you the solution file to this which includes the map file you need for the background map. Pick the current version of ACAD and the bit type that is appropriate for your processor (typically 64-bit). If the link is broken, go to 'Load Application' in ACAD and you will eventually be redirected to the most recent link to the download.
Hint: This step should always come after you have delineated subbasins. Some of the steps in the tutorial are outdated and/or do not apply to current versions of ACAD.
Link: HEC-HMS Background Map Creation
Download: ACAD VBA Module
Deliverables: No deliverables. The map exists to help you visualize the watershed you are modeling.
Assignment 7 - Basin Model Feature Characterization
Now you need to characterize each feature you have identified in your basin model. You should fill in all of the parameters related to each feature excluding reservoirs if you have any. In reality, you would need to either digitize your own LULC data or use data that has already been generated, but for this assignment your instructor may provide you the LULC and soils data for this assignment. Use what skills you have learned in GIS to accurately characterize each feature. Choose the loss, transform, and routing method carefully for each feature. Do not worry about 'Surface', 'Canopy', 'Baseflow', or 'Loss/Gain' methods at this time. Your instructor may provide you some extra resources for this assignment because it can become difficult if you are not confident in what you are doing.
Hint: If you are digitizing your own LULC data, the 'Overlay' tools will become very handy. 'Intersect' is particularly useful for when you are trying to determine the area of each land cover type for each subbasin. Remember that the time of concentration is the longest hydrologic pathway and may not necessarily be connected to the watershed boundary.
Deliverables: A map for both LULC and soils data, a screen capture showing the path for time of concentration in each subbasin and for the entire watershed, and a screen capture of the 'Subbasin Area', 'Loss', 'Transform', and 'Routing' summary pages. organized spreadsheet tables should be included as well.
Assignment 8 - Populating Model Components in HEC-HMS
Now your basin model is fairly complete, and it is time to finish other components of the model, which include the meteorological model, control specifications, and paired data. First, you will need to create storm events for your model as required by the City of Auburn SWMM. Therefore, at a minimum you should have the 2, 5, 10, and 25-year, 24-hour storm events. Create a control specifications component that is called 'AHP Event' that starts on January 1, 2014 at 00:00 and ends on January 2, 2014 at 12:00 with a 15-minute interval. Now you will need to create a storage-discharge function under 'paired data'. Now populate the function you created by using a spreadsheet program to calculate the storage and discharge at regular stage intervals. For this you will need some specific information about the AHP Pond and existing hydraulic structures including a) the area of the pond surface at regular stage intervals (2 ft or better) and b) the size, location (with respect to stage), and type of hydraulic structures. Build a stage-discharge relationship to each hydraulic structure and a stage-storage relationship to the AHP Pond; then build the storage-discharge table according to stage. Your instructor will have the files you need to build all of these tables. Once you have finished the storage-discharge table, remember to link the reservoir in the basin model to the table by changing the storage method to 'Storage-Discharge' and selecting the table you just created. For the initial condition select 'Storage' and input 13 AC-FT.
Hint: Use the 'User's Manual' and 'Technical Documentation' to work through any problems that may arise. There are links provided in Resources as well as in the 'Help' function within the HEC-HMS software. When you are building the storage discharge table and the table for each of the hydraulic structures, pay close attention to the drop inlet. Treat the inlet as a broad-crested weir for the 36" riser and then overlay the flow for the 30" orifice pipe and take the lowest flow for each stage above the riser. The 36" riser allows water in very quickly, but is soon limited by the 30" orifice, thus lowering the effective flow rate at stages that are much higher than the riser.
Deliverables: A spreadsheet table for each of the existing hydraulic structures including both the drop inlet and the emergency spillway (ignore the 6" gate valve at the moment), a storage-discharge table, and a screen shot of all the components of your model expanded excluding the basin model (meteorological model, control specifications, and paired data). Make sure to document in your report why you have selected specific methods and to present your tables neatly with appropriate headers and formatting.
Assignment 9 - Hydrograph Generation in HEC-HMS
Now everything is ready to run the model on an event basis. Later assignments will revisit the model and expand it to run continuous models with the completed wetland design. You must now create simulation runs for each of the storm events required by the City of Auburn SWMM. Select the appropriate meteorological model for each run. Once you have the simulation runs created, select 'Check Parameters' under 'Compute' and the program will let you know if there is an issue with any of your components. If there are not any issues, select 'Multiple Compute' under 'Compute' and run all of your simulations. Close all of the windows (completed or failed) and look at the 'Results' tab for each storm event. Look at the storage in the AHP Pond and the hydrograph at the AHP Outlet for all required storm events. When preparing your deliverables, you can edit the way the graph looks by exploring 'Graph Properties' under 'Results'. It is not necessary to edit your graphs for this assignment. There are only two deliverables for this assignment including a report of about 1,000-2,000 words of quality writing interpreting the two graphs (or any graphs you include to aid the discussion).
Hint: When you want to overlay multiple graphs, expand the features you want to see before selecting them so that you can get a single element at a time rather than several elements (hold ctrl + select elements). You may not be able to select more than five graphs to display at a time (newer versions of HEC-HMS may allow for this). For example, if you want to see only the total outflow, expand the feature of interest (for all storm events) and select only the elements called 'Outflow' for the given feature under each simulation run of interest.
Deliverables: One graph of the storage in the pond and one hydrograph showing the outflow at the AHP Outlet for the required storm events. Make sure to explain in your report what is happening at each point in the storage graph and the outlet hydrograph. Think about where each hydraulic structure becomes visible in the graph and remember that you are not at the outlet of the pond but at the outlet of the park, so there will be some slight distortion. If you need to you can view what is happening at the outlet of the pond to make further comments.
Assignment 10 - Storm Water Wetland Design Parameters
Using a method of your choice, determine the volumetric parameters of a storm water wetland that will retain and treat the 'first flush' of runoff from its watershed. At a minimum you must have all of the following parameters defined: runoff volume, temporary pooling depth, and surface area. You should also determine what the permanent pooling depth of each zone of the wetland should be (e.g. forebay, pools, outlet, etc.) and the surface area of each of those zones. You may also want to try to determine the approximate shape of the wetland by sketching or spreadsheet modeling because you will be using that to design the wetland later. It is not necessary at this time to calculate drawdown time or detention time as that is covered in the hydraulic design assignments.
Hint: You have a site with slopes that are relatively unfavorable to a wetland ecosystem. The shape of the property boundary is also difficult for this site and may or may not interfere with the required surface area. Make sure that your design is resilient to the runoff volume and rate of discharge while staying within the realistic constraints of slope steepness (no steeper than 3 to 1 slope) and the property boundary of AHP. Designing for resilience may require you to check the velocity of flow through the wetland (at multiple points) to insure that there is no significant aggradation or degradation occurring.
Deliverables: Write a report in the same format as previous assignments (not too much) that explains your design and the methods you used to arrive at that conclusion. Make sure to include tables and figures of the model with notes that include relevant equations and assumptions that you make.
Assignment 11 - Evapotranspiration
Use the Blaney-Criddle method for determining average monthly evapotranspiration (ET) for Auburn, Alabama. Create a bar graph of the entire year showing average ET and rainfall for each month in (mm / month). Assume a crop coefficient of 0.85 for calculating the actual ET. Cite the sources you use to complete the assignment. You should create a spreadsheet that contains each month's a) potential ET, b) actual ET, and c) rainfall from which you will create the bar graph.
Hint: You can find rainfall data from different government agencies or almost any weather service online. Make sure you are getting long term averages and not just one year's rainfall data.
Deliverables: Your instructor will give you details about the submission for this part of the assignment. However, it should include your model of the average monthly ET and the graph that you had to generate. Include notes on the spreadsheet of how you calculate each portion of the assignment.
Assignment 12 - Site Design for AHP: Storm Water Wetland Design
Following guidelines in class and from the ACES LID Handbook, you are to draft a site plan for the wetland design parameters in Assignment 10. At a minimum, you should draw your wetland design layout and side profiles (as many as are necessary) and include a grading plan for the site design. Do not worry about hydraulic structure design for this assignment. Make sure that you are abiding by local regulations, and to include relevant permitting doucumentation.
Hint: You can create a wetland with more than one permanent pooling depth in order to accommodate difficult slopes that may be found in the potential wetland area.
Deliverables: As many drawings that are necessary to communicate your design plan in addition to a report that is formatted similarly to the previous assignments. There should be at least one drawing for each of the following: existing site, proposed site design, grading plan, and side profiles of the wetland design. 11" x 17" is the recommended page size, but you may increase size if you so desire. For all printing you will be responsible for managing the time it takes and to cover printing charges if there are any.
Assignment 13 - Continuous Modeling (Advanced and Optional)
Model the continuous operation of the wetland system you design complete with hydraulic structure design (from later assignments). Look at multiple years of simulated rainfall (some historical data is provided for wet years, average years, and dry years) and evaluate the performance of the design in both normal and extreme conditions. What changes to your design would make it more appropriate for normal conditions? What changes to your design would make it more resilient to extreme conditions?
Hint: Think about the intended purpose of the wetland system and about how to cut back on unnecessary design components (for cost savings, simpler construction, etc.) and how might a simpler design be a better choice.
Deliverables: Submit a report in the appropriate format showing figures and discussion how the design can be altered to achieve a better performance.
Assignment 14 - Low Flow Hydraulic Structure Design
According to the 'City of Auburn SWMM' (page 4-4), there are three different types of outlet structures used for storm water storage systems including drop inlets (with pipes), weirs, and orifices. The 'ACES LID Handbook' (page 54) suggests that storm water wetlands should have orifice hydraulic structures in order to meet specific drawdown times and weirs to route overflow from large storm events. If you would like more information about wetland storage systems read also pages 47-51. Assume no friction losses for this assignment.
1) Design orifice hydraulic structure(s) for a wetland storage system with a surface area of 1.5 acres, a temporary pooling depth of 1 foot. Additionally, there is a base flow into the wetland system of 0.2 cfs. Determine the appropriate diameter (in.) of the orifice(s) for drawdown times of 2, 3, 4, and 5 days in spreadsheet format.
2) Specify the material, maker, schedule, etc. of your orifice and include a schematic/drawing (with dimensions) of the orifice design in your submission.
3) If you had an orifice with a diameter of 1.0 inches, how full would the pipe be (%) after a long period of time? Assume no rainfall in that period of time.
Hint: This assignment is more open-ended than you are probably accustomed to. You are responsible for each design decision and should therefore document your reasoning for each decision you make. You will use this design spreadsheet in a future class to create a hydraulic site plan.
Deliverables: A spreadsheet with notes in the spreadsheet for formulas/equations used and assumptions made for each of the inputs in each equation. Follow the same format used in class assignments.
Assignment 15 - High Flow Hydraulic Structure Design
Following the design convention in the 'ACES LID Handbook' you will now design a high flow capacity hydraulic structure. Usually this structure is a high capacity weir with equations given on page 54. Again assume no losses due to friction.
1) Design a high capacity broad crested weir for the same wetland system described in Assignment 15. The permanent pool elevation is at elevation 310' and receives a peak flow rate of 200 cfs. Determine the length of the broad crested weir for driving head depths of 0.5, 1.0, 1.5, 2.0 and 2.5 feet in spreadsheet format.
2) Specify the material, maker, schedule, etc. of your weir and include a schematic/drawing (with dimensions and elevations) of the weir design in your submission.
3) What is the elevation of the orifice so that the permanent pooling depth remains at 310' and the temporary pooling depth is 1 foot? What adjustment to your previous assignment would you need to make to reflect this? Show this in your schematic from part 2.
Hint: For part 3, think about what 'H' is defined as in the orifice equation. You may have to do a little reading to discover what is commonly done for weir construction.
Deliverables: A spreadsheet with notes in the spreadsheet for formulas/equations used and assumptions made for each of the inputs in each equation. Follow the same format used in class assignments.
Assignment 16 - Site Design for AHP: Hydraulic Design
Create a hydraulic profile for the AHP wetland design you completed in Assignment 12. Be sure to include, temporary and permanent pooling depths and elevations of all hydraulic structures (proposed and existing). You are then to evaluate two groups of scenarios:
1) Water levels for the 2, 5, 10, and 25-year storm events
2) Water levels for summer drought conditions (no base flow) after a period of 10, 20, 40, and 60 days
Hint: If the wetland design you completed previously has multiple pooling depths, you will be responsible for each of those depths in the hydraulic design.
Deliverables: As many drawings that are necessary to communicate your design plan in addition to a report that is formatted similarly to the previous assignments. There should be at least one drawing for each of the following: existing site, proposed site design, and profiles of the wetland hydraulic design. 11" x 17" is the recommended page size, but you may increase size if you so desire. For all printing you will be responsible for managing the time it takes and to cover printing charges if there are any.