CE 3354 Engineering Hydrology
HEC-HMS Analysis Project

Team Members
1. LAST NAME, FIRST NAME, R00000000
2. LAST NAME, FIRST NAME, R00000000
3. LAST NAME, FIRST NAME, R00000000
4. LAST NAME, FIRST NAME, R00000000
5. LAST NAME, FIRST NAME, R00000000

Problem Statement

Figure 1 is a map of a portion of Concho County, Texas. In the Southeast corner of the map is Eden, Texas. A US highway runs nearly East-West through Eden and another US highway runs North-South.

Figure 1. Harden Branch Creek near Eden, Texas

The analysis task is to determine the water elevation at the crossing conveyed through the existing 3-barrel 6X6 box-culvert system at an appropriate design risk level, and assess how much the water surface elevation might be reduced (lowered) by adding an additional barrel (4-barrel 6X6 box culvert system).

Document the study in an engineering report, with appendices as necessary that contain the underlying data used in the model(s). The analysis anticipates that HEC-HMS will be used for hydrology up to the culvert system (or bridge) on US 87, and to the next structure on US83

Technical Requirements

The engineering project report should consist of the following (minimal) contents.

1. Letter of Transmittal
2. Executive Summary
3. Study Purpose
4. Existing and Proposed Conditions
5. Hydrologic Analyses including:
6. Discharge and Water Surface Elevation Estimates
7. Conclusions and Recommendations
8. References
9. Appendix (sample calculations, data, etc.)

Additional Guidance

The two reservoirs are SCS reservoirs designed to capture and release water over 7 days. That is, once full but not over the spillway, the reservoir should drain in about a week. Use that information to approximate an appropriate release mechanism in the simulation model(s). (Probably an orifice and weir arrangement, but read the user manual for other possibilities)

You will have to construct some kind of storage curves for the reservoirs and may have to use algebra and curve fitting to complete such curves. Pursuant to those curves, there will be some kind of stage-discharge relationship.

You may assume that the spillways crest about 4 feet below the dam crests and the spillways are about 50 feet wide.

The road crossing itself is also treated as a reservoir (with outlet structure). Flow over the top of the road is a spillway – read in HMS manual how to conceptualize.

You need to make your own exhibits (drawings, and map overlays). A basemap image is available below that you can use, but you need to make your own delineations and measurements.

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Suggested Workflow

1. Identify team member duties in the context of tasks listed below.

Initial Report Components

1. Examine the example report templates;
2. Build an empty report, use the templates below for section headings;
3. Start the watershed description section;
4. Create the crossing configuration section;
5. Create the design risk level sub-section; and construct the indicated design storms (construct your storms using NOAA Atlas 14, not the DDF Atlas).
6. Layout subbasins for modeling; make measurements (areas, stream lengths)

Have the report skeleton completed before workshop II so you can refine the report during that class meeting

Report Refinement Components

After you have an initial report skeleton

1. Complete the watershed description and complete (repair) the design storm graphics, as well as supply narrative for these sections.
2. Estimate the CN for the three (or more) catchments, as well as make needed measurements (distances) and areas.
3. Estimate basin lag time (time of concentration) for the three sub-catchments using appropriate methods.
4. The elevation-area tables needed for the three reservoirs are conceptually identical to the elevation-area question on Exam 1, except you need to do the estimates for several different elevations, including the spillway elevation and the dam crest elevations.
5. Use Google Earth to estimate the size of the riser pipes on the two dams.
6. Use the topographic map to make cross sections along the three routing elements depicted in the HMS conceptualization.
7. You should have HEC-HMS running by this part of the project study
8. You should evaluate both crossing configurations

Have the refinement report available for workshop III and beyond so you can update as your team builds more content.

Report Finalization Components

1. Make your HMS production runs for the existing and proposed geometry for the four different design storms.
2. Record the peak pool elevations at the US-87 crossing for each case and each storm (8 simulation in all).
3. Interpret the elevations and establish whether the road is inundated or not.
4. Decide if adding the two barrels reduces inundation for the different storms.
5. Write the Executive Sumary and Conclusions and Recomendations sections.
6. Copy edit the final report look for:
   1. Spelling
   2. Grammar (Tense, Active/Passive voice)
   3. Caption All figures
   4. Caption All tables
   5. Figure call-out in the text
   6. Table call-out in the text
   7. Update all the cross references, so the table of contents, table of figures, and table of tables, shows correct pages for indicated items;
7. Write the Transmittal letter, signed by each team member that contributed to the project

Have the report ready for workshop V so you can copy-edit the report during that class meeting and prepare the powerpoint for class presentation

Presentation

1. Using the report as a guideline prepare a powerpoint presentation.
2. The presentation is to be 5-10 minutes long, all team members must present a portion and must include
   1. Executive Summary
   2. Study Purpose
   3. Existing and Proposed Conditions
   4. Hydrologic Analyses including:
   5. Discharge and Water Surface Elevation Estimates
   6. Conclusions and Recommendations

References

1. Initial Report Example (pdf)
2. Refinement Example (pdf)
3. Refinement Example (pdf)
4. Study Area Map (jpg)
5. Project Watershed Base Map (jpg)