Water Resources Assignment: HEC-RAS Flow Analysis and Hydraulic Jump Evaluation in Open Channels

Water Resources E3 Resit Coursework

Instructions:

There are two sections in this coursework. In the first section, HEC-RAS should be used to solve the open channel flow profile problem and in the second section, the provided experimental data must be used to complete the laboratory report.

Submit a combined report (single file) including Sections -I and II

Section I

Using the below given data, conduct a steady-state analysis of the open channel flow using HEC-RAS software. Prepare a report discussing the methodology you have used in completing the following tasks.

1. Briefly explain the theoretical background (model) of the HEC-RAS hydraulic solver.
2. Prepare the channel reach and complete hydraulic analysis.
3. Present the graphs showing water surface profiles and your comments.
4. Present the graphs showing various cross-sections and water surface elevations at each cross-section. Discuss various flooding scenarios
5. Show the water surface profile data in a tabular format.
6. Briefly explain your interpretation of the above results.
7. Will flooding occur (how was “flooding” defined)?
8. Is the model adequate?
9. Are there any additional changes that need to be made to the model?

Open Channel Data for HEC-RAS

• Channel reach length = 6000 m
• Bed slope of channel = 0.00028
• Manning’s roughness= 0.012 (for all sections and sides)

First station cross-section:

The reach starts with the upstream station and ends with the downstream station. The elevation of the last section should be less than that of the First section. Numbers in the parenthesis (in the figures above) represent the station number and its elevation. All length/elevation dimensions are in meters. While solving the above problem, add five more intermediate sections to the HEC-RAS model and assume that their elevations are linearly decreasing from the upstream section. Analyse the above river reach for

• a flow rate of 128 m3/s and downstream known water surface elevation of 5.8m
• a flow rate of 65 m3/s and downstream known water surface elevation of 3m.
• Any other relevant data may be assumed.

Last station cross-section (symmetrical section)

Section II

Using the below data complete the analysis of hydraulic jump data collected in laboratory. The report must be produced addressing the following issues:

1. Theoretical concepts underpinning the hydraulic jump in open channels.
2. Procedure of measurement of flow and upstream depth in the channel
3. Examine the variables of measurement.
4. Compute theoretical values of downstream depth and compare them with those measured.
5. Provide comparison graphs between the measured and computed values.
6. Discuss in detail about the error(s) in results, if any.

Sample calculations for at least one typical data point.

The flume is 30 cm wide rectangular (horizontal) channel. The flume being made from Perspex and has a smooth surface finish. Assume any other relevant data if required.