CIVL4017: Surface Water Hydrology

Project Brief

(Autumn 2022)

Assessment tasks	Weighting	Due Date & Time
Project Report 1 (approx. 500 words per student)	Tasks 1 & 2	10%	5:00 PM, Friday 08 April 2022
Project Report 2 (approx. 1000 words per student (includes improvements to 500 words per student from Progress Report 1)	Tasks 3 & 4	10%	5:00 PM, Friday 13 May 2022 (Online submission using Turnitin)
Project Report – final submission (1,500 words per student)	Tasks 5 to 8	20%	5:00 PM, Friday 10 June 2021 (Online submission using Turnitin)

Your final project report submission MUST include two-page (per member) self- reflection statement clearly identifying your contributions to the project and what you’ve learnt from the project. These pages will not count towards the word limit.

You will need to submit the report, all associated (Microsoft Excel) spreadsheets and all HEC-HMS files. Submissions is via Turnitin in vUWS. Make only one submission per team. If multiple submissions are made, only one of these submissions will be selected at random and marked. Submission will be via Turnitin in vUWS.

Make justifiable and meaningful engineering assumptions, where necessary.

Use the average of the last digits of your team members’ student ID to determine the catchment to be used for the project.

If the average is between 0 & 3 (0 ≤ 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 < 3), use catchment A If the average is between 3 & 6 (3 ≤ 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 < 6), use catchment B If the average is between 6 & 9 (6 ≤ 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 ≤ 9), use catchment C

For example,

• if the IDs of your team members are 12345678, 23456789 & 34567890, the average of the last three digits is .(8+9+0)/3=5.67. Use catchment B for your team project.
• If the IDs of your team members are 34567891, 56738491, 33567885 &

123454321, the average of the last four digits is (1+1+5+1)/4=2. Use catchment A for your team project.

Estimates of all areas of the catchment can be made using either a software of your choice or any other standard engineering method you are familiar with, including the grid approach. Anapproximateestimatesuffices– use the scale shown in the figure (each grid is 1km x 1km) for estimation.

You can estimate channel length also using approximation. Catchments A, B & C are shown in Figures on the next two pages.

1000m	CatchmentA
3 sub-catchments 1, 2, & Outlet are outlets of the three sub-catchments Centroid of the catchment is at: 150o40’ E Longitude 33o25’ S Latitude Use the scale shown in the figure to estimate areas

1000m	CatchmentB 3 sub-catchments 1, & Outlet are outlets of the three sub-catchments Centroid of the catchment is located at: 150o30’ E Longitude 33o’ 20’S Latitude Use the scale shown in the figure to estimate areas
1000m	CatchmentC
3 sub-catchments 1, & Outlet are outlets of the three sub-catchments Centroid of the catchment is at: 150o20’ E Longitude 33o32’ S Latitude Use the scale shown in the figure to estimate areas

Refer the learning guide for marking criteria.

Background

The project has been formulated to allow you to determine the differences in catchment responses before and after development. The catchment currently is undeveloped and one of the three sub-catchments is proposed for development. It is up to your team to decide which sub-catchment you want developed. You will need to identify the sub-catchment for development in your report.

Please note that the project has been formulated step-by-step (each task identified), the final report will need to be in a technical report format.

Task1.Estimationofphysicalparameters

Estimate the area of each sub-catchment. Compute the total catchment area.

Estimate the length of channels. This will be different for different catchments. For catchment A, you will need to estimate lengths of two channels (1 to 2 and 2 to outlet) whereas for catchments B & C, you only require one channel length (1 to outlet).

Task 2. Construction of rainfall hyetographs

Use the Bureau of Meteorology web site (http://www.bom.gov.au) to generate the family of IFD curves for your catchment. Use the 2016 IFD and the latitude and longitude stated in the figures (for your catchment) to generate IFD information for your site. Use1%AEP24-hrstormforfurtheranalysis. You will need to include both the IFD table and IFD curves in your report.

Use the ARR Data Hub web site (https://data.arr-software.org/) to generate total rainfall hyetograph for the storm generated in the above step. You will need to include the total rainfall hyetograph, both table and histogram, in your report.

Extract the initial and constant loss values from the ARR Data Hub web site. Make necessary adjustments and construct the rainfall excess hyetograph. You will need to explain how you achieved your result and include this in your report. Graphical representation suffices here.

For post-development condition, assume that both the initial loss and continuing loss will be reduced by 50% for the sub-catchment you’re proposing to develop. Remember you’re developing only one of the three sub-catchments, therefore loss values and rainfall excess will change only for one sub-catchment.

Task 3. Construction of unit hydrographs of desired duration

You will be generating 15-minute unit hydrographs for your sub-catchments using the 15-minute unit hydrograph for a 6.15km² catchment given in the table below and making reasonable assumptions (explained below).

You may then be required to convert thus generated 15-min unit hydrograph to another duration unit hydrograph to meet the time interval of the rainfall excess hyetograph. You may need to follow S-hydrograph method to achieve this outcome.

Use of spreadsheet will save considerable time, as the process involves repetitive computations. You will need to include your spreadsheet.

A 15-minute unit hydrograph for a catchment of 6.15km² is given in the table below.

Time(min)Discharge(m³/s) 0 5 10 15 20 25 30

0 0.50 1.80 3.50 4.0 3.75 2.26

Time(min)Discharge(m³/s) 35 40 45 50 55 60 65

1.60 1.04 0.70 0.50 0.30 0.18 0.12

Time(min)Discharge(m³/s) 70 75 80 85 90 95 100

0.09 0.06 0.04 0.03 0.02 0.01 0

Use the above 15-minute unit hydrograph to compute ordinates of the 15-min unit hydrographs for your sub-catchments using the catchment area as the scaling factor. For example, if the area of your sub-catchment is 3.075km², each ordinate given in the above table will be half of what’s listed. The resulting 15-minute unit hydrograph will look like,

Time(min)Discharge(m³/s) 0 5 10 15 20 25 30

0 0.25 0.90 1.75 2.00 1.875 1.13

Time(min)Discharge(m³/s) 35 40 45 50 55 60 65

0.8 0.52 0.35 0.25 0.15 0.09 0.06

Time(min)Discharge(m³/s) 70 75 80 85 90 95 100

0.045 0.03 0.02 0.015 0.01 0.005 0

Similarly, if the area of your sub-catchment is 12.3km², each ordinate will be double of what’s listed in the table. The resulting 15-minute unit hydrograph will look like,

Time(min)Discharge(m³/s) 0 5 10 15 20 25 30

0 1.00 3.60 7.00 8.00 7.50 4.52

Time(min)Discharge(m³/s) 35 40 45 50 55 60 65

3.20 2.08 1.40 1.00 0.60 0.36 0.24

Time(min)Discharge(m³/s) 70 75 80 85 90 95 100

0.18 0.12 0.08 0.06 0.04 0.02 0

Note that you may need to generate up to 3 unit hydrographs (this will depend on the areas of each sub-catchments).

Construct Δt-hr unit hydrograph (where Δt-hr is the time step of rainfall excess hyetograph) from the 15-minute unit hydrographs generated for your sub-catchments. You will need to use the S-hydrograph method to achieve this. You will need to explain the process you followed in your report. Make sure to verify your results by checking volumes after each computation.

Task 4. Construction of storm hydrographs

Construct the storm hydrograph for each sub-catchment using rainfall excess (task 2) and respective Δt-hr unit hydrographs generated above (task 3). The 3 storm hydrographs you’ve generated are the responses at the outlet of respective sub-catchments for the catchment in natural condition. Let us call it predevelopment storm hydrographs.

Task 5. Construction of network diagram, routing through channels and hydrograph computation at the catchment outlet

Your team will need to construct the hydrologic network to show connectivity of sub-catchments, channels and reservoirs (if any).

Your team will require to extract channel properties for routing the hydrographs through channels using Muskingum routing method. For this, assume the following.

weighting factor, x= 0.2

Use average channel velocity of 1.2m/secto estimate average flow velocity in the channel. Use this average flow velocity to estimate travel time constant, K.

Use these values of x & K to route relevant hydrographs through respective channel(s) and compute the hydrograph at the outlet of the catchment.

Your team will need to discuss how you obtained these, include sample calculations and show the final result (both table and figure). All computations will be performed using a spreadsheet and the spreadsheet will also need to be submitted.

This completes generation of pre-development hydrograph at the catchment outlet.

Task 6. Post-development hydrographs

Your team will need to repeat the process, taking into account development of one of the sub-catchments. For the catchment being developed, use the following.

Both initial loss and continuing loss will be reduced by 50%.

15. minute unit-hydrograph will have the following characteristics.
    • Peak discharge will increase by 25%
    • Time to peak will decrease by 10%
    • Time base will decrease by 20%

Use the above adjustments to scale and generate meaningful post-development 15-min unit hydrograph. Your team will have to ensure that the volume balance works out. This may require a few iterations.

Your team will then need to construct Δt-hr unit hydrograph (post-development) for the sub-catchment being developed and use this to generate postdevelopment catchment response.

Task 7. Comparison of Pre- and Post-development hydrographs

You will need to compare the pre-development and post-development hydrographs. Present your results in graphical form and present salient values in a tabular form. Analyse and discuss your results.

You will then need to propose a solution that will ensure that the peak of the postdevelopment hydrograph at the outlet does not exceed the peak of the predevelopment hydrograph at the outlet. You may have to design a reservoir incorporating outlet structures to achieve this. If you’re to use this approach, you will need to route the post-development hydrograph through the reservoir.

You will need to discuss your strategy, provide the size of the reservoir and the details of outlet structures in your report.

Task 8. Use HEC-HMS to verify your results

This is the last step. You will use HEC-HMS (latest version) to verify your results. You will need to include all HEC-HMS files in your submission.