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CE 394K.2 - Surface Water Hydrology

College of Engineering
The University of Texas

                                                                                                                                                                                         

Exercise 1




QUESTION 1

The following picture shows a schematic of Waller Creek using HEC-HMS.

 

QUESTION 2

The following table shows the area of each subbasin on Waller Creek. Also presented is the total drainage area for the entire watershed.

Subbasin No.

Area (km2)

12

3.602

13

6.912

14

0.966

15

0.563

16

1.633

17

0.437

18

0.252

Total Area (km2)

14.365

 

QUESTION 3

The parameter values for subbasin 13 include:

  • Loss rate – this parameter measures the abstractions due to infiltration
  • Initial loss is set a 5mm – this parameter measures the initial abstraction which occurs as the storm begins
  • Constant rate refers to the rate at which water is lost due to abstraction throughout the duration of the storm.
  • Imperviousness refers to the amount of ground cover that cannot be infiltrated by runoff.

The parameter values for reach 10 include:

  • The river routing method used is the Muskingum method which is a flow routing method for channels with a variable discharge-storage relationship. The procedure is used to determine the time and magnitude of flow.
  • Muskingum K refers to the travel time of the flood wave.
  • Muskingum X refers to the storage in the reach.

 

QUESTION 4

The following picture shows the design precipitation input file from HMS.

 

QUESTION 5

For a 3 day simulation with 10 minute intervals there will be a total of 432 intervals.

 

QUESTION 6

The following table shows the peak discharge, the drainage, and the peak discharge/drainage area for each of the six outlet points on Waller Creek.

Outlet Point

Peak Discharge (cms)

Drainage Area (km2)

Q/A (cms/km2)

Junction w/ Hemphill

40.443

10.514

3.846585505

MLK

40.107

11.48

3.493641115

15th St.

39.892

12.043

3.312463672

7th St.

39.781

13.676

2.908818368

1st St.

39.405

14.113

2.792106568

Colorado River

39.119

14.365

2.72321615

 

QUESTION 7

In order to determine the design discharge of Waller Creek at 15th Street, a 100-year design storm was used for the precipitation file in HMS, shown below.

Also, I changed the percent impervious coverage as the creek moves through Austin, shown below.

 

 

The design discharge using these input values was determined to be 65.029 cms. A hydrograph of the discharge is shown below.

These values can be double-checked by referring to the stream gauge data provided by the USGS or use a plot of flow vs. drainage area which has previously been determined.