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Volumes Calculation Method Comparison in Cross Sections and Volumes
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on 23 August 2016 11:21 AM

Calculation Method Comparison for Cross Sections and Volumes

It seems that everyone has a slightly different idea about how volumes should be calculated. The original method (Standard HYPACK®) was an attempt to make everyone happy. The table below gives a brief comparison of the computation methods included in the CROSS SECTION AND VOLUMES program. Select your computation method in the Survey Tab.

Name

Method       

Contour Dredging

Pre-dredge vs.

Post-dredge

Center Line

Reference

Grades  

Target Number of Segments

Fill Vals.

Standard HYPACK®

Prismatic

Yes

No

No

2

Up to 20

Yes

End Area 1

End Area

Yes

No

No

3

3/Non-Std

No

End Area 2

End Area

No

No

No

3

3/Non-Std

No

End Area 3

End Area

Yes

Yes

No

3

3/Non-Std

No

End Area No Segments

End Area

No

No

No

2

N/A

No

Philadelphia

End Area

Yes

Yes

Yes

2

4/Non-Std

No

Norfolk

End Area

No

No

No

4

3/Non-Std

No

Savannah

End Area

No

No

Yes

2

3/Non-Std

No

Jacksonville

End Area

Yes

Yes

No

3

3/Non-Std

No

Panama City

End Area

No

No

No

3

4

No

Chinese 1 End Area 1

End Area

No

No

No

2

3, 5 or 7

No

Chinese 1 End Area 3

End Area

No

Yes

No

2

3, 5 or 7

No

Chinese 2 End Area 1

End Area

No

No

No

2

3

No

Chinese 2 End Area 3

End Area

No

Yes

No

2

3

No

GLDD 1

End Area

No

No

No

3

3/Non-Std

No

GLDD 3

End Area

No

Yes

No

3

3

No

Kingfisher

End Area

No

No

No

3

3

No

Beach Predredge

End Area

No

No

No

3

Up to 20

No

Beach Postdredge

End Area

No

Yes

No

3

Up to 20

No

Zone Listing Predredge

End Area

No

No

No

2

N/A

No

Zone Listing Postdredge

End Area

No

Yes

No

2

N/A

No

End Area No Template

End Area

No

No

N/A

N/A

No Template

No

The Average End Area Method calculates the average of material above or below a grade. It is a standard used throughout the hydrographic and dredging industries. Although it is not the most accurate method, it is simple enough that results can be verified by hand calculation.

The following figure gives the basic idea behind End Area calculation. The topmost area in the graph is the area above the design template, and the middle layer is the area above the subgrade template. If a supergrade is included in your design, it will be the third level.

Channel Cross Section with End Areas Shaded In

The legend, in the lower portion of the window, may give volumes figures for each of the defined areas of the cross section according to the method you have chosen.

The CROSS SECTION AND VOLUMES program approximates area by interpolating soundings every foot (or meter) along the survey line, then summing distances to the template across the entire line.