EXAMPLE APPLICATION

Technical Note DOER-N4

May 1999

EXAMPLE APPLICATION: A sample application of the grain-size depth of residence screening

model is given below. In this example, the driving force for sediment motion is a current of

0.2 m/sec (0.66 fps) combined with a wave that is 3 m (10 ft) high with a 10-sec period. The

sediment is identified by a median grain size (D50) of 0.2 mm (0.0079 in.). The program input and

output is provided below where program text (requests for information) is given in italics and

user-provided answers are given in bold.

Program to determine depth of residence

Input wave height , wave period, current

velocity and median grain size. Program

determines depth at which sediments will

remain stationary at these conditions.

Note: Input values must be greater than 0

Do you want to input in

metric (1) or English (2) units?

Input wave height (m)

Input wave period (s)

>10

Input current velocity (m/s)

>0.2

Input D50 grain size (m)

>0.0002

FOR THE FOLLOWING CONDITIONS:

wave height =

3.00000

(m)

wave period = 10.0000

(s)

current velocity = 0.200000

(m/s)

grain size =

0.200000E-03 (m)

SEDIMENT WILL NOT MOVE AT A

DEPTH OF 26.5176 m or greater

As the example shows, the program determined that for the given hydrodynamic conditions, the

given sediment will be stable at water depths greater than 26.5 m (87 ft). Hence, if this screening

tool was being used to determine the depth at which sediments for a dredged-material capping

project would be stable, then as an initial estimate one could say that depths would have to be greater than

26.5 m (87 ft). Conversely, if the desire was to have the sediment move under the given conditions,

then as an initial estimate one could say that the depth would have to be less than 26.5 m (87 ft). The

results should be considered a rough estimate. If the actual depth at which the sediment was to be

placed was nearly 26.5 m (87 ft), then a more thorough evaluation of the site would be required. If

the actual placement site was much deeper or much more shallow than 26.5 m (87 ft), one could