For the remaining part of this problem, either the value of F^n equal
to 220 nautical miles as determined from Figure 3-15 for
= 91.6,
= 59.4 can be used with the deepwater forecasting curves, or else
Equation 3-40 can be used, as modified,
H = 0.0555 UR Jf' + AF
O
K.
y e
along with Equation 3-36
To = 2-13
•
Fg is defined below.
The latter being a numerical method is easier to use and more accurate
than the graphical method of using forecasting curves.
The procedure for computing wind waves over the Continental Shelf
will be illustrated by using the bottom profile off the mouth of the
Chesapeake Bay and the standard project hurricane developed for the
Norfolk area. The storm surge computed for the standard project hurricane
and 2.5 feet of astronomical tide are added to the mean low water depths
to obtain the total water depth for wave génération. Refraction is
neglected in this example, i.e.,
= 1.0. The results of these computations are given in Table 3-4 followed by examples and explanations.
Column 1 of Table 3-4 is the distance in nautical miles measured
seaward of the entrance to Chesapeake Bay, using incréments of 5 nautical
miles for each section.
Column 2, dæ, is the depth in feet referred to mean low water at the
shoreward end of each section, denoted by X of Column 1.
Column 3 is
the depth dj at the beginning of each section.
Column 4 is the depth d2 at the shoreward end of each section.
These depths are the water depths below MLW plus the 2.5-foot astronomical tide plus the hurricane surge and are then rounded off to the
nearest foot.
Column 5, dy, is the average of Columns 3 and 4 to the nearest foot.
Column 6 is the effective fetch F&
obtained for the first step directly from
steps, Fe = Fg + AF < 137 n.mi. where te
above in each case (e.g., line X - 40, Fe
5 n.mi. Fg is defined for Column 14.
(nautical miles), and is
Equation 3-40. For successive
is given in Column 14 one line
= 80.6 + 5.0 = 85.6) and AF is
3-65
to 220 nautical miles as determined from Figure 3-15 for
= 91.6,
= 59.4 can be used with the deepwater forecasting curves, or else
Equation 3-40 can be used, as modified,
H = 0.0555 UR Jf' + AF
O
K.
y e
along with Equation 3-36
To = 2-13
•
Fg is defined below.
The latter being a numerical method is easier to use and more accurate
than the graphical method of using forecasting curves.
The procedure for computing wind waves over the Continental Shelf
will be illustrated by using the bottom profile off the mouth of the
Chesapeake Bay and the standard project hurricane developed for the
Norfolk area. The storm surge computed for the standard project hurricane
and 2.5 feet of astronomical tide are added to the mean low water depths
to obtain the total water depth for wave génération. Refraction is
neglected in this example, i.e.,
= 1.0. The results of these computations are given in Table 3-4 followed by examples and explanations.
Column 1 of Table 3-4 is the distance in nautical miles measured
seaward of the entrance to Chesapeake Bay, using incréments of 5 nautical
miles for each section.
Column 2, dæ, is the depth in feet referred to mean low water at the
shoreward end of each section, denoted by X of Column 1.
Column 3 is
the depth dj at the beginning of each section.
Column 4 is the depth d2 at the shoreward end of each section.
These depths are the water depths below MLW plus the 2.5-foot astronomical tide plus the hurricane surge and are then rounded off to the
nearest foot.
Column 5, dy, is the average of Columns 3 and 4 to the nearest foot.
Column 6 is the effective fetch F&
obtained for the first step directly from
steps, Fe = Fg + AF < 137 n.mi. where te
above in each case (e.g., line X - 40, Fe
5 n.mi. Fg is defined for Column 14.
(nautical miles), and is
Equation 3-40. For successive
is given in Column 14 one line
= 80.6 + 5.0 = 85.6) and AF is
3-65