Cress Help -Water levels - Z1 -

Wind set-up 

Calculation of water level as a function of fetch length, water depth and wind speed. As extra parameters the approach angle towards the coast can be entered.
The calculation is carried out in two steps. In the first step the rise in the deeper section is calculated. in the second step the calculation in a shallow section is calculated.

The calculation is done for either open sea (lake/sea=1) or for a closed lake (lake/sea=3).

Constants and parameters

Included in the routine are the following constants:

rair = 1.21 kg/m3

rwater = 1030 kg/m3  

The friction factor cw varies acc. to Karelse and Van Os [1979] between 0.8*10-3 and 3*10-3. In this routine by default 2*10-2 is used.

Equations used

                        (equation 1)

For open sea:

        (equation 2)

in which:

For a closed lake the same equation is used, without the value 0.5

For the shallow part for open sea the same equation is used, but using different values for h and F (depth of shallow section and width of shallow section).

For closed area the following equation is used (from: Leidraad Rivierdijken II; equation is valid for h/F <0.001):

       (equation 3)

in which F is the local fetch (= width of the shallow zone) and h is the depth of the shallow zone.

The total set up is the sum of the deep water set-up and the shallow water set-up.

Special comments:

All combinations of equation 2 and 3 are possible:

lake/sea deep part shallow part
-1 eq 2. using 0.5 eq. 2, using 1.0
0 eq 2, using 1.0 eq. 2, using 1.0
1 eq. 2, using 0.5 eq. 3
2 eq.2, using 1.0 eq. 3
3 eq. 3 eq. 3

References