SO422 Fall 2005   Quiz 1

20 points total

 

           A wave with a period T=8.7 seconds, a deep water height Ho=1.6 m, and a deep water angle of attack ao=27 moves into water with depth D= 3.6 mYou will do all calculations at this new depth and not deep water.

(5) Calculate the speed and wavelength of the wave at this depth (not in deep water).

(3) By how much will the wave have refracted when it reaches this depth?

(3) What will be the height of the wave at this depth (not in deep water)?

 

 Given: T= 8.70 sec Ho= 1.60 m & Alpha-o= 27.0

then at d= 3.60 m

Lo= 1.56 * T^2= 118.08 m Co= Lo/T = 1.56 * T = 13.57 m/sec
d / Lo = 0.0305

                        d/L      d/Lo     tanh    H/Ho(Ks)
Table values: 0.0725 0.0309 0.4260 1.1190

L= 49.66 m & C= 5.71 m/sec using L= d / (d/L) & C = L/T
L= 50.30 m & C= 5.78 m/sec using L = Lo * tanh & C=L/T
H= Ks * Ho = 1.79 m (if no refraction)
alpha1= 11.01 using alpha = arcsin( C / Co * sin(alphao))
alpha1= 11.15 using alpha = arcsin(tanh * sin(alphao))
Kr= 0.95 using Kr=sqrt(cos(alphao)/cos(alpha))
H = 1.71 m using Ho*Kr*Ks
H/d= 0.47
Breaks: FALSE (if H/D > 0.78)

 


You should answer these questions with about 3 sentences.  You can use bullet format, but for full credit must clearly describe what you mean.

(3)  Why can the coast be considered to be in dynamic equilibrium, and how does hurricane Katrina fit into this model?

(3) List the three main categories of coastlines in terms of plate tectonics, and the major types of features found on two of them.

(3) Whats the most common mineral on beaches, and why is this the case?  Discuss two other minerals you might find, and the conditions under which they could occur.