# Fall 2001Quiz 1c

A wave with a period T=6.1 seconds, a deep water height Ho=1.4 m, and a deep water angle of attack ao=41° moves into water with depth D= 4.2 m.  You 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=  6.10 sec        Ho=  1.40 m  &   Alpha-o=  41.0

then at  d=  4.20 m

Lo= 1.56 * T^2=   58.05 m        Co= Lo/T = 1.56 * T =    9.52 m/sec

d / Lo =   0.0724

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.1150    0.0711    0.6180    0.9690

L=   36.52 m   &  C=    5.99 m/sec using L= d / (d/L) & C = L/T

L=   35.87 m   &  C=    5.88 m/sec using L = Lo * tanh & C=L/T

H= Ks * Ho =  1.36 m   (if no refraction)

alpha1=   24.38  using alpha = arcsin( C / Co * sin(alphao))

alpha1=   23.92  using alpha = arcsin(tanh * sin(alphao))

Kr=    0.91 using Kr=sqrt(cos(alphao)/cos(alpha))

H =    1.23 m    using Ho*Kr*Ks

H/d=    0.29

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)  You have a house being threatened by coastal erosion.  In general terms, what can be done about the problem?

(3) How can coastlines be classified in terms of plate tectonics?

(3) Discuss two ways geology affects the features found on a coastline.

# Fall 2001Quiz 1a

A wave with a period T=7.3 seconds, a deep water height Ho=1.6 m, and a deep water angle of attack ao=39° moves into water with depth D= 3.1 m.  You 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=  7.30 sec        Ho=  1.60 m  &   Alpha-o=  39.0

then at  d=  3.10 m

Lo= 1.56 * T^2=   83.13 m        Co= Lo/T = 1.56 * T =   11.39 m/sec

d / Lo =   0.0373

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.0800    0.0371    0.4640    1.0790

L=   38.75 m   &  C=    5.31 m/sec using L= d / (d/L) & C = L/T

L=   38.57 m   &  C=    5.28 m/sec using L = Lo * tanh & C=L/T

H= Ks * Ho =  1.73 m   (if no refraction)

alpha1=   17.06  using alpha = arcsin( C / Co * sin(alphao))

alpha1=   16.98  using alpha = arcsin(tanh * sin(alphao))

Kr=    0.90 using Kr=sqrt(cos(alphao)/cos(alpha))

H =    1.56 m    using Ho*Kr*Ks

H/d=    0.50

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)  You have a house being threatened by coastal erosion.  In general terms, what can be done about the problem?

(3) How can coastlines be classified in terms of plate tectonics?

# Fall 2001Quiz 1b

A wave with a period T=9.1 seconds, a deep water height Ho=2.1 m, and a deep water angle of attack ao=37° moves into water with depth D= 6.1 m.  You 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=  9.10 sec        Ho=  2.10 m    &   Alpha-o=  37.0ø

then at  d=  6.10 m

Lo= 1.56 * T^2=  129.18 m        Co= Lo/T = 1.56 * T =   14.20 m/sec

d / Lo =   0.0472

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.0900    0.0461    0.5120    1.0370

L=   67.78 m   &  C=    7.45 m/sec using L= d / (d/L) & C = L/T

L=   66.14 m   &  C=    7.27 m/sec using L = Lo * tanh & C=L/T

H= Ks * Ho =  2.18 m   (if no refraction)

alpha1=   18.41  using alpha = arcsin( C / Co * sin(alphao))

alpha1=   17.95  using alpha = arcsin(tanh * sin(alphao))

Kr=    0.92 using Kr=sqrt(cos(alphao)/cos(alpha))

H =    2.00 m    using Ho*Kr*Ks

H/d=    0.33

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)  You have a house being threatened by coastal erosion.  In general terms, what can be done about the problem?

(3) How can coastlines be classified in terms of plate tectonics?