Spring 2001   Quiz 1b

A wave with a period T=8.4 seconds, a deep water height Ho=1.5 m, and a deep water angle of attack ao=0° moves into water with depth D=8.8 m.  You will do all calculations at this new depth and not deep water.

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

(2) Determine if the wave is deep, shallow or intermediate at this depth. (Method counts)

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

(2) Will the have broken before it reaches this depth? (Method counts)

Given:  T=  8.40 sec        Ho=  1.50 m    then at  d=  8.80 m

Lo= 1.56 * T^2=  110.07 m        Co= Lo/T = 1.56 * T =   13.10 m/sec

d / Lo =   0.0799

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.1250    0.0820    0.6560    0.9520

So at  d=  8.50 m

L=   70.40 m   &  C=    8.38 m/sec using L= d / (d/L) & C = L/T

L=   72.21 m   &  C=    8.60 m/sec using L = Lo * tanh & C=L/T

H= Ks * Ho =  1.43 m   (if no refraction)

H/d=    0.16

Breaks:  FALSE   (if H/D > 0.78)

(3) You observe the following vertical sequence of sediment along a coastline:

 Marsh mud on top Lagoon mud Beach sand Offshore mud at the bottom

What sequence of events could have created this series of deposits?

(4)  In the coastal classification scheme recommended by the textbook, how do we classify the U.S. West Coast?  What causes this type of coast, and describe 4 common features found along it?

Spring 2001   Quiz 1a

A wave with a period T=8.1 seconds, a deep water height Ho=1.4 m, and a deep water angle of attack ao=0° moves into water with depth D=8.2 m.  You will do all calculations at this new depth and not deep water.

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

(2) Determine if the wave is deep, shallow or intermediate at this depth. (Method counts)

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

(2) Will the have broken before it reaches this depth? (Method counts)

Given:  T=  8.10 sec        Ho=  1.40 m    then at  d=  8.20 m

Lo= 1.56 * T^2=  102.35 m        Co= Lo/T = 1.56 * T =   12.64 m/sec

d / Lo =   0.0801

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.1250    0.0820    0.6560    0.9520

So at  d=  8.20 m

L=   65.60 m   &  C=    8.10 m/sec using L= d / (d/L) & C = L/T

L=   67.14 m   &  C=    8.29 m/sec using L = Lo * tanh & C=L/T

H= Ks * Ho =  1.33 m   (if no refraction)

H/d=    0.16

Breaks:  FALSE   (if H/D > 0.78)

(3) You observe the following vertical sequence of sediment along a coastline:

 Offshore mud on top Beach sand Lagoon mud Marsh mud at the bottom

What sequence of events could have created this series of deposits?

(4)  In the coastal classification scheme recommended by the textbook, how do we classify the U.S. East Coast?  What causes this type of coast, and describe 4 common features found along it?

Spring 2001   Quiz 2b

A wave with a period T=6.3 seconds, a deep water height Ho=1.1 m, and a deep water angle of attack ao=32° moves into water with depth D= 2.6 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=  6.30 sec        Ho=  1.10 m     &   Alpha-o=  32.0

then at  d=  2.60 m

Lo= 1.56 * T^2=   61.92 m        Co= Lo/T = 1.56 * T =    9.83 m/sec

d / Lo =   0.0420

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.0850    0.0415    0.4880    1.0570

L=   30.59 m   &  C=    4.86 m/sec using L= d / (d/L) & C = L/T

L=   30.22 m   &  C=    4.80 m/sec using L = Lo * tanh & C=L/T

alpha1=   15.18  using alpha = arcsin( C / Co * sin(alphao))

alpha1=   14.99  using alpha = arcsin(tanh * sin(alphao))

Kr=    0.94 using Kr=sqrt(cos(alphao)/cos(alpha))

H =    1.09 m    using Ho*Kr*Ks

H/d=    0.42

Breaks:  FALSE   (if H/D > 0.78)

(3) Discuss the relationship between beach slope and breaker type, and why this relationship exits.

(3) Discuss two differences between Airy and Stokes wave theories, and how they apply to the nearshore.

(3) We discussed two types of "black" sand on beaches.  Differentiate them.

Spring 2001   Quiz 2a

A wave with a period T=6.8 seconds, a deep water height Ho=1.3 m, and a deep water angle of attack ao=35° 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=  6.80 sec        Ho=  1.30 m     &   Alpha-o=  35.0

then at  d=  3.10 m

Lo= 1.56 * T^2=   72.13 m        Co= Lo/T = 1.56 * T =   10.61 m/sec

d / Lo =   0.0430

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.0875    0.0438    0.5000    1.0470

L=   35.43 m   &  C=    5.21 m/sec using L= d / (d/L) & C = L/T

L=   36.07 m   &  C=    5.30 m/sec using L = Lo * tanh & C=L/T

alpha1=   16.36  using alpha = arcsin( C / Co * sin(alphao))

alpha1=   16.67  using alpha = arcsin(tanh * sin(alphao))

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

H =    1.26 m    using Ho*Kr*Ks

H/d=    0.41

Breaks:  FALSE   (if H/D > 0.78)

(3) Discuss the relationship between beach slope and breaker type, and why this relationship exits.

(3) What is the most common mineral on continental beaches, and why is it abundant?

(3) Discuss two differences between Airy and Stokes wave theories, and how they apply to the nearshore.

Spring 2001   Quiz 3a

A wave with a period T=8.2 seconds, a deep water height Ho=1.8 m, and a deep water angle of attack ao=39° moves into water with depth D= 2.9 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=  8.20 sec        Ho=  1.80 m    &   Alpha-o=  39.0ø

then at  d=  2.90 m

Lo= 1.56 * T^2=  104.89 m        Co= Lo/T = 1.56 * T =   12.79 m/sec

d / Lo =   0.0276

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.0675    0.0270    0.4000    1.1500

L=   42.96 m   &  C=    5.24 m/sec using L= d / (d/L) & C = L/T

L=   41.96 m   &  C=    5.12 m/sec using L = Lo * tanh & C=L/T

alpha1=   14.94  using alpha = arcsin( C / Co * sin(alphao))

alpha1=   14.58  using alpha = arcsin(tanh * sin(alphao))

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

H =    1.85 m    using Ho*Kr*Ks

H/d=    0.64

Breaks:  FALSE   (if H/D > 0.78)

(3) Discuss how waves, slope, and sediment size relate on the reflective to dissipative beach classification continuum.

(3)  What is sediment sorting, what causes it to occur, and why is it important?

(3) Is the correct equation Kr=Ö (bo/b) or Kr=Ö (b/bo), and why can you say this?  (b is orthogonal spacing)

Spring 2001   Quiz 3b

A wave with a period T=6.9 seconds, a deep water height Ho=1.3 m, and a deep water angle of attack ao=41° moves into water with depth D= 3.3 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=  6.90 sec        Ho=  1.30 m     &   Alpha-o=  41.0

then at  d=  3.30 m

Lo= 1.56 * T^2=   74.27 m        Co= Lo/T = 1.56 * T =   10.76 m/sec

d / Lo =   0.0444

d/L       d/Lo      tanh    H/Ho(Ks)

Table values:  0.0875    0.0438    0.5000    1.0470

L=   37.71 m   &  C=    5.47 m/sec using L= d / (d/L) & C = L/T

L=   37.14 m   &  C=    5.38 m/sec using L = Lo * tanh & C=L/T

alpha1=   19.46  using alpha = arcsin( C / Co * sin(alphao))

alpha1=   19.15  using alpha = arcsin(tanh * sin(alphao))

Kr=    0.89 using Kr=sqrt(cos(alphao)/cos(alpha))

H =    1.22 m    using Ho*Kr*Ks

H/d=    0.37

Breaks:  FALSE   (if H/D > 0.78)

(3) Discuss how waves, slope, and sediment size relate on the reflective to dissipative beach classification continuum.

(3)  What is sediment sorting, what causes it to occur, and why is it important?

(3) Is the correct equation Kr=Ö (bo/b) or Kr=Ö (b/bo), and why can you say this?  (b is orthogonal spacing)