Equation 3-49 provides a conservative estimate for wave setup at the
shore. The différence between laboratory data and theory, however is not
likely to exceed the uncertainties of field data.
************** EXAMPLE PROBLEM **************
GIVEN: Hb = 20 feet, T = 12 seconds
FIND: Wave setup, Sy<
SOLUTION: Using Equation 3-49
% = 0.19 1-2.82 —
Hb>
= 0.19
/
20
V4
1-2.82 ------------ -
\32.2(12)2/
20 ,
S— 3.1feet. Say 3 feet.
Equation 3-49 is only applicable to normal beach slopes.
*************************************
3.86 STORM SURGE AND WIND SETUP
3.861 General. Reliable estimâtes of water-level changes under storm
conditions are essential for the planning and design of Coastal engineering works. Détermination of design water élévations during storms is a
complex problem involving interaction between wind and water, différences
in atmospheric pressure, and effects caused by other mechanisms unrelated
to the storm. Winds are responsible for the largest changes in water
level when considering only the storm-surge generating processes. A wind
blowing over a body of water exerts a horizontal force on the water surface
and induces a surface current in the general direction of the wind. The
force of wind on the water is partly due to inequalities of air pressures
on the windward side of gravity waves, and partly due to shearing stresses
at the water surface. Horizontal currents induced by the wind are impeded
in shallow water areas, thus causing the water level to rise downwind
while at the windward side the water level falls. The term storm surge is
used to indicate departure from normal water level due to the action of
storms. The term wind setup is often used to indicate rises in lakes,
Sn?ller bodies of water. A fall of water level below the
Tetdown
UPWinÜ Side °f a basin is §enerally referred to as
coastS^rZven°M^VrwdUCe S^ges in.excess of 25 feet on the open
and réservoirs are
a?j estuaries. Generally, setups in lakes
équivalent to the setun* a^.^etdown ln these enclosed basins is about
the volume of
P’. S®tdown in °Pen océans is insignificant because
of the coast is
produce the setuP al°ng the shallow régions
ever setdoLn Lv h
comPared to the volume of water in the océan. Hower, setdown may be appréciable when a storm traverses a relatively narre»
3-82
shore. The différence between laboratory data and theory, however is not
likely to exceed the uncertainties of field data.
************** EXAMPLE PROBLEM **************
GIVEN: Hb = 20 feet, T = 12 seconds
FIND: Wave setup, Sy<
SOLUTION: Using Equation 3-49
% = 0.19 1-2.82 —
Hb>
= 0.19
/
20
V4
1-2.82 ------------ -
\32.2(12)2/
20 ,
S— 3.1feet. Say 3 feet.
Equation 3-49 is only applicable to normal beach slopes.
*************************************
3.86 STORM SURGE AND WIND SETUP
3.861 General. Reliable estimâtes of water-level changes under storm
conditions are essential for the planning and design of Coastal engineering works. Détermination of design water élévations during storms is a
complex problem involving interaction between wind and water, différences
in atmospheric pressure, and effects caused by other mechanisms unrelated
to the storm. Winds are responsible for the largest changes in water
level when considering only the storm-surge generating processes. A wind
blowing over a body of water exerts a horizontal force on the water surface
and induces a surface current in the general direction of the wind. The
force of wind on the water is partly due to inequalities of air pressures
on the windward side of gravity waves, and partly due to shearing stresses
at the water surface. Horizontal currents induced by the wind are impeded
in shallow water areas, thus causing the water level to rise downwind
while at the windward side the water level falls. The term storm surge is
used to indicate departure from normal water level due to the action of
storms. The term wind setup is often used to indicate rises in lakes,
Sn?ller bodies of water. A fall of water level below the
Tetdown
UPWinÜ Side °f a basin is §enerally referred to as
coastS^rZven°M^VrwdUCe S^ges in.excess of 25 feet on the open
and réservoirs are
a?j estuaries. Generally, setups in lakes
équivalent to the setun* a^.^etdown ln these enclosed basins is about
the volume of
P’. S®tdown in °Pen océans is insignificant because
of the coast is
produce the setuP al°ng the shallow régions
ever setdoLn Lv h
comPared to the volume of water in the océan. Hower, setdown may be appréciable when a storm traverses a relatively narre»
3-82