Perhaps the simplest technique to measuring a beach profile is known as
the "Emery board" method, developed by a famous coastal scientist
named K.O. Emery. As depicted in Figure 1 the apparatus consists of two
stakes connected by a rope of known length (5m or 10m). This length
sets the measurement interval for individual data points along the
profile.
Each stake has a measurement scale which runs from 0 at the
top, down to the bottom of the stake. Either English or Metric units can
be used, although the scientific community is nearly completely
converted to the metric system. If the beach is sloping downward toward
the sea, the observer sights across the top of the seaward board to the
level of the horizon, and determines the distance (a) from the top of the
landward board to the sightline. If the beach is locally sloping upward in
the offshore direction, then (a) is measured on the seaward board and
the sighting is with the horizon over the top of the landward board. In
either case, the measured distance (a) is equal to the distance (b) that
the beach has either dropped or risen within the horizontal distance
between the boards (the rope length). (Komar, 1998) This approach may seem simple, but it provides reasonably accurate
measurements of beach profiles. It also has the advantages of light, inexpensive, equipment, which can be easily carried to distant
survey sites, for very rapid surveys.
Perhaps the simplest technique to measuring a beach profile is known as
the "Emery board" method, developed by a famous coastal scientist
named K.O. Emery. As depicted in Figure 1 the apparatus consists of two
stakes connected by a rope of known length (5m or 10m). This length
sets the measurement interval for individual data points along the
profile.
Each stake has a measurement scale which runs from 0 at the
top, down to the bottom of the stake. Either English or Metric units can
be used, although the scientific community is nearly completely
converted to the metric system. If the beach is sloping downward toward
the sea, the observer sights across the top of the seaward board to the
level of the horizon, and determines the distance (a) from the top of the
landward board to the sightline. If the beach is locally sloping upward in
the offshore direction, then (a) is measured on the seaward board and
the sighting is with the horizon over the top of the landward board. In
either case, the measured distance (a) is equal to the distance (b) that
the beach has either dropped or risen within the horizontal distance
between the boards (the rope length). (Komar, 1998) This approach may seem simple, but it provides reasonably accurate
measurements of beach profiles. It also has the advantages of light, inexpensive, equipment, which can be easily carried to distant
survey sites, for very rapid surveys.
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Perhaps the simplest technique to measuring a beach profile is known as
the "Emery board" method, developed by a famous coastal scientist
named K.O. Emery. As depicted in Figure 1 the apparatus consists of two
stakes connected by a rope of known length (5m or 10m). This length
sets the measurement interval for individual data points along the
profile.
Each stake has a measurement scale which runs from 0 at the
top, down to the bottom of the stake. Either English or Metric units can
be used, although the scientific community is nearly completely
converted to the metric system. If the beach is sloping downward toward
the sea, the observer sights across the top of the seaward board to the
level of the horizon, and determines the distance (a) from the top of the
landward board to the sightline. If the beach is locally sloping upward in
the offshore direction, then (a) is measured on the seaward board and
the sighting is with the horizon over the top of the landward board. In
either case, the measured distance (a) is equal to the distance (b) that
the beach has either dropped or risen within the horizontal distance
between the boards (the rope length). (Komar, 1998) This approach may seem simple, but it provides reasonably accurate
measurements of beach profiles. It also has the advantages of light, inexpensive, equipment, which can be easily carried to distant
survey sites, for very rapid surveys.
การแปล กรุณารอสักครู่..