Recent observations (eg, FIGURES 1 & 2) demonstrate that alongshore swashzone currents can be strong. However, there are no field-tested models for alongshore runup velocities.

FIGURE 1: Cable probes and field ADV deployed during the SwashX experiment at Scripps Beach in Fall 2000 to study the vertical and cross-shore structure of swash velocities. The SonTek ADVs accurately measure velocities as close as 0.5 cm above the bed, even when submerged intermittently.

FIGURE 1: Cable probes and field ADV deployed during the SwashX experiment at Scripps Beach in Fall 2000 to study the vertical and cross-shore structure of swash velocities. The SonTek ADVs accurately measure velocities as close as 0.5 cm above the bed, even when submerged intermittently.

Figure 2

FIGURE 2: (A) Mean alongshore currents (arrows) observed in the swash (red), surf (blue), and shoaling (green) regions at the elevation above the bed of each sensor, and (B) water depth versus cross-shore distance. Arrows pointing offshore (onshore) represent alongshore currents to the south (north).

Specific objectives for NCEX swash studies include

  • determining the magnitude and structure of alongshore swashzone currents.
  • testing models of alongshore swashzone currents with field observations.
  • examining the range of model validity near regions of large alongshore
    gradients of wave height and direction.
Figure 3

FIGURE 3: Beach profile and NCEX instrument locations.

The research plan for NCEX swash studies will include measuring swash and surfzone velocities along a cross-shore transect (FIGURE 3) using 3 sets (separated horizontally) of 2 vertically-stacked small ADV current meters, as well as 5 other ADV current meters. Pressure sensors will be colocated at each instrument station. Surf- and swashzone bathymetry will be measured using a GPS system and a sonar mounted on a jet ski.