Sediment Transport along the Coast of Israel: Examination of Fluorescent Sand Tracers.

The method of labeled natural sand particles was used to study sediment transport along the central Mediterranean coast of Israel. Six portions of 300 kg each were tagged with various fluorescent colors, and distributed at six different locations in the vicinity of the Herzliya Marina. The tagged sand was scattered at the end of autumn, and sampled three times during the winter. Sampling was interrupted in mid-January because of unexpected dredging at the marina canal entrance. The samples were analyzed at the Yigal Allon Kinneret Limnological Laboratory. The wave climate during that time was analyzed using wave data from Ashdod (40 km south). Wave directions measured in Ashdod were corrected to make them applicable to the Herzliya coast, in accordance with suggested directional shift values. Seven wave storms with significant wave heights of over 2.5 m were observed. Two of them clearly indicate a dominant direction from the southwest and two others from the northwest. However, the time durations and the relative angles between the wave directions and the orthogonal to the coast of the storms propagating from the southwest are essentially larger than those arriving from the northwest. The following results were noted: (i) The drift of tagged sand particles correlated to longshore sediment transport at all depths was in a northern direction throughout the field experiment. The longest distance of transport was 5 km over a period of 36 days. (ii) ''Onshore'' sediment transport was present; sand from 15 m depth was found at 8 m depth. (iii) The cross-shore sediment transport carried sand to a depth of 8 m, but no colored sand from shallow water (2-4 m) was found deeper than 8 m. (iv) Although sedimentation at the marina entrance during the experiment was high, only small amounts of tagged sand were found at the entrance. (v) Findings of tagged sand showed the main area of sedimentation to be along the marina's main breakwater. [ABSTRACT FROM AUTHOR]