Long shore transport along the coasts of sefid roud mouth

Some indicators of the transport rate toward the eastern coast of the mouth (right-hand side) of sefid roud mouth, are the growth of a spit shoaling pattern and deposition rates on the right – hand side which is the result of the long shore transport across the mouth of sefid roud which deflecting the sediments discharged from estuary toward the right coast of the mouth to form sever long shore sand bars in this coastal zone between the mouth of sefid roud and Bander Kia -Shahr.The long shore energy flux in the surf zone is approximated by assuming conservation of energy flux in shoaling waves, using small – amplitude theory, and then evaluating the energy flux relation at the breaker position, The energy flux per unit length of wave crest, or equivalently the rate at which wave energy is transmitted across a plan of unit width perpendicular to the direction of wave advance. The application of energy flux method on the west east coastline of the mouth of sefid roud, is a reliable method to calculate the long shore transport rate, the locality of the mouth of sefid roud is in an area where stronger winds blow out of the N,NW, W,NE and east, resulting in a deepwater distribution of heights and directions of waves relative to wind directions. The percentage of frequency of these five wave directions represents about 57.4 of all the times.The calculations showed that the long shore transport rates from east to west in the surf zone resulting from wave breaking represents about 2.3 times the transport rates from west to east which showed a net annual transport rate toward the west (o.67*106m3/y).This net transport is very small compared with that transport of the density currents in the surf zone (1.1*109m3/y) which is heading from west to east and the 4.12*109m3/y of freshwater discharging from sefid roud.So, depending on these three factors (density current transport, sefid roud discharges,and the long shore currents); and in particular the first two factors, the direction of the axis of the freshwater plum (heavily loaded with suspended sediments) are variable throughout the year.

کلیدواژه ها:

Long shore current ، sefid roud ، surf zone ، Caspian sea ، sediment transport ، density current