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International Journal of Marine Science 2013, Vol.3, No.32, 253-257
http://ijms.sophiapublisher.com
255
Table 1 The sediment grain size mean of sampled points
Grain size (backshore) mm
Grain size mean (Beach) mm
Grain size mean (Mouth) mm
Name of River
0.014
0.3
0.22
Gorganroud
0.25
0.21
0.15
Nekaroud
0.17
0.3
0.25
Larim
0.22
0.36
0.41
Sorkhroud
0.38
0.25
2.73
Nashtaroud
0.23
0.2
0.21
Sefidroud
1.35
1.42
1.61
Shafaroud
2.28
1.55
2.18
Lisar
with fine to medium or coarse sand in the central of
Mazandaran and Gilan coasts (Sorkhroud, Sefidroud,
and Nekaroud Rivers). Also the comparing results of
sediment size of rivers mouth and surrounded beaches
determined that there is much dissimilarity between
coastal sediments and estuary. For instance: in the
Sefidroud estuary, all sediments in the beach belong to
rivers and it could be covered vast area of beach zone.
At the other hand shore sediments of the Caspian Sea
have covered the rivers mouth in the Nekaroud and
Larim Rivers. But there are transition condition near
to Sorkhroud and Nashtaroud rivers that sea and rivers
sediments cover the coastal zone together.
2.3 Estuary shape classification
On the basis of obtained results of field monitoring
and satellite image analysis the rivers mouth of study
area have been classified to the kind of barred,
swollen, widen, inclination, tighten, deltaic and non
deltaic estuaries (Figure 2). The rivers of south eastern
of the Caspian Sea in the Gomishan-Badar e Turkmen
Figure 2 the Variety of Rivers mouth shape in the study area
Note: a: inclined mouth, b: tighten mouth, c: widen mouth, d:
barred mouth, e: deltaic mouth, f: inflation mouth
and in the central part of Gilan coasts (Gorganroud
and Sefidroud rivers) have certain developed delta.
Instead of there is no delta in the West of Mazandaran
and West of Gilan beach zones (Nashtaroud, Lisar and
Shafaroud rivers. The traits of Rivers of central of
Mazandaran have been inclined near to shore
(Nekaroud and Larim Rivers). Also some mouths of
rivers of West of Mazandaran and Gilan have been
barred with fluvial coarse grain sediments (Nashtaroud,
Lisar and shafaroud Rivers). And many of them have
been widen in the central part of Mazandaran coasts
(Larim Rivers).
2.4 Rapid sea level fluctuation and estuary deformation
Satellite images periodic comparing results show that
the last sea level rose as 2.5 m elevation from 1984 till
2005 could be change the estuary condition and mouth
of rivers shape in the study area. As related to
steepness of beach and kind of sediments covering in
the determined morphological zones, the shape of
mouth of rivers has been changed at the different
types. For instance territory of Gorganroud and
Sefidroud Rivers near to beach zone have been limited
by sea level progression. Also the rapid penetration
of sea water to rivers has caused the several
morphodynamic formation changing (widen and
displacement of mouths). And in the other part of
study area kind of estuary response is different and
wider mouth could be observed on there. For instance
in the Nekaroud estuary territory the mouth of river
was displaced toward beach about 135 meters and the
wide of mouth is increased along the sea level rise
(Figure 3). Of course in the high steepness beach zone
like Sorkhroud shore, the river territory could not be
affected by sea level raised.
3 Discussion
Major coastal sediments of the study area were
originated from the rivers, among them Sefidroud,