Environmental Engineering Reference
In-Depth Information
Sampling Site
Water and sediment samples were collected from the
P. Coarctata
bed and its immediate
vicinity of the Fauzderhat region of Chittagong coast for studying hydrological and
pedological factors.
The tidal range of this coast was about 2.43m to 3.04m throughout the year (Talukder,
2004). The area of Fauzdarhat is about 7 km beach situated approximately 20 km southwest
of Chittagong port city. In the classification of sea land boundary or coast, Fauzderhat coast is
under the type ―Ocean front‖ which refers to that part of the sealand boundary zone which is
exposed to the full forces of the open sea (Kinne, 1978). Fauzderhat coastal area is under the
macrotidal range according to the tidal range classification of Lee et al.
,
1985. Tides are
semidiurnal with prominent diurnal effect in the intertidal zone of Fauzderhat coast. The
geographical location of the study site is between latitude 22°23.89' and 22°24.02'N, and
longitude 91°44.59' and 91°44.84'E. The plot area of study site is 50X350m
2
from where
sample had been collected for a total of two years. The area is crisscrossed with one major
tidal creek and eight small tidal creek connected with nine subs and smaller creeks. The mean
width and height of the major tidal creek were 17 and 16.5ft respectively. Average slope of
the major tidal creek was 23%. The mean width and height of the small tidal creek were 14.2
ft and 10ft respectively. The mean width and height of smaller tidal creek were 5.6 ft and 4.2
ft respectively. The sampling site was vegetated by salt marsh plant,
Porteresiacoarctata
with
the average slopes of 4.5% and 1.5% towards the creek and seaward position respectively
(Uddin et al.
,
2010; Abu Hena et al.
,
2010). The unconsolidated soil particle was eroded at a
high rate during rainy season while the percentage of sand is very high rather than silt and
clay. Sedimentation pattern is quite reverse in winter while the percentage of clay is very high
rather than sand and silt. The intermediate level of sand clay was found during premonsoon
and post monsoon of the year.
The sampling site was shown in the Figure 1.
Sampling Duration
Water and sediment samples were collected monthly from the sampling area for a period
of two years from the month of June' 2008 to the month of May'2010.
Sampling Design
Sampling was conducted within a salt-marsh habitat of the inertidal area of Fauzderhat,
Chittagong coast is influenced by the tidal effect of the Bay of Bengal. This salt-marsh is
dominated floristically by
Porteresia Coarctata
(Family: Poaceae).
The genus
Porteresia
resembles Oryza, but differs in the nature of embryo and leaf
anatomy (Clayton and Renvoize,1986): it has an extensive rhizome system similar to that
seen in species of the genus
Spartina
found in temperate salt marshes (Flowers et al.
,
1990).
