الفهرس 
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Abstract
The sediments along the studied locality may be affected by the water
currents as well as hydro-morphologic features. The studied locality can be
divided into two main geographic parts (southern and northern). The southern
geographic part is characterized by its sinuosity, relatively narrow width,
shallow depth and narrow cross sectional area. However, the northern
geographic part is characterized by its low sinuosity, wide surface, deep bottom
and its large cross sectional area.
The western bank mostly slopes gently relative to the eastern bank. The
deepest points along the studied locality mainly exist in the eastern side. There
is a wide spread of rocky irregularities and ridges along the northern part.
The width increases northward from 360 m at profile 23 to reach about
9800 m at profile 22. The depth gradually increased from 10.5 m at profile 23 to
reach 36 m at profile 22. The profile areas increased northward from 2940 m2 to
reach about 217200 m2 at profile 22.
The interaction between sediments and water is mainly controlled by
temperature, current regime, pH, total dissolved salts and the dissolved nutrient
salts concentration. The air temperature was higher than the water temperature.
Along the southern part, there was no variation in water temperature and total
dissolved salts between the surface and the bottom, (i.e.) one water mass.
Whereas, the downward decrease in temperature was established along the
northern part that may be referred to the width of the channel as well as the
depth.
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Along the studied locality, the current velocity decreases with increasing
the profile area. Therefore, it decreased northward from values reached 87
cm/sec at profile 23 to values as low as 2 cm/sec at profile 22. The pH values
varied between 7.33 (slightly alkaline) and 8.55 (moderately alkaline). Along
the southern geographic part, the pH values slightly increased northward from
7.43 at profile 23, to 7.72 at profile 19 with nearly no vertical variation. North
of profile 19, there was nearly no change in pH values till the end of this part.
Along the northern geographic part, the vertical variation in pH values was
established, whereas the average pH values increased northward from 7.74 to
reach 8.2. The electrical conductivity mainly tends to increase northward due to
evaporation, consequently, increases the total dissolved salts. The total
dissolved salts ranged between 131 mg/l and 169 mg/l with corresponding
electrical conductivity values ranged between 204 and 264 μmohs/cm
respectively. Along the southern geographic part, the average values of total
dissolved salts tended to decrease northward ranging between 131 mg/l and 156
mg/l. Along the northern geographic part, the average values of total dissolved
salts increased northward to reach 165 mg/l at profile 22. The factors controlled
total dissolved salts are the hydromorphologic features as will as the nutrient
salts concentration. The nutrient salts are represented by Silicates (SiO2)
Phosphates (PO4) Nitrates (NO3
-) and Nitrites (NO2) where silicates formed the
main constituent. The total nutrient salts tended to decrease northward ranging
between 7.71 mg/l and 20 mg/l.
Water as a medium transports sediments from the upstream to the lake and
from adjacent territories. Recent sediments in the studied locality include two
main constituents, the suspended matter and the sediments laden on the bottom.
The suspended matters increased downward, as well, it intensively decreased
northward from 915 mg/l to reach 7 mg/l.
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On the bases of the average distribution of the suspended matters, the area
under investigation may be divided into two main environments, riverine and
lacustrine. The riverine environment located between lat. 21o 2’ 55.35” and 21o
17’ 01.41” and long. 30o 38’ 54.65” and 30o 47’ 12.99”, along which, the average
suspended matters increased northward from 439 mg/l to reach 642 mg/l. The
lacustrine environment located between lat. 21o 17’ 01.41” and 21o 57’ 13.26”
and long. 30o 47’ 12.99” and 31o 18’ 32.99”, may be differentiated into two main
geographic parts, southern and northern. Along the southern part of lacustrine
environment, the average suspended matters showed nearly no change. Along
the northern part of lacustrine environment, the average suspended matters
decreased northward to reach 13 mg/l.
The main factor affecting the suspended matters are the total dissolved
salts, and the current velocities. Along the riverine environment, there was no
distinct relation between suspended matters and total dissolved salts, whereas,
along the southern part of the lacustrine environment, the suspended matters
decreased with decreasing the total dissolved salts. However, along the northern
part of lacustrine environment, the total dissolved salts may assist the
suspended matters to settle due to coagulation, so, the suspended matters
decreased with increasing the total dissolved salts. Along the studied locality,
the suspended matters decreased with increasing each of the profiles width,
depth and area. Along the riverine environment, although, the current velocity
decreased northward, suspended matter increased. Whereas, along the lacustrine
environment, the suspended matter decreased with decreasing the current
velocity.
The riverine environment characterized by sand, silty sand, sandy clay silt,
clay silt and silty clay sediments, whereas, the lacustrine environment is
characterized by silty clay and clay sediments. Sand was found to be restricted
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to riverine environment in which it decreased gradually northward. Silt content
ranged between 1% and 60% with an average 23%. Along the riverine
environment, the average silt content increased northward from 22% to 52%
with an average 38%. Along the lacustrine environment, the average silt content
decreased northward to reach 12% with an average 19%. The clay content
ranged between zero % and 78% with an average 60%. The average clay
content regionally increased northward. Along the riverine environment, the
average clay content increased northward from 11% to 39% with an average
25%. Along the lacustrine environment, the average clay content continued to
increase northward to reach 73% with an average 69%. The colloidal materials
ranged between 0% and 19% with an average 11%. The average colloidal
materials regionally increased northward (i.e.) reflecting its relation to clay.
Along the riverine environment, the average colloid content increased from 1%
to 6% with an average 4%. Along the lacustrine environment, the average
content increased to reach 15% with an average 12%.
The median diameter (MdØ) ranges between 2.08Ø (fine sand) and 11.40Ø
(very fine clay) with an average 9.46Ø (medium clay). Along the riverine
environment, the average values of MdØ increased northward from 3.86Ø (very
fine sand) to 7.68Ø (very fine silt) with an average 5.8Ø (medium silt). Along
the lacustrine environment, the values continued to increase northward to reach
10.92Ø (fine clay). It has an average 10.37Ø (fine clay). The mean size (MzØ)
ranged between 2.11Ø (fine sand) and 11.26Ø (very fine clay) with an average
9.27Ø (medium clay). Along the riverine environment, the average values of
MzØ increased northward from 4.06Ø (coarse silt) to 8.09Ø (coarse clay) with
an average 6.14Ø (fine silt). Along the lacustrine environment, the average
values of MzØ continued to increase northward reaching 10.49Ø (fine clay)
with an average 10.05Ø (fine clay). In the riverine environment, the mean size
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MzØ exceeded the median diameter MdØ whereas the median diameter MdØ
exceeded the mean size MzØ in the lacustrine environment. The inclusive
sorting σI ranged between 0.62 (moderately sorted) and 3.39 (very poorly
sorted) with an average 1.91 (poorly sorted). Along the riverine environment,
the average value of inclusive sorting σI increased northward from 1.3 (poorly
sorted) to 2.55 (very poorly sorted) with an average 2.16 (very poorly sorted).
Along the lacustrine environment, the average values of the inclusive sorting σI
decreased northward to reach 1.71 (poorly sorted) with an average 1.85 (poorly
sorted). The skewness SkI ranged between -0.45 (strongly coarse skewed) and
0.39 (strongly fine skewed) with an average -0.18 (coarse skewed). Along the
riverine environment, the average value of skewness SkI is slightly increased
northward, (i.e.), the sediments tend to skewed toward the fine fraction. Along
the lacustrine environment, the average values of skewness decreased
northward (i.e.) the sediments tend to skewed towards the coarse fraction. The
Kurtosis KG ranged between 0.66 (very platykurtic) and 1.60 (very
Leptokurtic) with an average 0.96 (mesokurtic). Along the riverine
environment, the average values of Kurtosis KG decreased northward from 0.91
(mesokurtic) to 0.73 (platykurtic) with an average 0.88 (platykurtic). Along the
lacustrine environment, the average values Kurtosis KG increased northward to
reach 1.26 (leptokurtic) with an average 0.98 (mesokurtic).
The main factor affecting the sediments distribution along the studied
locality is the current velocity (especially along the lacustrine environment)
that, in turn, affected with the hydromorphologic features.
Along the studied locality, there are two main mechanisms of deposition,
river processes (in the riverine environment) and slow depositional processes
from quiet water (in the lacustrine environment).
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The organic matter content in bottom sediments increased northward
where it ranged between 1.26% and 12.78% with an average 9.71%. Along the
studied locality, the organic matter content increased with decreasing the grain
size of the sediments. i.e., the area under investigation is characterized by fine
grain sediments contained organic matter, concentrated in the lacustrine
environment.
The carbonate content ranged between 5.05 % and 8.02% with an average
6.54 %. Along the riverine environment, the average distribution of carbonate
content increased northward, whereas, it decreased along the southern part of
the lacustrine environment. Along the northern part of the lacustrine
environment, the carbonate content increased northward.
Along each of the riverine environment and the northern part of the
lacustrine environment, the carbonate content increases with decreasing each of
the grain size and organic matter content. Wherever, there was a reverse
relation along the southern part of the lacustrine environment. Along the studied
locality, the carbonate content increases in the sediments with increasing the pH
of water.
X-ray diffraction analysis reflected that the bottom sediments composed
mainly of clay minerals including Momtmorillonite, Kaolinite and Illite in
addition to Quartz, Feldspar, Calcite and Hematite. Quartz showed its
maximum content at the riverine environment. Along the southern part of the
lacustrine environment, the quartz content decreased northward. Along the
northern part of the lacustrine environment, the quartz content showed nearly
no change. The feldspar showed its maximum content at the riverine
environment, whereas, there is no change in its content along the lacustrine
environment. The calcite content showed relatively lower values along the
riverine environment compared with the southern part of the lacustrine
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environment. Along the northern part of the lacustrine environment, the calcite
content increased northward. The hematite shows its maximum content in the
riverine environment, whereas, it decreased northward along the lacustrine
environment.