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Egyptian Journal of Aquatic Research (2015) 41, 165–176
HO ST E D BYNational Institute of Oceanography and Fisheries
Egyptian Journal of Aquatic Research
http://ees.elsevier.com/ejarwww.sciencedirect.com
FULL LENGTH ARTICLE
Effect of flooding on distribution and mode
of transportation of Lake Nasser sediments, Egypt
* Corresponding author at: Fresh Water and Lakes Division,
National Institute of Oceanography and Fisheries (NIOF), 101 El
Kasr El Eini St., Cairo, Egypt. Tel.: +20 1008616048.
E-mail address: hf_geo@hotmail.com (H.I. Farhat).
Peer review under responsibility of National Institute of Oceanography
and Fisheries.
http://dx.doi.org/10.1016/j.ejar.2015.03.0091687-4285 ª 2015 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Hassan I. Farhat *, Salem G. Salem
Geology Lab., National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
Received 18 January 2015; revised 9 March 2015; accepted 9 March 2015
Available online 28 March 2015
KEYWORDS
Bottom sediment;
Lake Nasser;
Mode of transportation;
Flooding
Abstract Sediment samples have been collected from Lake Nasser during drought and flooding
periods to study the effect of flood season on bottom sediment distribution and mode of transporta-
tion. Ten sectors with three sites in each sector were chosen from upstream of Aswan High Dam to
Adindan. The study showed that Lake Nasser sediments are heterogeneous and are mainly silty clay
and clayey silt. Eastern and western sides of the lake include more sand. Depth controlled dis-
tribution of grain size (deeper is finer). Sands increase with the starting of the flood season.
During drought periods suspension was the most predominant mode of transportation; i.e. sedi-
ments transported by a medium of considerable density. During flooding period siltation and sus-
pension were most predominant modes of transportation; i.e. environment with a high energy,
various overlapping processes, and variety of depositional environments. C–M diagram indicates
that sediments during drought periods behaved as pelagic suspension in which sediments settled
from a suspension in stagnant water, rolling; overbank facies suspension and uniform suspension
were of less importance. During the flooding period there was no clear trend for studied sediments
of pelagic suspension; rolling, graded suspension, overbank facies suspension, suspension, and uni-
form suspension were widely distributed.ª 2015 National Institute of Oceanography and Fisheries. Hosting by Elsevier B.V. This is an open access
article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
Many factors control sedimentation in the High Dam Lakesuch as annual effective base level for each flood, distribution
and characteristics of rocky islands, the valley Lake bends, theold river terraces, and the plankton induced deposition, water
discharges especially during flooding periods, sediment loadsand their gradation. During high water level the influence ofthese factors can be exemplified by the large scale sedimentdeposition at the lake entrance, while during a lower water
profile sediments would mainly deposit further downstream(Aboul-Haggag; 1977; El-Manadely et al., 2002). At lakeentrance (Gomi and the Second Cataract (Abca)) silt layer
was 17 and 20 m respectively. Further downstream it was2 m at Adindan and 1 m at Abu-Simbel within Lake Nasser(Aboul-Haggag, 1977; El Dardir, 1984, 1987). 90% of depos-
ited sediment between 1964 and 1998 is within the Sudaneseside of the reservoir (El-Manadely et al., 2002). Hafez (1977)stated that some microorganisms act as filtering organisms in
166 H.I. Farhat, S.G. Salem
the reservoir which feed on finer materials suspended thendigest the organic content in the fine materials and coagulatethe suspended particles to bigger droplets. These filtering
organisms are believed by Entz and Latif (1974) to be the mainreason for the turbid water not reaching the northern sectionof the reservoir.
Before the construction of the Aswan High Dam the sedi-ments discharged into the Mediterranean Sea, and quantityof these sediments greatly increases at the beginning of Nile
flood. Since 1964, this amount of sediments has been held inthe Aswan High Dam Reservoir (Hurst, 1952). Aswan HighDam acts as a good trap by which; under normal conditions;only the finest fractions of the suspended load are transported
to the downstream. During the flood season 98% of the annualsediment load occurred; (2% in July, 45% in August, 38% inSeptember, 12% in October, and 1.5 in November), Quelennec
and Kruk (1976).Different methods are widely used for determining the
source material of sediments, as well as the environment and
dynamics of their transport and deposition such as: grain-sizedistribution (Mycielska-Dowgiao and Ludwikowska-Kedzia,
Figure 1 A map showing sampling sites of Lake Nasser (General lo
2011; Woronko, 2012; Farhat, 2013), rounding and surfacemorphology of quartz grains in sand and silt (Mycielska-Dowgiao and Woronko, 2004), the petrographical com-
position of the light minerals (Mycielska-Dowgiao, 1995,2007; Woronko et al., 2013), and composition of heavy-min-eral assemblages (Marcinkowski and Mycielska-Dowgiao,
2013). The joint analysis of all previous textural features isthe best method for determining the environment and dynam-ics of their transport and deposition as well as the source mate-
rial of sediments. Each of them provides its own information,which supplements the other data. (Morton et al., 2013;Wachecka-Kotkowska and Lu-dwikowska-Kedzia, 2013).
Distributions of gravel, sand and mud fractions are used as
good indicators for studying of all textural properties of depos-its. Different interpretations of grain size distributions led tonumerous discussions (e.g. Friedman and Sanders, 1978;
Mycielska-Dowgiao, 2007; Flemming, 2007; Hartmann andFlemming, 2007; Szmanda, 2007; Weltje and Prins, 2007;Mycielska-Dowgiao and Ludwikowska Kedzia, 2011). Grain
size depends on several factors such as: transport processes,the sedimentation conditions and transport related features,
cation of Lake Nasser in Egypt is shown in the top left corner).
Effect of flooding on sediments of Lake Nasser 167
all of previous factors are better expressed in the structural fea-tures (Flemming, 2007; Hartmann and Flemming, 2007).
The aim of this study is to show the effect of flood season
on bottom sediments of Lake Nasser, which could help inunderstanding the differences between sediments’ grain sizedistribution and mode of transportation during drought
(DDP) and flooding periods (DFP).
Materials and methods
Area of study
The largest man-made lake in Africa; the High Dam Lake; isformed after the construction of a rock-filled dam on theRiver Nile (17 km south of Aswan, 900 km from Cairo). The
lake extends from the dam itself in the north to the Cataractat Dal, to Sudan in the south. The major portion of the lakelies in Egypt and is known as Lake Nasser and Lake Nubiaon the Sudanese side. Lake Nasser extends between latitudes
22�000–23�580 N and longitudes 31�190–33�190 E (Abou ElElla and El Samman, 2010; Heikal, 2010).
Egypt is classified as a water scarce country, in addition to
an increase in population it is preoccupied with a shortage ofwater resources. The Nile River and Lake Nasser are the prin-cipal arteries of life in Egypt (Flakenmark et al., 1989; Hassan
and Al Rasheedy, 2007). Lake Nasser has a long and narrowshape particularly at its southern part (Lake Nubia), morethan 95% of the Egyptian freshwater budget is coming from
Lake Nasser (El Shemy, 2010).The whole reservoir extends about 496 km, 292 km for
Lake Nasser and 204 km for Lake Nubia. The area of thereservoir at 180 m vertical level is about 6275 km2 of which
Lake Nasser occupies about 5248 km2. The mean depth ofLake Nasser at 160 m vertical level is 21.5 m as compared withabout 25.2 m at 180 m vertical level (Abou El Ella and El
Samman, 2010; El Shemy, 2010).
Geographical and geological settings
Most of the topographic features located in Lake Nasser dateback to the Pliocene, while the present deep gorges and khors
Figure 2 Showing distribution of sand fraction of Lake Nasser sedim
channel, E: eastern bank, W: western bank).
(wadis) together with the relief are probably of the Pleistoceneor Recent age. The channel of old River Nile followed differentdirections starting southward from Wadi Halfa until Aswan
northward. It was divided into Wadi Halfa – Thomas (SW–NE direction) and Thomas – El-Diwan (NW–SE), El-Diwan –Korosko (W–E). North to Korosko, the channel of the old
River Nile followed two directions, (SW–NE) and (SE–NW).Kalabsha High Dam channel followed almost one main trend(S–N) which was controlled by igneous and metamorphic rock
exposures on both sides. Deep canyon with highly slick-sidedis located at El-Madiq area (Issawi, 1968, 1978; Hassan et al.,2010).
The area of Lake Nasser belongs to the so-called Arabo-
Nubian massif. Four main geomorphological and geologicalunits are found which are (1) Aswan Hills extend along theeastern bank of Lake Nasser with rugged topography, (2)
The old Nile valley and the High Dam Reservoir are extendedalong the western edge of Aswan hills. (3) The Nubian Plaincovers most of the low lands west of the old Nile valley.
And (4) The Sinn El–Kaddab Plateau is a vast limestonecapped table land (Issawi, 1968).
Faulting is the most important geologic feature in Lake
Nasser area. The largest faults are Kalabsha and Seiyal faults;trending in E–W direction; with predominant faults in N–Sdirection. NW–SW and NE–SW are subordinate faults. Up-arching is found as a result of uplifting of basement rocks.
Folding is a less predominant structure. Small domes and sev-eral basins were created according to the up-arching of thebasement (Issawi, 1968, 1978; Wycisk, 1987; Morgan, 1990;
Klitzsch and Wycisk, 1999).
Sampling
Sampling was undertaken through a comprehensive programof the National Institute of Oceanography and Fisheries(NIOF) (Fresh Water and Lakes Division-FWLD) in order
to study environmental conditions and Fisheries of LakeNasser. The sampling program was done during 2013.
Sediment samples were collected using Ekman grab samplersemi-annually during drought (DDP) and flooding periods
(DFP) during spring and autumn, 2013. Samples were
ents. DDP: Before flood season, DFP: After flood season (M: main
Figure 3 Showing distribution of mud fraction of Lake Nasser sediments. DDP: Before flood season, DFP: After flood season (M: main
channel, E: eastern bank, W: western bank).
168 H.I. Farhat, S.G. Salem
collected from ten sectors in the main channel of the lake from
south to north; Adindan, Abu-Simbel, Tushka, Amada,Korosko, El-Madiq, Wadi-Abyd, Kalabsha, Dahmit andupstream of High Dam, respectively. Each sector consists of
three sites; main channel (M) in addition to eastern (E) andwestern (W) banks (Fig. 1).
Analysis
Sediment samples were prepared using the decantation method(Folk, 1980), where grain size analysis was done by the drysieving technique (Folk, 1980). Samples containing more than
5% fine fraction (finer than 4Ø) were analyzed using the pip-ette method described by Krumbien and Pettijohn (1938),Griffiths (1951) and Carver (1971). Sediment textural classes
were deduced according to Folk (1980). The sedimentologicalparameters were derived according to Folk and Ward (1957).The grain size of the sediments is indicated according to the
Udden–Wentworth scale (Udden, 1914; Wentworth, 1922).Sediment modes of transportation were interpreted usingCharacteristic of truncation lines at inflection points of cumula-tive lines and C–M diagram according to Visher (1969),
Bartholdy et al. (2007), Opreanu et al. (2007), Mycielska-Dowgiao and Ludwikowska Kedzia (2011), and Passega(1964). One Way ANOVA statistical analysis was carried out
using Statisticaª program version 8 and correlation analysiswas carried out using SPSSª program version 20.
Results
Grain-size analysis
Grain-size distribution
Both weight-percentage frequency curves and cumulativeweight-percentage frequency curves have been constructed inorder to identify possible trends. Comparison of these curvesfor the sediments of the two seasons indicates that there were
clear trends of Lake Nasser sediments, the main channel sedi-ments consisted mainly from mud fraction with variableamount of sand (fine and very fine sand), whereas the bank
sediments have no clear trend just depending on topographical
features, which may lead to increase gravel to 100% (sites 2Wand 3E BFS). Sand fractions (fine and very fine sand) werewidely distributed at bank sites especially westwards reaching
94.40% at site 1W AFS and 79.10% at site 10E BFS. Clayfraction has a clear trend; increases southward; it reached upto 90.34 and 72.65% at sites 9M DDP and DFP, respectively.Silt fractions increase toward both banks and northward. It
reached to 57.60% at site 2E (DDP), while (DFP) it recorded52.65% at site 6M (Figs. 2 and 3; Tables 1 and 2).
The Main channel (M) sediment textural classes are mainly
silty clay southward DDP, while DFP was sandy mud.Sediments of the bank sites (E & W) were sandy mud andmuddy sand northward DDP, while southward they were silty
clay and clayey silt. DFP they were sandy mud and muddysand.
Results illustrate that depth controlled the distribution of
grain size. Mud increased with increasing depth while sandfractions decreased in the same trend. Mud fractions are corre-lated positively and significantly with depth (r= 0.48*,p= 0.05 (*: significant at 0.05%)), while sand fractions
are correlated negatively and significantly with depth(r = �0.48*, p = 0.05 (*: significant at 0.05%)), but some sitesdeviate from this pattern.
To find out whether the population variances are equal orthere are insignificant differences between the means of severalvariables, statistical tests must be carried out (Dean and Voss,
1999; Walpole et al., 2004; Srivastava et al., 2012). A one-wayANOVA was applied between the grain size fractions (gravel,sand, mud, and clay) and the studied periods (during drought
and flooding periods). Table 3 shows the calculated values.Results indicate that gravel fraction is insignificant with sea-sons (p = 0.52) it may be due to local topography factor.Sand and mud fractions are significant with seasons
(p = 0.0065, and 0.0117 for sand and mud, respectively),which indicate that the distribution of sand and mud fractionswere affected by flood season.
Grain-size parameters
The grain size parameters of Lake Nasser sediments were cal-culated from cumulative curves and given in Tables 4 and 5.
Table 1 Sediment fraction percent and textural classes of Lake Nasser sediment during the drought period.
Station Gravel V.C. Sand C. Sand M. Sand F. Sand V.F. Sand C. Silt M. Silt F. Silt V.F. Silt Gravel San Silt Clay Mud Sediment type
1M 0.00 0.00 0.00 0.00 0.00 0.00 13.93 3.35 6.03 2.80 0.00 0.0 26.11 73.89 100.00 Mud (Silty clay)
1E *** *** *** *** *** *** *** *** *** *** *** *** *** *** 0.00 ***
1W 0.00 0.00 0.00 0.00 23.09 31.20 26.56 3.55 1.64 2.23 0.00 54. 33.98 11.73 45.71 Muddy sand
2M 0.00 0.00 0.00 0.00 0.00 0.00 11.02 2.85 6.99 6.88 0.00 0.0 27.73 72.27 100.00 Mud (Silty clay)
2E 0.00 0.00 0.00 0.00 0.00 0.00 46.55 4.10 5.89 1.06 0.00 0.0 57.60 42.40 100.00 Mud (Silty clay)
2W 100.00 0.00 0.00 0.00 0.00 0.00 0.00 00.00 0.00 0.00 100.00 0.0 100.00 0.00 0.00 Gravel
3M 0.00 0.00 0.00 10.17 13.41 19.33 14.17 3.13 4.33 9.34 0.00 42. 30.97 26.13 57.09 Sandy mud
3E 95.71 0.00 0.00 0.00 0.00 0.00 ——— ——— ——— ——— 95.71 0.0 ——— ——— 3.29 Muddy gravel
3W 0.00 0.00 0.00 0.00 14.27 25.42 6.66 5.56 0.67 11.29 0.00 39. 24.17 36.13 60.31 Sandy mud
4M 16.59 0.00 0.00 0.00 0.00 19.91 15.34 3.72 3.29 1.42 16.59 19. 23.76 39.73 63.50 Gravelly sandy mud
4E *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
4W 30.78 0.00 0.00 0.00 8.74 18.08 6.71 9.28 0.38 3.68 30.78 26. 20.05 22.35 42.40 Sandy gravelly mud
5M *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
5E *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
5W *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
6M 0.00 0.00 0.00 0.00 0.00 0.00 5.91 1.57 0.47 4.01 0.00 0.0 11.96 88.04 100.00 Mud (Silty clay)
6E 0.00 0.00 0.00 0.00 0.00 0.00 7.65 2.19 1.81 39.33 0.00 0.0 50.97 49.03 100.00 Mud (Clayey silt)
6W 0.00 0.00 0.00 0.00 0.00 0.00 9.44 0.24 37.50 5.88 0.00 0.0 53.06 46.94 100.00 Mud (clayey silt)
7M 0.00 0.00 0.00 0.00 0.00 0.00 6.43 3.38 1.64 2.98 0.00 0.0 14.43 85.57 100.00 Mud (Silty clay)
7E 0.00 0.00 0.00 0.00 0.00 0.00 7.94 6.13 3.29 20.43 0.00 0.0 37.80 62.20 100.00 Mud (Silty clay)
7W 0.00 0.00 0.00 0.00 0.00 7.24 8.91 3.96 27.05 0.90 0.00 7.2 40.83 51.94 92.76 Sandy mud
8M 0.00 0.00 0.00 0.00 0.00 14.19 3.04 1.61 2.87 0.70 0.00 14. 8.21 77.60 85.81 Sandy mud
8E 0.00 0.00 0.00 0.00 0.00 0.00 4.53 1.73 8.04 5.99 0.00 0.0 20.29 79.71 100.00 Mud (Silty clay)
8W 0.00 0.00 0.00 0.00 0.00 9.63 3.94 1.48 5.97 11.40 0.00 9.6 22.80 67.57 90.37 Sandy mud
9M 0.00 0.00 0.00 0.00 0.00 0.00 3.41 1.76 1.34 3.15 0.00 0.0 9.66 90.34 100.00 Mud (Silty clay)
9E 0.00 0.00 0.00 0.00 0.00 0.00 12.80 12.14 1.54 7.87 0.00 0.0 34.34 65.66 100.00 Mud (Silty clay)
9W *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
10M 0.00 0.00 0.00 0.00 0.00 0.00 7.59 4.78 7.31 6.60 0.00 0.0 26.28 73.72 100.00 Mud (Silty clay)
10E 1.71 2.30 4.69 15.94 31.93 24.23 7.58 4.30 0.08 0.32 1.71 79. 12.29 6.91 19.20 Muddy gravelly sand
10W 47.00 12.73 11.93 8.51 9.12 7.01 ——— ——— ——— ——— 47.00 49. 0.00 65.66 3.70 Gravelly muddy sand
———: sample with mud fraction less than 5%; ****: Not collected sample; VC: very coarse; C: coarse; M: medium; F: fine; VF: very fi .
Effect
offloodingonsed
iments
ofLakeNasser
169
d
0
29
0
0
0
91
0
69
91
82
0
0
0
0
0
4
19
0
3
0
0
0
10
30
ne
Table 2 Sediment fraction percent and textural classes of Lake Nasser sediment during the flooding period.
Station Gravel V.C.
Sand
C.
Sand
M.
Sand
F.
Sand
V.F.
Sand
C. Silt M. Silt F. Silt V.F. Silt Clay Grave Sand Silt Clay Mud Sediment type
1M 0.00 0.00 0.00 0.00 0.00 0.00 8.54 10.85 9.43 2.54 68.64 0.00 0.00 31.36 68.64 100.00 Mud (Silty
clay)
1E *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
1W 2.07 1.33 10.88 44.35 25.92 11.93 ————— ————— ————— ————— ————— 2.07 94.40 ——— ——— 3.53 Gravelly
muddy sand
2M 0.00 0.00 0.00 0.00 0.00 13.45 8.42 18.08 11.04 9.15 39.86 0.00 13.45 46.69 39.86 86.55 Sandy mud
2E 0.00 0.00 0.00 19.05 20.70 20.51 20.81 3.80 3.06 0.84 11.23 0.00 60.25 28.52 11.23 39.75 Muddy sand
2W 0.00 0.00 0.00 23.51 37.43 20.72 1.63 3.48 1.54 2.48 9.21 0.00 81.66 9.13 9.21 18.34 Muddy sand
3M 0.00 0.00 0.00 0.00 27.85 42.94 7.98 6.37 4.09 2.26 8.51 0.00 70.79 20.70 8.51 29.21 Muddy sand
3E *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
3W 0.00 0.00 0.00 0.00 26.32 38.95 2.33 4.50 5.08 4.67 18.15 0.00 65.27 16.58 18.15 34.73 Muddy sand
4M 0.00 0.00 0.00 0.00 0.00 32.54 13.14 15.55 9.33 4.56 24.88 0.00 32.54 42.58 24.88 67.46 Sandy mud
4E *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
4W 0.00 0.00 0.00 0.00 0.00 22.67 4.24 18.61 8.66 10.90 34.93 0.00 22.67 42.40 34.93 77.33 Sandy mud
5M 0.00 0.00 0.00 0.00 13.55 22.61 12.67 12.24 9.15 5.24 24.54 0.00 36.16 39.30 24.54 63.84 Sandy mud
5E *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
5W *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
6M 0.00 0.00 0.00 0.00 0.00 0.00 7.19 17.88 18.78 8.81 47.35 0.00 0.00 52.65 47.35 100.00 Mud (Clayey
silt)
6E *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
6W *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
7M 0.00 0.00 0.00 0.00 0.00 34.55 10.76 8.61 7.34 8.10 30.64 0.00 34.55 34.81 30.64 65.45 Sandy mud
7E 0.00 0.00 0.00 0.00 25.06 29.15 14.71 1.74 1.45 1.88 26.02 0.00 54.21 19.77 26.02 45.79 Muddy sand
7W 0.00 0.00 0.00 0.00 10.41 27.15 16.50 15.79 10.82 5.54 13.78 0.00 37.56 48.66 13.78 62.44 Sandy mud
8M 0.00 11.43 12.85 8.51 4.96 3.71 12.63 9.96 8.99 19.77 51.35 0.00 7.19 41.46 51.35 92.81 Sandy mud
8E 0.00 0.00 0.00 0.00 12.11 48.54 11.66 10.83 4.63 2.37 9.86 0.00 60.65 29.49 9.86 39.35 Muddy sand
8W 0.00 6.42 5.84 3.52 2.62 2.99 7.44 4.22 3.63 1.21 62.11 0.00 21.39 16.50 62.11 78.61 Sandy mud
9M 0.00 0.00 0.00 0.00 0.00 0.00 11.41 4.10 0.58 11.26 72.65 0.00 0.00 27.35 72.65 100.00 Mud (Silty
clay)
9E 0.00 0.00 0.00 0.00 0.00 27.86 13.15 0.91 9.61 0.96 47.50 0.00 27.86 24.64 47.50 72.14 Sandy mud
9W *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
10M *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
10E *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
10W *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
—————: Sample with mud fraction less than 5%; ****: Not collected sample; VC: very coarse; C: coarse; M: medium; F: fine; VF: very ne.
170
H.I.
Farhat,S.G
.Salem
l
fi
Effect of flooding on sediments of Lake Nasser 171
The mean grain size is a parameter related to the overall grainsize, sorting or the uniformity of the grain-size distribution,Skewness is a measure of symmetrical distribution, i.e. the pro-
portion of coarse or fine fractions. A symmetrical curve withexcess fine material shows a positive value, whereas one withexcess coarse material shows a negative value; a zero value is
indicated by a symmetrical curve, while the kurtosis expressesthe peakedness of the grain-size distribution (Srivastava et al.,2012). During the drought period, the main size ranged
between gravel and clay (�1.30 to 8.22Ø), while during theflooding period it ranged between medium sand and very finesilt (1.98–7.6Ø). DDP sorting ranged between medium well
Table 3 One-way ANOVA between fractions (gravel, sand,
clay, and mud) and studied periods (during drought and
flooding periods).
Fraction One-way ANOVA
p value Outcome
Gravel 0.5224 Non-significant
Sand 0.0065 Significant
Clay 0.0076 Significant
Mud 0.0117 Significant
Table 4 Sedimentological parameters of Lake Nasser sediment dur
Station Mean size (Mz) (rI)Sorting
Value(Ø) Type Value(Ø) Type
1M 7.35 Very fine silt 1.25 Poorly sorted
1E ****** ****** ****** ******
1W 4.27 Coarse silt 1.61 Poorly sorted
2M 7.57 Very fine silt 1.06 Poorly sorted
2E 6.32 Fine silt 1.44 Poorly sorted
2W 5.03 Medium silt 2.38 Very poorly sorted
3M 5.70 Fine silt 2.12 Very poorly sorted
3E �1.30 Gravel 0.19 Very well sorted
3W 4.07 Coarse silt 3.76 Very poorly sorted
4M 3.50 Very fine sand 3.78 Very poorly sorted
4E ****** ****** ****** ******
4W 8.20 Clay 0.66 Medium well sorted
5M ****** ****** ****** ******
5E ****** ****** ****** ******
5W ****** ****** ****** ******
6M 7.80 Very fine silt 0.78 Moderately sorted
6E 7.20 Very fine silt 1.03 Poorly sorted
6W 8.20 Clay 0.63 Medium well sorted
7M 7.65 Very fine silt 0.96 Moderately sorted
7E 7.07 Very fine silt 1.48 Poorly sorted
7W 6.98 Fine silt 1.70 Poorly sorted
8M 7.90 Very fine silt 0.76 Moderately sorted
8E 7.45 Very fine silt 1.26 Poorly sorted
8W 8.22 Clay 0.49 Well sorted
9M 7.17 Very fine silt 1.30 Poorly sorted
9E 7.62 Very fine silt 1.00 Poorly sorted
9W ****** ****** ****** ******
10M 7.22 Very fine silt 1.30 Poorly sorted
10E 2.85 Fine sand 1.87 Poorly sorted
10W 0.37 Coarse sand 1.91 Poorly sorted
******: Not collected sample.
sorted and very poorly sorted (0.63–3.78Ø), where it was mod-erately sorted to very poorly sorted (0.98–2.18Ø) DFP. Theskewness was symmetrical to strongly fine-skewed and near
symmetrical to strongly fine-skewed DDP and DFP, respec-tively. Kurtosis varied between very platykurtic to extremelyleptokurtic during both periods.
Sediment mode of transportation
Visher (1969) related the modes of sediment transportation; by
traction, saltation and suspension; by distinguishing three dis-tinct sectors of the cumulative curve in the form of straightlines of different lengths and slopes. Lake Nasser sediments
DDP indicate a prominent truncation between traction andsaltation at a range of �1.1 and 5.00 ± 0.2Ø with percentageranged between 1.9% and 47.0% except at site 3 E that was�1.0Ø with percentage of 95.5% due to access of gravel frac-
tion. Truncation between saltation and suspension was morethan 4Ø which ranged between 4.0 and 8.00Ø with percentageranged between 6.0% and 91.0%. Suspension load ranged
between 4.5% and 90.5%. DFP results indicate a prominenttruncation between traction and saltation at a range of �1.0and 5.0 ± 0.2Ø with percentage ranged between 2.0% and
34.0%. Truncation between saltation and suspension wasmore than 8Ø with percentage ranged between 11.0% and
ing the drought period according to Folk and Ward (1957).
Skewness (SKI) Kurtosis (KG)
Value Type Value Type
�0.80 Strongly coarse-skewed 1.68 Very lepto-kurtic
****** ****** ****** ******
0.46 Strongly fine-skewed 1.41 Very lepto-kurtic
�0.79 Strongly coarse-skewed 2.53 Very lepto-kurtic
0.27 Fine-skewed 0.47 Very platy-kurtic
0.23 Fine-skewed 0.54 Very platy-kurtic
0.00 Near symmetrical 0.50 Very platy-kurtic
�0.07 Symmetrical 1.23 Very lepto-kurtic
�0.28 Coarse-skewed 0.85 Platy-kurtic
�0.03 Near symmetrical 0.47 Very platy-kurtic
****** ****** ****** ******
�0.39 Strongly coarse-skewed 6.07 Extremely lepto-kurtic
****** ****** ****** ******
****** ****** ****** ******
****** ****** ****** ******
�0.69 Strongly coarse-skewed 1.91 Very lepto-kurtic
�0.16 Coarse-skewed 0.90 Meso-kurtic
�0.43 Strongly coarse-skewed 5.74 Extremely lepto-kurtic
�0.75 Strongly coarse-skewed 1.79 Very lepto-kurtic
�0.85 Strongly coarse-skewed 0.95 Meso-kurtic
�0.87 Strongly coarse-skewed 7.62 Extremely lepto-kurtic
�0.75 Strongly coarse-skewed 5.08 Extremely lepto-kurtic
�0.81 Strongly coarse-skewed 1.96 Very lepto-kurtic
�0.33 Strongly coarse-skewed 5.43 Extremely lepto-kurtic
�0.81 Strongly coarse-skewed 0.67 Platy-kurtic
�0.79 Strongly coarse-skewed 4.16 Extremely lepto-kurtic
****** ****** ****** ******
�0.82 Strongly coarse-skewed 0.67 Platy-kurtic
0.23 Fine-skewed 2.12 Very lepto-kurtic
0.77 Strongly fine-skewed 0.69 Platy-kurtic
Table 5 Sedimentological parameters of Lake Nasser bottom sediment during the flooding period according to Folk and Ward
(1957).
Station Mean size (Mz) (rI)Sorting Skewness (SKI) Kurtosis (KG)
Value(Ø) Type Value(Ø) Type Value Type Value Type
1M 7.60 Very fine silt 0.98 Moderately sorted �0.69 Strongly coarse-skewed 1.59 Very lepto-kurtic
1E ****** ****** ****** ****** ****** ****** ****** ******
1W 1.98 Medium sand 1.00 Poorly sorted 0.09 Near symmetrical 1.12 Lepto-kurtic
2M 6.50 Very fine silt 1.66 Poorly sorted �0.40 Strongly coarse-skewed 0.64 Very platy-kurtic
2E 3.72 Very fine sand 1.90 Poorly sorted 0.31 Strongly fine-skewed 1.13 Lepto-kurtic
2W 3.23 Very fine sand 1.78 Poorly sorted 0.59 Strongly fine-skewed 1.65 Very lepto-kurtic
3M 4.05 Coarse silt 1.56 Poorly sorted 0.62 Strongly fine-skewed 1.43 Lepto-kurtic
3E ****** ****** ****** ****** ****** ****** ****** ******
3W 4.83 Coarse silt 2.11 Very poorly sorted 0.70 Strongly fine-skewed 0.64 Very lepto-kurtic
4M 5.70 Medium silt 1.75 Poorly sorted 0.34 Strongly fine-skewed 0.46 Very lepto-kurtic
4E ****** ****** ****** ****** ****** ****** ****** ******
4W 6.13 Fine silt 1.75 Poorly sorted �0.18 Coarse-skewed 0.53 Very lepto-kurtic
5M 5.42 Medium silt 2.07 Very poorly sorted 0.17 Fine-skewed 0.51 Very lepto-kurtic
5E ****** ****** ****** ****** ****** ****** ****** ******
5W ****** ****** ****** ****** ****** ****** ****** ******
6M 7.17 Very fine silt 1.18 Poorly sorted �0.61 Strongly coarse-skewed 0.67 Platy-kurtic
6E ****** ****** ****** ****** ****** ****** ****** ******
6W ****** ****** ****** ****** ****** ****** ****** ******
7M 5.82 Medium silt 1.77 Poorly sorted 0.21 Fine-skewed 0.46 Very platy-kurtic
7E 4.93 Coarse silt 2.15 Very poorly sorted 0.63 Strongly fine-skewed 0.46 Very platy-kurtic
7W 5.20 Medium silt 1.89 Poorly sorted 0.32 Strongly fine-skewed 0.79 Platy-kurtic
8M 7.17 Very fine silt 1.18 Poorly sorted �0.61 Strongly coarse-skewed 0.67 Platy-kurtic
8E 4.33 Coarse silt 1.56 Poorly sorted 0.58 Strongly fine-skewed 1.10 Meso-kurtic
8W 7.45 Very fine silt 1.12 Poorly sorted �0.71 Strongly coarse-skewed 2.39 Very lepto-kurtic
9M 7.60 Very fine silt 1.03 Poorly sorted �0.80 Strongly coarse-skewed 3.74 Extremely lepto-kurtic
9E 6.30 Fine silt 1.78 Poorly sorted �0.34 Strongly coarse-skewed 0.46 Very platy-kurtic
9W ****** ****** ****** ****** ****** ****** ****** ******
10M ****** ****** ****** ****** ****** ****** ****** ******
10E ****** ****** ****** ****** ****** ****** ****** ******
10W ****** ****** ****** ****** ****** ****** ****** ******
******: Not collected sample.
172 H.I. Farhat, S.G. Salem
94.5%. Suspension load ranged between 3.5% and 84.0%
(Table 6).
C–M patterns
The results obtained from grain-size analyses are presented in
a Passega C–M diagram (Passega, 1964; Passega andByramjee, 1969; Mycielska-Dowgiao and Ludwikowska-Kedzia, 2011), where the values of ‘‘C’’ the first percentile
are plotted against the ‘‘M’’ median grain diameter.C–M application is used widely to interpret different
depositional environments. (Ludwikowska-Kedzia, 2000;
Szmanda, 2002; Ostrowska et al., 2003; Bartholdy et al.,2007; Opreanu et al., 2007; Mycielska-Dowgiao andLudwikowska-Kedzia, 2011; Farhat, 2010, 2013; Srivastava
et al., 2012; Pisarska-Jamro _zy, 2013; Ramamohanarao et al.,2003). There was a clear trend of the sediment of LakeNasser during the drought period showing that most of sedi-ments fall in pelagic suspension (T) (especially main channel
M) in which sediments are settled from suspension in stagnantwater. It may be due to the great depth as wave and currentactivity decrease toward deeper parts of the lake. According
to Fig 4, sites 2W and 3W fall in field 3 (i.e. rolling), 4Mand 10E fall in field 2 (i.e. rolling), 3M and 10W fall in field
1 (i.e. rolling), 1W falls in uniform suspension and 3E falls
in overbank-pool facies suspension. During flooding periodthere was no clear trend for the studied sediments, most ofthe main channel (M) samples fall in pelagic suspension (T),1W falls in field 2 (i.e. rolling), 2E and 2W fall in graded sus-
pension (transported mainly by siltation), 4M, 7M, and 7Wfall in overbank facies suspension, 5M falls in suspension,and 3W, 3M, 7E and 8E fall in uniform suspension.
Discussion
The field description of the bottom sediments under concern
indicates that the darkest color of sediment was observed nearAswan; this may be due to relatively old sediments and theanoxic conditions during stagnation period before flood sea-
son; while light color was observed southward; especially dur-ing the flooding period; this may be due to deposition of freshsediment southward. The sediments of Lake Nasser are hetero-
geneous. The main channel sediments are mainly silty clay andclayey silt, while the eastern and western sides include moresand and depend on the local topography. Deposition of sandfrom the adjacent sand dunes scattered along the western bank
of Lake Nasser takes place as aeolian deposits. The highestpercentage of clay was recorded in the main channel of the
Table 6 Characteristics of truncation lines of Lake Nasser bottom sediment during 2013.
Station Spring 2013 Autumn 2013
Traction/Saltation Saltation/Suspension Suspension Traction/Saltation Saltation/Suspension Suspension
ø Wt% ø Wt% Wt% ø Wt% ø Wt% Wt%
1M 5.00 14.00 7.50 72.00 14.00 4.00 9.00 8.00 36.50 54.50
1E *** *** *** *** *** *** *** *** *** ***
1W 3.00 23.00 4.90 57.00 20.00 �1.00 2.00 8.00 94.50 3.50
2M 5.00 12.00 8.00 15.00 73.00 4.00 13.00 8.00 47.00 40.00
2E 5.00 47.00 8.00 10.00 43.00 2.00 19.00 8.00 70.00 11.00
2W 2.00 11.00 8.00 63.00 26.00 2.00 23.00 8.00 67.50 9.50
3M 4.00 39.50 8.00 24.50 36.00 3.00 27.00 8.00 64.50 8.50
3E �1.00 95.50 4.00 0.00 4.50 *** *** *** *** ***
3W 1.00 16.00 8.00 44.00 40.00 3.00 26.00 8.00 55.00 19.00
4M �1.00 30.50 8.00 47.00 22.50 4.00 32.00 8.00 43.00 25.00
4E *** *** *** *** *** *** *** *** *** ***
4W 5.00 6.00 8.00 6.00 88.00 4.00 23.00 8.00 42.00 35.00
5M *** *** *** *** *** 3.00 14.00 8.00 61.00 25.00
5E *** *** *** *** *** *** *** *** *** ***
5W *** *** *** *** *** *** *** *** *** ***
6M 5.00 8.00 8.00 42.00 50.00 5.00 7.00 8.00 46.00 47.00
6E 5.00 9.00 8.00 45.00 46.00 *** *** *** *** ***
6W 5.00 6.50 8.00 7.50 86.00 *** *** *** *** ***
7M 5.00 8.00 8.00 30.00 62.00 4.00 34.00 8.00 35.00 31.00
7E 4.00 7.00 8.00 42.00 51.00 3.00 25.00 8.00 49.00 26.00
7W 4.00 14.00 8.00 8.00 78.00 3.00 10.00 8.00 76.00 14.00
8M 5.00 4.50 8.00 15.50 80.00 5.00 7.00 8.00 14.50 78.50
8E 4.00 9.50 8.00 22.50 68.00 3.00 12.00 8.00 78.00 10.00
8W 5.00 3.50 8.00 6.00 90.50 4.00 5.00 8.00 11.00 84.00
9M 5.00 15.00 8.00 29.00 56.00 5.00 11.00 8.00 15.00 74.00
9E 5.00 7.50 8.00 17.50 75.00 4.00 27.00 8.00 29.00 44.00
9W *** *** *** *** *** *** *** *** *** ***
10M 5.00 13.00 8.00 22.00 65.00 *** *** *** *** ***
10E �1.00 1.90 8.00 91.10 7.00 *** *** *** *** ***
10W �1.00 46.00 4.00 30.00 24.00 *** *** *** *** ***
***: Not collected sample.
Effect of flooding on sediments of Lake Nasser 173
southern sites at Tushka, Abu Simbel and Adindan (Entz and
Latif, 1974; Philip et al., 1977; Scott et al., 1978; El Dardir,1984, 1987, 1994; Fishar, 1995; El-Manadely et al., 2002;Iskaros and El Dardir, 2010).
In agreement with Ligeza and Smal (2002) who studied thesediment of the Dobczyce reservoir, and Teeter et al. (2001)and Wetzel (2001) who studied Myslenice Basin, it is clear that
depth is controlling the distribution of grain size. Finesincreased with increasing of depth while sand fractionsdecreased. This indicates less current effects on deeper sedi-ments. Re-suspension of fine particles from a shallow area
and its re-deposition in a deeper part of the water body affectsignificantly the texture of sediment in the shallow part of thereservoir, but some sites deviate from this pattern due to geo-
morphic features of the reservoir. Concentration of suspendedsediments decreases northward. The lake sediments are con-sisting of sand, silt and clay, with non-uniform composition
pattern. The variation in the sediment composition is due toboth time and topographical features characterizing depositedsediment particles. After drought periods, high floods decrease
the dead storage zone of Lake Nasser by filling it with re-de-posited sediments coming from southern zones (El-Manadleyet al., 2002).
The decreasing of fines and increasing of sand fraction
DFP; than DDP; indicate that the percent of sands increasedas the flood season started, it may be a result of washing ofbottom sediments by high energy water current caused by
the flood which carries fine as suspended material leaving sandfractions. It agrees with El-Manadely et al. (2002) who statedthat proportion of sand tended to increase as the flood season
progressed.Grain-size distributions are widely used to study various
sedimentary facies and environments of deposits. Sand frac-tion part of the cumulative curves is considered to be a normal
distribution, admixtures of coarser and finer grains occur,which do not form normal distributions (Tanner, 1964).Nevertheless, their presence or absence is important for the
interpretation of the sedimentary environment (Mycielska-Dowgiao and Ludwikowska-Kedzia, 2011).
Most of the cumulative curves of the sediments of the present
study have clear different sectors with clear straight line andinflection points. During the drought period, it can be deducedfrom the curves that suspensionwas themost prominent formof
transport, followed by siltation, while truncation was of minorimportance. It means that curves most closely resemble thesecond group of cumulative curves in which sediments are
Figure 4 C–M Pattern diagrams showing mode of transportation of Lake Nasser sediments. (A) During the drought period, (B) During
the flooding period.
174 H.I. Farhat, S.G. Salem
transported by a medium of considerable density. During the
flooding period siltation was most predominant mode of trans-portation, followed by suspension and truncation was of lessimportance, which means that curves most closely resemble
the third group of cumulative curves, (transitional group includ-ing mixed sediments formed by short-lived depositional pro-cesses, deposits resulting from various overlapping processes
and depositional environments) (Mycielska-Dowgiao andLudwikowska-Kedzia, 2011; Srivastava et al., 2012;Wachecka-Kotkowska and Ludwikowska-Kedzia, 2013).
The mode of transportation of Lake Nasser sediments dur-
ing the drought period was pelagic suspension in which sedi-ments were settled from suspension in stagnant water, whilerolling, overbank facies suspension and uniform suspension
were less important. During the flooding period there was noclear trend for the studied sediments, most of the main channelsamples fall in pelagic suspension, while rolling, graded sus-
pension, overbank facies suspension, suspension and uniformsuspension were widely distributed. Passega C–M diagram ishelpful for the study of fluvial deposits, even though it waselaborated initially for the marine environment. It has been
useful for the study of fluvial and coastal deposits, becauseboth formed from different lithofacies, by which the diagramis useful to explain the depositional sub-environments.
Different transport and depositional histories can thus be
distinguished (Ludwikowska-Kedzia, 2000; Mycielska-
Dowgiao and Ludwikowska-Kedzia, 2011; Szmanda, 2002).
Conclusion
The present study results conclude that Lake Nasser sedimentsare heterogeneous. The main channel sediments are mainlysilty clay and clayey silt, while the eastern and western sites
include more sand which depends on the local topography.The highest percentage of clay was recorded in the main chan-nel southward. Depth controlled distribution of grain size
(deeper is finer) with some sites deviates from this pattern.Sand fractions increased as the flood season started.
Cumulative curves indicate that during the drought periodsuspension was the most prominent form of transportation,
followed by siltation, while truncation was of minor impor-tance, which means that sediments were transported by a med-ium of considerable density. During the flooding period
siltation was most predominant mode of transportation, fol-lowed by suspension, while truncation was less important,which means that this environment has a high energy and vari-
ety of depositional environments.C–M pattern diagram indicates that sediments of Lake
Nasser during the drought period were pelagic suspension in
Effect of flooding on sediments of Lake Nasser 175
which sediments were settled from suspension in stagnantwater, while rolling, overbank facies suspension and uniformsuspension were less important. During the flooding period
there was no clear trend, most of the main channel samples fallin pelagic suspension, while rolling, graded suspension, over-bank facies suspension, suspension and uniform suspension
were widely distributed for banks.Further studies are recommended, just like roundness and
surface morphology of quartz grains of sand and silt, the
petrographical composition of the light minerals, and com-position of heavy-mineral assemblages for determining thesource material of Lake Nasser sediments, as well as theenvironment and dynamics of their transport and deposition.
Acknowledgements
This work was supported by the research plan of theEnvironment of Freshwater and Lakes Division, NationalInstitute of Oceanography and Fisheries, Egypt in order to
identify and evaluate the environmental and fisheries statusof Lake Nasser during 2013.
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