Post-Aswan Dam sedimentation

rate of lagoons of the Nile Delta,

Egypt

Jiawei Gu1 , Zhongyuan Chen1, and Alaa Salem2

1 State Key Laboratory of Estuarine and Coastal Research of ECNU, China2 Geology Department, Kafrelsheikh University, 33516 Kafrelsheikh, Egypt

On-going Project

This joint work aims to trace the sedimentation

rate and examine the concentration and transfer

processes of heavy metals in both estuaries

A comparative study on spatial and temporal

distribution of heavy metals in the Nile and

Yangtze coastal wetlands – the special reference

to ecological safety

Location

Map

Mediterranean Sea

Cairo

N i l e D e l t a

Remarks from Earlier Research

Lagoons of the Nile Delta have experienced more

pollution after the construction of Aswan high dam in

1964 as evidenced from its heavy metals concentration

and high TOM.

Sedimentation rate from low resolution coring ranges

from 0.20～0.56 cm/yr by 210Pb , 137Cs.

The upper 10-15 cm sediment was deposited after the

construction of Aswan High Dam in 1964.

Pb, Sr, Mn, Zn, and Cd are the main pollution metals.

• To examine the sedimentation rates in the

Nile Delta lagoons, particularly since

completion of the Aswan High Dam in 1964

based on high-resolution coring (1cm interval)

• To reconstruct the pollution history and

analyze the controlling mechanism

Objectives

• How does the post-dam depositional process act

in the Nile Delta ?

• What are the heavy metals distribution and

dispersal pattern in the lagoons of the Nile delta ?

Research Questions

Amounts of sediments transported into the Nile before and after Aswan

Damming (Data recorded from gauge station at Rosetta Promontory)

0

500

1000

1500

2000

2500

3000p

pm

ينايرفبراير

سمار

ابريل

مايويونيه

يوليوسأغسط

سبتمبر

أكتوبر

نوفمبر

ديسمبر

قبل السد العالى After DamBefore Damبعد السد العالى

Jan.Dec.

Study area

East Asian

Monsoon RegionStudy

Area

Edku

Burullus

Manzala

The Nile Delta

Materials and Methods

Heavy metal

analysis for six

cores using the ICP

Three sediment

cores were analyzed

for Pb210 and Cs137

using a high-purity

germanium well-type

detector

Granulometric

analysis was done

to determine the

proportions of

sand, silt, and clay

Sedimentation rate on the Nile Delta

CIC (Constant Initial Concentration) and the CRS (Constant

Rate of Supply) model were commonly used to calculate

sedimentation rates using 210Pb (Appleby and Oldfield 1983).

Sediment lithology of the three cores

Core M-1 coarser sediment with some

shell fragments (0–10 cm) and the finer

sediment with a few shell fragments

(10–25 cm)

Core B-4 exhibits remarkable

variations in sediment composition in

which four sediment sections could be

identified

Core E-1 shows more homogeneous

sediment composition

Depth distribution of ex210Pb

(CIC model) and 137Cs in the

three short sediment cores

~10 cm thick sediment deposited

after the Aswan damming in 1964

This low sedimentation rate (0.22-

0.27) is a consequence of dramatic

reduction in sediment load as a

result of damming

The 137Cs spikes at the core depth of

9.5 cm of B-4 and of 4.5 cm of E-1

helped identify the sedimentation

rates of 0.22 cm a-1

Exponential decline in ex 210Pb in

the upper section of M-1 and E-1 is

noticed showing a sedimentation

rate of about 0.27 cm a-1

Sedimentation rates revealed by the CRS model and

area loss of three lagoons during 1950–2010

The pre-dam sedimentation rates of this study in Manzala were relatively high,

around 0.5 cm a-1, but lower in Burullus and Edku at around 0.1–0.2 cm a-1,

compared with the results from previous studies of around 0.2–0.8 cm a-1

The sedimentation rates in Manzala dropped to 0.1–0.2 cm a-1 after the

completion of Aswan High Dam in 1964, and persisted for about two decades while

Burullus and Edku showed a slightly increasing trend

Heavy metals distribution of the Nile Delta

Upward increasing concentrations (Normalized) of most

heavy metals correspond well with the time of damming

(~10cm ) Ensuing large-scale industrialization

Spatial distribution of

heavy metals in Manzala,

Burullus, Edku

M-2>E-1>E-2>M-3>M-1>B-4

Controlling factors (in order

of importance):

• Wastewater type

(industrial>agriculture/sewage)

• Distance to the drain outlet

• Dispersal pattern

( prevailing wind and currents)

• Sediment type

(finer>coarse)

Contamination

Factors of six cores

(CF=surficial

/background value)

Most enriched metals:

Pb, Sr, Mn, Cu, Zn, Cr

Human activities and pollution process of heavy metals between the Yangtze Delta and Nile Delta

Concluded Remarks

This high-resolution radiometric study using short sediment cores

has essentially revealed the post-Aswan dam sedimentation of the Nile

lagoons.

There have been lower sedimentation rates ranging from 0.22 to 0.27 cm

a-1 as illustrated by 210Pb (CIC model). The results highlight the general

situation of post-dam sedimentation in the Nile lagoons due to the

impoundment of sediment in the reservoir since the 1960s.

However, using the CRS model, we have demonstrated a decreasing

trend of sedimentation rate during 1960–1980s, but increasing trend

since the late 1980s.

The post-dam sedimentation rates of the present study provide insights

into future, better coastal management.

Thanks for your attention!