Investigation of Subsurface Archaeological Features Using Ground Penetrating1

8/13/2019 Investigation of Subsurface Archaeological Features Using Ground Penetrating1

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Investigation of The subsurface archaeological features

using Ground Penetrating Radar (GPR) in ancient UR-city

(South west Nasiriya /Iraq)

BY

MAHMOUD A.H. ALKAFAJI

B. Sc. 2000

Supervised by

Ass. Prof Dr. Jassim M. Thabit Prof Ahmed S. Albana

2011 A.D.

Ministry of Higher Education

and Scientific Research

University of Baghdad

College of Science

Department of Geology


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N

SE

W

The study area

The study area lies in south of Nasiriya city within Thi-Qar province south

of Iraq, the study is made over the ancient city of Ur.The city of Ur is one of the most

important archaeological cities in the world, Ursbuildings were characterized by itsunique

architectural features, and had seen a tremendous advancement in the beauty of arts,

literature, invention of writing, metal smith, city planning, trade, laws, and imputationsystems. Most buildings were built with clay bricks and thebinding materials used was

a natural (tar), which participated in preserving this site pretty well. Itsaesthetic properties

are still intact. Ur was represent the capital of the Sumerians in the third dynasty of Ur

(2113-2006 B.C) . Its lactation near the sea made it a center of commerce and trade routes.

Ur considered one of the oldest cities in the world and the largest city boasting about

65,000 inhabitants within its walls.


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The major objective of the research is to develop scientific studies in the field of archaeology in

Iraq by using the modern explorations techniques such as GPR technique. There is a large gap

in archeological services in Nasiriyah governorate, where the exploratory visits and

observations of field is the only way to determine of archeological sites.

There is a large expansion for the archeological sites in the Nasiriya governorate, and most of

these sites are unknown dimensions and are located in an urban. This causes made the work

halted in the some of service projects.

Therefore, it is very important and dire needs to investigate these

sites, especially the use of modern methods of exploration

(Nasiriya Museum department). Used of GPR technique met with

great acceptance from the Nasiriyah Museum department.

The study area lies in southwest of

Nasiriya city within Thi-Qar governorate

at the southern part of Iraq (figure 1-1),

about 380 Km to south east of Baghdad

, 200 km north of Al-Basra (Arabian Gulf),

6 km to the east of BaghdadBasrahigh - way

Location:N: 30 .9635

E: 46. 1072250 m


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Most geophysical methods used in the studying of archaeology areprincipally based on the detection of variations of magnetic and electricalproperties of underground soil, and identify and separate between artifacts and

the natural soil variations. Ground penetrating radar is a near-surfacegeophysical technique that allows investigators to discover and map (depthand dimensions) buried features. It is used electromagnetic waves (energy) todetermine underground features due to chemical or physical changes in theunderground soil.

The GPR technique is a non-destructive method of archaeologicalinvestigation, and is a valuable technique to the modern archaeological project.Excavation is often expensive and sometimes controversial. GPR can offer a

suitable and accurate data regarding site stratigraphy, and the location anddepths of covered features.

Ground-Penetrating Radar (GPR) Method

Antenna

unit

shielded

type

Control

unit

Display

unit

Power supply

Battery, 12

V.DC.


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Detailssurvey

Data processing

&

Interpretation

Evaluating of

GPR operating

Setting

Evaluatingtheexpected noise

Conductivity &

Permittivity of

the target & soil

Guess the

geometry of the

target

Guess the depth

of the target

Executive the profiles

survey in studied area

Executive the tests of the best

operating parameters setting

of GPR & anomaly form test

Fieldworks

The exploratoryfield visits

Design field survey Plan

Field

observations

Topographic &

nature of the site

Located

the site


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The summery of the exploratory field visit:

1) The characteristics of the site and fieldwork plane

A) The area represented a site of ancient city including many exposed buildings , walls and civilian tools used for housing or temples and tombs .

B) The natural of architectural of the building on the site have approximate

same architectural design .

C) The natural of geometry of the exposed features in the site, most of these features represented remains of buildings walls. The width of these walls

is between 1-2 m, and the depth is between 1-10m from the earth surface.

The walls have regular shapes such as rectangles.

D) The natural of materials in the site, the walls made of backed clay from the

host materials represented by clay and silt. This fact clear that the

subsurface features and the host materials have different in the

electrical properties of the materials (dielectric constant, and the electrical

conductivity) . The binders of the the backed clay bricks materials is asphalt,

and this is proof of the existence of high percentage of moisture which found

already in the archaeological features .

E) The natural of hydrological of the site, because of the site is far from any

surface water source the natural of hydrological not present, also the ground

water level found to be extending from (40-50) meter below ground surface .

The rains in winter are factor which affected on the site.

Earth surface leve

Sediments High= 2 m

1.5 m

width

Archaeological wall

Host materials

Asphalt in different places

These remains of clay sun-

baked, which found on surfaceare good evident to investigate

under this area.


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The studied area extended

about 250 mfrom Al-Zaqura

The Fieldwork plane :

The fieldwork plan included the flowing below

1- Selection of the study area . The dimensions and the size of studied area

were selected by the researcher and by cooperation with the Nassriya

Museum department.

2- Leveling works had been done to evaluate the topography of the studiedarea. The level varied between 0-0.25 cm, and about 12 m above sea level

3- Design field survey has been prepared based on the following data

Registered the marks

N15 m profile

length

P 14 P 15 P 16

1 m 1 m

Direction of profiles30 m

15 m

P 1 P 31

N


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GPR Data Acquisition

The final stage of the fieldwork survey represents raw data acquisition. One antenna used in this study; 2

MHz, the maximum penetration depth is between 5-15 m. This antenna was the only available in order

to achieve the survey.One of the research objectives is to study the capability of the GPR to detect the underground

archeological features. The capability of GPR depended on many factors such as antenna frequency,operating setting parameters, soil characteristics...etc. Therefore, the fieldwork measurements in this

study divided into two stages. The first stage included two test. The first test included nine profiles which

applied in the studied area to chose the best operating parameters setting of the GPR which it more

suitable and related to natural of studied area soil. The second test included four profiles applied in

exposed area extended about 250 m from the studied area in order to estimate the anomaly forms in the

site in general and specific at the study area. The second stage included thirty one profile applied at the

studied area.


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Data acquisition of first stage:Profiles of the operating parameterssetting tests

Velocity = 150 m / ns



Sample frequency = 3475.47MHz



Point interval = 0.10 m




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Data acquisition of first stage:Profiles of the GPR response for exposed archaeological walls

SE NW

The profile SA 1 is trident NW-SE vertically on

the wall strike

NWSE

The width of the

wall on the earth

surface is 1 m

0 m4 m

The profile SA2 is trident SW-NE

parallel to the wall strike

NE

SW

NE SW


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Data acquisition of second stage: Thirty one profiles are tending southnorth applied in the studied area. Appendix (I)

shows the final processing profiles from 1 to 31.

Profile (18) is shown here as sample of the raw data before applying any type of processing

producers . The experimental results of the first group were the best guide to get the survey

done smoothly and without confusion. Below are the settings of GPR used:

Antenna: 250 MHzTime windows : 189.1 ns

velocity : 90 m/ns

point interval :0.030 m

Sampling frequency :2548.68 MHz

Antenna separation : 0.31 m

Number of Sample :512


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Processing and Interpretation of field data

Raw Data

Time zero adjustment filtersAmplitude Correction filters

(The timegain filter)

DC Removal filters

Band-pass filters Back ground Removal filter


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Interpretation the profilesof operating parameterssetting











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Interpretation the profilesof exposed anomalies form

Exposed wall

SE NW

Direction of the survey

The depth of investigation of radar signals

The upper

part of the

expected wall

The upper part

of the exposed wall

SWNE

Direction of the survey

Exposed wall

Expected wall

12

3


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E

E

The upper surface of the wall is at

depth of 1.25 mThe upper surface of the Arc

is at depth of 3.25 m

The width of the arc base is 1.75 m

The width of grave base is 1.40 m

Wall

W


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Interpretation of the profilesS

This arc

perhaps

represent soil

hill

N

The upper part

of the Expected wall

Deformed

anomaly

N

Expe

cted

wall

(V)

trenc

h

Or

Cupshap

e

S

The upper part of

the wall

Depth of investigation of radar signals

Note: *Horizontal dotted line defines the depth of investigation of the radar signals of all the

profiles below

*Vertical solid lines defined the expected wall borders in all the profiles below

*The upper part of the Expected wall is extended between (1.25-1.5)m

S N

Expected

wall

Expected

wall

* Wall borders* Depth of

investigation of radar

signals

The upper part*

of the Expected wall


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Data Graphic Representation

C.I = 20 ns, Depth = 1.5 m Profiles spacing = 1 meter

N

P1 P31

Direction of

the surveys

30 m

15 m


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Profile

31

Survey

Direction

Ground surface

Profile

1

N

1.5 m depth

The almost subsurface features in the final graphic

representation shows that these shapes could be a

walls used for housings or temples or for any civil

buildings, where almost exposed buildings aroundAl-Zagurat were used for such purposes. These

results could be helpful to guide Iraqi Archaeologists in

future excavations to understand and the new secret of

this hosing area.

Investigation of Subsurface Archaeological Features Using Ground Penetrating1

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