a map showing the evolution of the seabed along the eastern coast of Tunisia, including the Kerknah and Djerba islands, between 1886 and 2022 Tools and software used : • Bathymetric survey maps 1886 • ArcGIS PRO (Data processing software) • GEBCO (Current Bathymetric data) • Microsoft Excel work process : The first step was to digitize the map. This involves scanning the physical map and converting it into a digital format that can be viewed and edited on a computer. • Once the map was digitized, it was imported into the ArcGIS software for further processing. • ArcGIS is a powerful geographic information system (GIS) software that allows users to analyse, manage, and display spatial data. It can be used to create maps, perform spatial analysis, and manage geographic data. • The digitized map was then overlaid with bathymetry data from GEBCO, a web site that provides global bathymetry data. This allows the examination of changes in the seabed over time and create a map showing the evolution of the seabed between 1886 and 2022. • The results were then presented in a Microsoft Excel spreadsheet, allowing for easy visualization and analysis of the data.

1. Mapping of the Kerkennah seabed between 1886 and 2022:
By Mahdi Madi
Objective:
create a map showing the evolution of the seabed
along the eastern coast of Tunisia, including the
Kerknah and Djerba islands, between 1886 and 2022.
Tools and software:
• Bathymetric survey maps 1886
• ArcGIS PRO (Data processing software)
• GEBCO (Current Bathymetric data)
• Microsoft Excel
• The first step was to digitize the map. This involves scanning the physical map and converting it into a digital
format that can be viewed and edited on a computer.
• Once the map was digitized, it was imported into the ArcGIS software for further processing.
• ArcGIS is a powerful geographic information system (GIS) software that allows users to analyse, manage, and
display spatial data. It can be used to create maps, perform spatial analysis, and manage geographic data.
• The digitized map was then overlaid with bathymetry data from GEBCO, a web site that provides global
bathymetry data. This allows the examination of changes in the seabed over time and create a map showing
the evolution of the seabed between 1886 and 2022.
• The results were then presented in a Microsoft Excel spreadsheet, allowing for easy visualization and analysis
of the data.

2. In ArcGIS Pro, digitizing is the process of creating vector data by tracing over existing features or drawing them
manually on a map. Digitizing is a common task in GIS, as it allows users to create accurate, detailed maps and spatial
data that can be used for a wide range of applications.
To digitize features in ArcGIS Pro, you will need to have a map open and be in an editable layer. You can then use the
"Edit" tab in the ribbon to access the digitizing tools. Some common digitizing tools include:
• "Add Point": Allows you to create a new point feature by clicking on the map.
• "Add Line": Allows you to create a new line feature by clicking on the map to set vertices.
• "Add Polygon": Allows you to create a new polygon feature by clicking on the map to set vertices.
You can also use the "Sketch" tool to draw freehand lines or polygons on the map.
Once you have created a new feature, you can use the "Edit" tab to modify it by adding, deleting, or moving vertices.
You can also use the "Attribute Table" to add or edit the attributes of the feature.
Digitizing can be a time-consuming process, but it is an important skill to have in GIS as it allows you to create
accurate and detailed maps and spatial data.
Digitizing:
study area 4235 - 1

3. 1866 Radial-Basis-Function:
In ArcGIS Pro, a radial basis function (RBF) is a
mathematical function that can be used to
interpolate scattered data points. RBF
interpolation is a method of estimating the value
of a function at a given point based on the values
of the function at nearby points.
RBF interpolation can be useful in many
applications, including creating continuous
surfaces from discrete data points, smoothing
noisy data, and estimating missing data values.
To use RBF interpolation in ArcGIS Pro, you will
need to have the Spatial Analyst extension
installed. With the Spatial Analyst extension, you
can use the "RBF Interpolation" tool to create an
RBF surface from a set of input data points. The
tool allows you to specify the type of RBF
function to use, as well as the search radius and
other parameters that control the interpolation
process.
Once the RBF surface has been created, you can
use it to perform spatial analysis, create maps,
and perform other tasks in ArcGIS Pro.
Reversing the depth data (post radial-basis function)
(The data need to be reversed to negative values to
effectively measure erosion and sedimentation values)
Raster functions are applied to a raster dataset or map
service in a similar way to how a formula is applied to
a cell in a spreadsheet. They take one or more input
rasters and apply a set of operations to them, producing
an output raster as a result.

4. 2022 GEBCO data:
GEBCO (the General Bathymetric
Chart of the Oceans) is a global
bathymetric chart that provides a
comprehensive and publicly available
dataset of the Earth's oceans. GEBCO
is a collaborative effort between the
International Hydrographic
Organization (IHO) and the
Intergovernmental Oceanographic
Commission (IOC) of the United
Nations Educational, Scientific, and
Cultural Organization (UNESCO).
The GEBCO dataset is created using a
combination of data sources,
including ship-based soundings,
satellite altimetry, and digital
elevation models. The data is then
compiled and quality-controlled to
create a consistent and accurate
representation of the Earth's ocean
floor.
The GEBCO dataset is available for
free download from the GEBCO
website and is widely used by ocean
scientists, marine engineers, and
others working in the field of
oceanography. It is also used in the
creation of nautical charts and other
products that help people navigate
the oceans safely.

5. surface volume 1886
In ArcGIS Pro, the "Surface Volume" tool can be used
to calculate the volume of material that has been
added to or removed from a surface over a specified
period of time. This can be useful for a variety of
applications, including measuring the volume of
earthmoving projects, calculating the volume of
sediment deposited in a river or stream, and
estimating the volume of material that has been
removed from or added to a site due to erosion or
other processes.
To use the "Surface Volume" tool in ArcGIS Pro, you
will need to have the 3D Analyst extension installed.
With the 3D Analyst extension, you can access the
"Surface Volume" tool by going to the "3D Analyst"
tab and clicking on the "Surface Volume" button.
To use the tool, you will need to provide two input
surfaces: a "Before" surface representing the initial
state of the surface, and an "After" surface
representing the final state of the surface. The tool
will then calculate the volume of material that has
been added or removed between the two surfaces.
The results of the calculation can be displayed as a
3D surface or as a table of values.
Surface volume 1866
Surface volume 2022

6. Cutfill:
In ArcGIS Pro, the "Cut Fill" tool is used to calculate the
volume of material that has been added to or removed
from a surface. This can be useful for a variety of
applications, including estimating the amount of material
required for an earthmoving project, calculating the
volume of sediment deposited in a river or stream, and
estimating the volume of material that has been
removed from or added to a site due to erosion or other
processes.
To use the "Cut Fill" tool in ArcGIS Pro, you will need to
have the 3D Analyst extension installed. With the 3D
Analyst extension, you can access the "Cut Fill" tool by
going to the "3D Analyst" tab and clicking on the "Cut
Fill" button.
To use the tool, you will need to provide two input surfaces: a "Before" surface representing the initial state of the
surface, and an "After" surface representing the final state of the surface. The tool will then calculate the volume of
material that has been added or removed between the two surfaces and display the results as a 3D surface or as a
table of values. The results can be used to visualize the changes in the surface and to estimate the amount of
material required for an earthmoving project.
eroded
volume
sedimented
volume
erosion
speed
sedimentation
speed
area affected
by
sedimentation
Area affected
by erosion
1301766989
m3
-7427727898
m3
9571816.096
m3
/year
-54615646.31
m3
/year
780010741.9
m²
659441258.1
m²